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EPA BLACK CARBON AND GLOBAL WARMING

HEARING

BEFORE THE

COMMITTEE ON OVERSIGHT

AND GOVERNMENT REFORM

HOUSE OF REPRESENTATIVES

ONE HUNDRED TENTH CONGRESS

FIRST SESSION

OCTOBER 18, 2007

Serial No. 110–86

Printed for the use of the Committee on Oversight and Government Reform

(

Available via the World Wide Web: http://www.gpoaccess.gov/congress/index.html

http://www.house.gov/reform

(II)

COMMITTEE ON OVERSIGHT AND GOVERNMENT REFORM

HENRY A. WAXMAN, California, Chairman

TOM LANTOS, California

EDOLPHUS TOWNS, New York

PAUL E. KANJORSKI, Pennsylvania

CAROLYN B. MALONEY, New York

ELIJAH E. CUMMINGS, Maryland

DENNIS J. KUCINICH, Ohio

DANNY K. DAVIS, Illinois

JOHN F. TIERNEY, Massachusetts

WM. LACY CLAY, Missouri

DIANE E. WATSON, California

STEPHEN F. LYNCH, Massachusetts

BRIAN HIGGINS, New York

JOHN A. YARMUTH, Kentucky

BRUCE L. BRALEY, Iowa

ELEANOR HOLMES NORTON, District of

Columbia

BETTY MCCOLLUM, Minnesota

JIM COOPER, Tennessee

CHRIS VAN HOLLEN, Maryland

PAUL W. HODES, New Hampshire

CHRISTOPHER S. MURPHY, Connecticut

JOHN P. SARBANES, Maryland

PETER WELCH, Vermont

TOM DAVIS, Virginia

DAN BURTON, Indiana

CHRISTOPHER SHAYS, Connecticut

JOHN M. MCHUGH, New York

JOHN L. MICA, Florida

MARK E. SOUDER, Indiana

TODD RUSSELL PLATTS, Pennsylvania

CHRIS CANNON, Utah

JOHN J. DUNCAN, JR., Tennessee

MICHAEL R. TURNER, Ohio

DARRELL E. ISSA, California

KENNY MARCHANT, Texas

LYNN A. WESTMORELAND, Georgia

PATRICK T. MCHENRY, North Carolina

VIRGINIA FOXX, North Carolina

BRIAN P. BILBRAY, California

BILL SALI, Idaho

JIM JORDAN, Ohio

PHIL SCHILIRO, Chief of Staff

PHIL BARNETT, Staff Director

EARLEY GREEN, Chief Clerk

DAVID MARIN, Minority Staff Director

(III)

C O N T E N T S

Page

Hearing held on October 18, 2007 .......................................................................... 1

Statement of:

Jacobson, Mark Z., professor of civil and environmental engineering, Atmosphere/Energy Program, Stanford University; Tami C. Bond, assistant professor of civil engineering, University of Illinois at UrbanaChampaign; V. Ramanathan, professor of climate and atmospheric

sciences, Scripps Institute of Oceanography, University of San Diego;

Charles Zender, associate professor of Earth system science, University

of California at Irvine; and Joel Schwartz, professor of environmental

epidemiology, Harvard University ............................................................... 12

Bond, Tami C. ............................................................................................ 30

Jacobson, Mark Z. ..................................................................................... 12

Ramanathan, V. ......................................................................................... 49

Schwartz, Joel ............................................................................................ 78

Zender, Charles ......................................................................................... 68

Letters, statements, etc., submitted for the record by:

Bond, Tami C., assistant professor of civil engineering, University of

Illinois at Urbana-Champaign, prepared statement of .............................. 32

Davis, Hon. Tom, a Representative in Congress from the State of Virginia, prepared statement of ........................................................................ 9

Jacobson, Mark Z., professor of civil and environmental engineering, Atmosphere/Energy Program, Stanford University, prepared statement

of ..................................................................................................................... 15

Ramanathan, V., professor of climate and atmospheric sciences, Scripps

Institute of Oceanography, University of San Diego, prepared statement of ........................................................................................................... 51

Schwartz, Joel, professor of environmental epidemiology, Harvard University, prepared statement of .......................................................................... 81

Watson, Hon. Diane E., a Representative in Congress from the State

of California, prepared statement of ........................................................... 110

Waxman, Chairman Henry A., a Representative in Congress from the

State of California, prepared statement of ................................................. 3

Zender, Charles, associate professor of Earth system science, University

of California at Irvine, prepared statement of ........................................... 70

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EPA BLACK CARBON AND GLOBAL WARMING

THURSDAY, OCTOBER 18, 2007

HOUSE OF REPRESENTATIVES,

COMMITTEE ON OVERSIGHT AND GOVERNMENT REFORM,

Washington, DC.

The committee met, pursuant to notice, at 10:06 a.m. in room

2154, Rayburn House Office Building, Hon. Henry A. Waxman

(chairman of the committee) presiding.

Present: Representatives Waxman, Maloney, Cummings,

Kucinich, Tierney, Norton, McCollum, Hodes, Davis of Virginia,

Shays, Mica, Duncan, Issa, and Bilbray.

Staff present: Phil Schiliro, chief of staff; Phil Barnett, staff director and chief counsel; Greg Dotson, chief environmental counsel;

Earley Green, chief clerk; Teresa Coufal, deputy clerk; Caren

Auchman and Ella Hoffman, press assistants; Leneal Scott, information systems manager; David Marin, minority staff director;

Kristina Husar, minority counsel; Larry Brady, minority senior investigator and policy advisor; Patrick Lyden, minority parliamentarian and member services coordinator; Brian McNicoll, minority

communications director; Benjamin Chance, minority clerk; and Ali

Ahmad, minority deputy press secretary.

Chairman WAXMAN. The meeting of the committee will please

come to order.

Today’s hearing will focus on the issue of black carbon and global

warming. Black carbon is commonly known as soot. It is emitted

from our diesel trucks, our trains, planes, ships, and even our fireplaces. Over the years, Congress and the Environmental Protection

Agency have focused on tiny particles like black carbon because it

cut short the lives of our seniors and sickened our children; however, black carbon is also important because of the ongoing role it

plays in the warming of the Earth.

Today we will hear that black carbon may be responsible for almost 20 percent of the warming the planet is currently experiencing. Experts will tell us that black carbon may be the second most

significant global warming pollutant after carbon dioxide; yet controlling black carbon has not been seriously examined at the Federal level as a way of possibly mitigating global warming.

At today’s hearing we will explore what may seem to be an overwhelmingly complex issue involving atmospheric chemistry, global

climate modeling, and literally millions of sources of air pollution.

It may seem complex, and indeed there are complexities and unanswered questions, but it is manageable. Here is what we know:

Global warming is happening and carbon dioxide is the principal

pollutant of concern. Other pollutants, like black carbon, also conVerDate 11-MAY-2000 11:41 Nov 12, 2008 Jkt 000000 PO 00000 Frm 00005 Fmt 6633 Sfmt 6633 C:\DOCS\45164.TXT KATIE PsN: KATIE
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tribute to the problem. Because black carbon doesn’t stay in the

Earth’s atmosphere as long as carbon dioxide, controlling it may

achieve major benefits in the short term.

We may need short-term benefits in order to prevent irreversible

impacts from occurring. Reducing particulate air pollution, like

black carbon, could also achieve major public health benefits.

This is not a theoretical issue. We can now see the impacts of

global warming with our own eyes. To illustrate this last point, I

have several slides of glaciers that I would like to put up on the

screen.

This first is of Carroll Glacier in Alaska. As you can see, this glacier has basically disappeared in the 97 years between when these

photographs were taken. As you can see it is a straight glacier untouched by any warming, complete ice, no deterioration. We will

soon see a photograph that shows a very different picture.

We also have photographs which we will exhibit in the near

term, and these photographs are of McCall Glacier, which has receded dramatically over the last 45 years, and then there is also

Toboggan Glacier that has vanished over the course of 90 years.

The glaciers of the world are receding. These receding glaciers

are one measure of the warming that we now know to be occurring,

but it isn’t the only one. What is happening in the Arctic is alarming.

We have a time-lapsed animation of Arctic sea ice. This animation shows the last 30 years of summer sea ice, based upon data

compiled by the National Snow and Ice Data Center. It begins in

1978 and runs through 2007. While Arctic sea ice has been consistently declining over the years, this past summer was truly stunning.

If you look on the right, you can see the area that has now been

lost, which has opened up perhaps sea lanes that we never expected, but problems that we should definitely be concerned about.

Global warming is happening, and the planet’s natural systems

are giving us every reason to pay attention to this problem.

Today we have a very distinguished panel and I thank you all

for being here and for paying attention to this problem. I am very

pleased that they have agreed to appear, and we look forward to

your testimony.

We want to bring in part of the debate on global warming that

has not been the focus of attention yet on the Hill, and we think

this hearing will give us the opportunity to do that.

[The prepared statement of Chairman Henry A. Waxman follows:]

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Chairman WAXMAN. Mr. Davis.

Mr. DAVIS OF VIRGINIA. Thank you, Mr. Chairman, and thank

you for holding today’s hearing to consider the relationship between black carbon emissions and climate change.

Climate change is a critically important issue, and as policymakers it is our job to consider all sensible options to reduce the

emission of climate-warming pollutants. My head is not in the sand

on this issue. I am not one who denies the reality of climate

change, and I am motivated to learn more about what we can do

to advance the debate and come up with some potential solutions.

Therefore, I think this hearing can serve as an example of how we

as a committee can work together to rationally investigate the facts

surrounding climate change, and at the same time seek agreement

on the best way forward.

While the United States and the world have focused attention on

reducing carbon dioxide emissions, it appears that not enough attention has been focused on controlling black carbon and its effects

on the climate.

According to the witnesses scheduled to testify, there is significant scientific evidence that black carbon is the second leading

cause of climate change after carbon dioxide. In layman’s terms,

black carbon is soot. It is emitted into the air during fossil fuel and

biofuel combustion and biomass burning. Developing nations like

China and India are the leading source of black carbon emissions,

while the United States is only responsible for about 6.1 percent.

Unlike some ways of controlling CO2 emissions, technology already is available to reduce emissions in black carbon. That technology has reduced by a factor of five the soot emissions in this

country since the 1950’s. We need to find ways to ensure the developing world has access to this technology.

One witness will tell us that reductions in black carbon emissions could buy us significant time to reduce CO2 emissions. That

would be a welcome respite to allow the world to develop consensus

solutions that don’t stall growth or give some nations competitive

advantages over others.

Because the developing world is the major source of black carbon

emissions, this hearing serves as a reminder that any future international treaties on climate change must include China and India.

Failure to do so would forfeit a prime opportunity to bring about

meaningful changes in behavior that both include quality of life

and reduce the immediate impact of climate change on the planet.

Moreover, as we look for ways to mitigate harmful greenhouse

gases, we must do so while acknowledging that energy is essential

to the economic activity that sustains and improves our quality of

life.

Renewable energy shows great promise, and biofuels have provided some relief from our dependence on traditional energy

sources that contribute to climate change. However, the only fuels

that have a realistic growth potential—solar, wind, biomass—only

make up about 3.5 percent of the Nation’s energy supply. Even

with healthy growth, these energy sources will not cure our dependence on coal and oil. Accordingly, policymakers must look to

technologies that decrease the externalities associated with the use

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of energy so that we can limit emissions that contribute to climate

change.

There is no question that we live in a challenging world and we

only have real-world options available to us to address the twin

challenges of climate change and energy independence.

This committee and this Congress should devote more time and

attention to exploring these options so that we can craft effective,

real-world solutions. Reducing black carbon emissions around the

world may be an overlooked, cost-effective solution that will provide enormous benefits.

Finally, I want to thank our distinguished panel who will be testifying today for their dedication to the science of climate change

and for taking the time to share their knowledge with us and their

expertise.

Thank you.

[The prepared statement of Hon. Tom Davis follows:]

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Chairman WAXMAN. Thank you.

We have a very distinguished panel.

Mr. Issa, did you want to say anything? If not, we will proceed

to the panel.

Mr. ISSA. That would be fine just to proceed.

Chairman WAXMAN. OK.

We have Dr. Mark Jacobson, who is the co-founder and director

of the Atmospheric Energy Program at Stanford University’s Department of Civil and Environmental Engineering, where he has

been a faculty member since 2004. His research is dedicated to addressing atmospheric problems such as climate change and urban

air pollution. Since 1994, he has published two textbooks and more

than 70 peer-reviewed journal articles on related topics. We are

pleased that you are here.

Dr. Tami Bond leads a research group at the University of Illinois at Urbana-Champaign focused on aerosols and the global environment. She is well known for her work identifying black carbon

emission sources. We are pleased that you are here.

Dr. V. Ramanathan has been researching climate and atmospheric science for more than 30 years. Among other positions, he

currently serves as a member of the World Clean Air Congress Advisory Board as co-chief scientist for the Atmospheric Brown Cloud

Project and is Chair to the National Academy of Science’s Committee on Strategic Advice on the U.S. Climate Change Science Program. He is a distinguished professor of atmospheric and climate

sciences at the Scripps Institute of Oceanography at the University

of California, San Diego.

Dr. Charles Zender is the director of the Earth System Modeling

Facility and leads the Climate Health, Aerosols, Radiation, and

Micro-Physics Group at the University of California, Irvine. His recent research focuses on the impact of aerosol deposits on snow and

ice in the Arctic, and he holds a Ph.D. in astrophysics, planetary,

and atmospheric science from the University of Colorado at Boulder. We are pleased you are here.

And Dr. Joel Schwartz is a professor of environmental epidemiology at the Harvard University School of Public Health. He has conducted research on the adverse health impacts of air pollution all

over the world, including studies in the United States, the European Union, Canada, Israel, and Turkey, among others. Dr.

Schwartz, it is good to see you, as well.

It is the practice of this committee to ask all witnesses that appear before us, because we are an investigative committee, to testify under oath. It seems a bit awkward with scientists, because

you are going to give us theories and ideas that may change. In

fact, you may change your minds as you look at some of these matters further. But we will keep with our practice and ask you to

please stand and raise your right hands.

[Witnesses sworn.]

Chairman WAXMAN. The record will reflect that each of the witnesses answered in the affirmative.

Dr. Jacobson, let’s hear from you first.

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STATEMENTS OF MARK Z. JACOBSON, PROFESSOR OF CIVIL

AND ENVIRONMENTAL ENGINEERING, ATMOSPHERE/ENERGY PROGRAM, STANFORD UNIVERSITY; TAMI C. BOND, ASSISTANT PROFESSOR OF CIVIL ENGINEERING, UNIVERSITY

OF ILLINOIS AT URBANA-CHAMPAIGN; V. RAMANATHAN,

PROFESSOR OF CLIMATE AND ATMOSPHERIC SCIENCES,

SCRIPPS INSTITUTE OF OCEANOGRAPHY, UNIVERSITY OF

SAN DIEGO; CHARLES ZENDER, ASSOCIATE PROFESSOR OF

EARTH SYSTEM SCIENCE, UNIVERSITY OF CALIFORNIA AT

IRVINE; AND JOEL SCHWARTZ, PROFESSOR OF ENVIRONMENTAL EPIDEMIOLOGY, HARVARD UNIVERSITY

STATEMENT OF MARK Z. JACOBSON

Mr. JACOBSON. Thank you, Chairman Waxman, Ranking Member

Davis, and the committee for inviting me to testify today. I will

speak on the role of black carbon in global climate change and

methods of reducing black carbon emissions.

Fossil fuel and biofuel burning soot particles containing black

carbon have a strong probability of being the second leading cause

of global warming after carbon dioxide and ahead of methane. Because of the short lifetime of soot relative to greenhouse gases, control of soot, particularly from fossil fuels, is very likely to be the

fastest method of slowing global warming. Because soot particles

are generally small, and small aerosol particles are the leading

cause of air pollution mortality, controlling soot emissions will not

only slow global warming but also improve human health.

The U.S. soot contributions to global warming may exceed each

of its methane and its nitrous oxide contributions to global warming. Despite soot regulations to date based on health grounds, the

United States has significant room to reduce soot emissions further, thereby reducing health and climate problems further.

Soot is an aerosol particle emitted during fossil fuel, biofuel, and

biomass combustion. Soot particles contain black carbon, organic

carbon, and smaller amounts of sulfur and other chemicals. Soot

particles warm the air by converting sunlight into infrared or heat

radiation and emitting the heat radiation to the air around them.

This differs from greenhouse gases, which heat the air by absorbing the Earth’s infrared radiation but not sunlight.

When soot particles age in the atmosphere, they become coated

by other chemicals, increasing their size and their ability to heat

the air, but also their ability to form clouds. Soot particles that end

up on snow or sea ice surfaces also darken those surfaces, contributing to their warming and melting.

The figure now on the screen shows the relative contributions of

greenhouse gases, soot, the urban heat island effect, and cooling

particles to global warming, as determined by recent detailed computer model simulations. About half of actual global warming today

is being marked by cooling particles which contain sulfate, nitrate,

ammonia, certain organic carbon, and water primarily. Thus, as

cooling particles are removed by the cleanup of air pollution, much

global warming will be unmasked; nevertheless, the removal of

such particles is still desirable for improving human health.

The figure also shows that fossil fuel plus biofuel soot may contribute to about 16 percent of gross global warming, which is the

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warming before cooling is subtracted out, but its control and isolation could reduce 40 percent of net global warming.

Soot particles also differ from greenhouse gases in that soot particles have relatively short lifetimes of around 1 to 4 weeks. This

compares with 30 to 43 years for carbon dioxide and 8 to 12 years

for methane. The lifetime of a chemical is the time required for its

concentration in the air to decay to about 37 percent its original

value.

Because of soot’s short lifetime and strong climate impacts, reduction in its emissions can result in rapid climate benefits. This

is illustrated by the figure now on the screen, which shows that

controlling soot could reduce temperatures faster than controlling

carbon dioxide for up to 10 years, but controlling carbon dioxide

has a larger overall climate benefit over 100 years.

Whereas the United States emits about 21 percent of global anthropogenic carbon dioxide, it emits about a little over 6 percent of

global fossil fuel plus biofuel soot. Nevertheless, the warming due

to U.S. soot appears to exceed the warming due to U.S. methane

and nitrous oxide.

Proposed methods of controlling fossil fuel soot have included improving engines, changing fuels, adding particle traps, and changing vehicle types. Recent emission regulations in the United States

have begun to address reducing particle emissions, but more needs

to be done.

It is thought that because diesel vehicles contain better gas mileage than gasoline vehicles, using more diesel will slow global

warming; however, this concept ignores the larger emissions of fossil fuel soot from diesel and the resulting climate effects. Further,

the addition of a particle trap to diesel vehicles, while decreasing

particles significantly, increases carbon dioxide, and the ratio of

NO2 to NO in exhaust, thereby increasing ozone in most of the

United States.

Improvements in neither gasoline nor diesel vehicles can contribute significantly to reducing carbon dioxide emissions by 80 percent, the level needed to stabilize atmospheric carbon dioxide, while

accounting for future economic growth. A more certain method is

to convert from fossil fuel to electric, plug-in hybrid, or hydrogen

fuel cell vehicles, where the electricity or hydrogen is produced by

a renewable source such as wind, solar, geothermal, hydroelectric

wave, or tidal power. Such a conversion would reduce global warming and improve human health simultaneously.

The figure on the screen shows results for the first wind mapping

study of North America at 80 meters above the ground. This is all

from data. The Great Plains has long been known as the Saudi

Arabia of wind, but the figure identifies other ares, particularly

coastal, of intense winds that were previously unknown. The data

indicate that the United States has twice as much wind energy

than total energy consumed from all sources, and ten times as

much wind energy as electricity consumed in locations where wind

is economical.

The United States could replace all its on-road vehicles with battery electric vehicles powered by 71,000 to 122,000 5-megawatt

wind turbines, which is less than the 300,000 airplanes produced

during World War II by the United States.

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The land area needed for such wind turbines is 0.5 percent of the

United States, much less than the 15 percent of the United States

that has fast wind. The wind area required is also 1/30th of that

required for corn ethanol and 1/20th of that required for cellulosic

ethanol to replace the same vehicles. The land area required for

solar energy is also very low.

In sum, an effective method of reducing the combined effects of

carbon dioxide and soot on climate and health is to convert as

many combustion devices as possible to those powered by renewable energy.

Thank you again for considering my testimony.

[The prepared statement of Mr. Jacobson follows:]

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Chairman WAXMAN. Thank you. We appreciate that testimony.

Dr. Bond, we would like to hear from you.

STATEMENT OF TAMI C. BOND

Ms. BOND. Chairman Waxman, Ranking Member Davis, and

members of the committee, I have spent the last 12 years modeling

and measuring sources of black carbon, and I am pleased to share

my expertise about the role of black carbon in climate change.

I commend your committee for continuing this discussion at a national level, and I am honored to participate. Thank you very much

for your invitation.

I will speak to you on sources of black carbon, its role in the climate system, and the potential for mitigation. These are the major

points of my presentation, which are supported further in my written testimony: First, the major sources of black carbon are known.

Second, historically clean alternatives reduce black carbon emissions. This transition occurs naturally during economic development, but it can be accelerated.

Third, black carbon and other products of incomplete combustion

should be considered together with greenhouse gases.

Fourth, mitigation options that address black carbon, particularly in developed countries, are not always cost effective compared

to greenhouse gases when climate benefits alone are considered.

Fifth, some options can economically reduce warming. These

offer major co-benefits in terms of human health and local environmental protection.

The first slide there is showing that black carbon emissions in

2000 came from four categories: diesel engines for transportation or

industrial use; solid fuels, such as wood and coal, for cooking and

heating; open forest and savannah burning, both natural and for

land clearing; and solid fuel use in industrial combustion.

The comparative magnitude of each contribution will change as

these estimates improve, but the major sources will neither vanish

nor grow to dominate the whole picture.

Fuel use in the United States has grown phenomenally since

World War II, but black carbon emissions have decreased due to

cleaner technology and fuels. Estimates of the North American

emission trend are broadly consistent with the Arctic record.

History suggests a consistent trajectory during a nation’s economic development. Initially, emissions come from solid fuels for

heating and cooking. These fade as incomes increase and clean

household energy is introduced.

Next, emissions from the industrial sector increase and are reduced by regulation. In the meantime, internal combustion engines

for transportation and other mobile power proliferate and eventually dominate.

It is rarely possible to reduce greenhouse gases alone, aerosols

alone, or black carbon alone. Evaluating all emissions from a single

source is more comprehensive and more accurate than looking at

the effects of individual chemical species such as carbon dioxide

only.

No current efforts on climate mitigation are evaluated in this

way; however, rapid changes such as those occurring in the Arctic

suggest that no opportunity should be missed.

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Particles from diesel engines and cook stoves are strongly light

absorbing and therefore warming, despite the presence of non-absorbing cooling particles from these sources. Particles from open

biomass burning, however, are on the border between cooling and

warming.

This figure shows a very preliminary evaluation of cost-effectiveness in terms of CO2 equivalent reductions. Here I discuss only

methods of eliminating existing black carbon emissions.

Mitigation options for solid fuel combustion include improving

wood cook stoves and promoting cleaner fuels, including distillate

fossil fuels. This would also reduce exposure to indoor smoke, a

major health hazard.

Reducing vehicle emissions is possible through accelerated retirement, retrofits, and targeting of high emitters.

The figure I show supports some optimism, because some costs

are close to worthwhile, even from a climate protection perspective.

Some reductions appear affordable, while some appear costly; however, consideration of immediate benefits, health and environmental protection, and Arctic snow forcing will decrease the costs,

as well. However, caution is also necessary.

First, many of the least-expensive mitigation actions can be

found in developing countries. Industrialized countries have already enacted many of the least-expensive aerosol reductions, and

the remaining black carbon is expensive to mitigate. Thus, acknowledging the role of black carbon in the climate system is unlikely to detract developed countries from reducing greenhouse

gases.

Second, reductions may be challenging, despite strong justification for climate protection. The two measures that appear most

promising—reducing diesel emissions and improving cooking

fuels—involve millions of small sources and operators, whose ability to afford the relatively low-cost investments is limited.

In conclusion, black carbon reductions can contribute to climate

protection, and exploration of this possibility should proceed rapidly, although cautiously. Reducing emissions can eliminate warming quickly, and in some cases economically. These measures also

result in major health and environmental benefits; however, they

are not always cost effective for climate purposes, alone, especially

in industrialized countries, and they reduce warming only in the

short term.

Thank you.

[The prepared statement of Ms. Bond follows:]

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Chairman WAXMAN. Thank you very much, Dr. Bond.

Dr. Ramanathan.

STATEMENT OF V. RAMANATHAN

Mr. RAMANATHAN. Honorable chairman and members of the committee, I am really honored to be here. I am going to talk about

more the global and regional effects of these black carbon particles.

They basically start off as soot as an urban or rural haze, and

then fast atmospheric transport spreads this haze far and wide in

a matter of a week over an entire subcontinent or an ocean basin.

My basic work is to use satellite measurements to track these

plumes and then launch aircraft to make detailed measurements of

their effects on climate.

In atmosphere, black carbon is mixed with other particles such

as sulfates, nitrates, and together the mix of manmade particles

are sometimes referred to as atmospheric brown clouds, or ABCs.

First, touching on the global warming issue, BC is one of the

strongest absorbers as far as particles are concerned of solar radiation in the atmosphere. My own estimates of BC heating from observations is that the current solar warming effect of BC is maybe

as much as 60 percent of that current CO2 greenhouse warming effect.

I want to point out that the estimates of the BC warming effect

are uncertain by a factor of three or more, as well as our understanding of the emissions.

Now, digressing to the whole mix of particles, I want to comment

on the global water budget. These brown clouds lead to large reductions in the amount of sunlight in the surface, and we call it dimming, and the corresponding increase in the solar heating. They

both are two sides of the same coin. Together, the ABC dimming

leads to a weaker hydrological cycle and drying of the planet,

which connects ABCs, or atmospheric brown clouds, directly to

availability of fresh water.

Moving on to the regional climate impacts, the regional effects of

brown clouds are estimated to be particularly large over Asia, Africa, and the Arctic. Since the dimming and atmospheric heating are

non-uniform in space and time, modern studies have linked the

black carbon effects on climate to the Saharan drought, the decrease in monsoon rainfall over India, and drying of modern China.

These are all recent model studies.

A more recent study by my group employing unmanned aerial vehicles [UAVs], shows from direct observations that black carbon enhances atmospheric solar heating by about 50 percent. This heating

may have contributed as much as greenhouse warming to the glacier retreat, which is a major, major issue for the Asian region.

I want to comment next to last on the black carbon reductions

and its effect on global warming. I basically consider this not as a

mitigation in complete, more as buying time, because the BC

warming effect may offer an opportunity to reduce the projected

warming trends in the short term.

The lifetime of BC is about a few weeks, so its effect would manifest almost immediately. The reduction of BC emissions is also important to public health, and I defer to my colleague, Dr. Schwartz,

for that.

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Let me proceed to understand, because of the uncertainty, by a

careful and well-documented, scientific study of the impact of black

carbon reduction. Toward this goal we have teamed up with a team

of NGO’s and public health experts and proposed a project in the

Periyar PURA region in India where we are going to adopt a large

rural area with 20,000 population and provide alternate cooking

and biogas plans and measure the impact of this on the atmosphere.

Last, I want to comment that the black carbon reduction is not

proposed as an alternative to CO2 reduction; at best, it is a shortterm measure to probably buy a decade or two, time for implementing CO2 emission reduction strategies.

The problem is highly uncertain, so I wanted to summarize with

what is it we have reasonable consensus on. First, the lifetime of

black carbon is about a few days to a few weeks is generally agreed

upon, and globally black carbon has a net warming effect on the

climate system, that is also generally agreed. However, the magnitude of the current warming effect is subject to a large uncertainty ranging from 15 percent to as much as 60 percent of the

warming effect of CO2.

Next also there is a consensus BC adds solar heating to the atmosphere but causes dimming of the surface.

The fifth point—again, reasonable consensus—is atmospheric

brown clouds’—this is ABCs—own particles lead to dimming of the

surface, and the global average effect of this is to decrease rainfall.

And the last point, which will be addressed by my colleague—we

have reasonable consensus on that—deposition of BC on sea ice

and snow darken the surface and leads to more solar absorption

and melting of sea ice and snow.

Prior confirmation is the regional effects of BC on shifts in the

rainfall patterns and the retreat of the Himalayan glaciers. These

need additional studies.

Thank you, Mr. Chairman.

[The prepared statement of Mr. Ramanathan follows:]

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Chairman WAXMAN. Thank you very much for your testimony.

Dr. Zender.

STATEMENT OF CHARLES ZENDER

Mr. ZENDER. Thank you Chairman Waxman, Mr. Davis, and

members and staff of the committee for hearing my testimony regarding the effects of black carbon on Arctic climate.

The Arctic is warming about twice as rapidly as the rest of

Earth. Although long-lived, manmade greenhouse gases are the

dominant cause of Earth’s recent warming, short-lived black carbon

particles explain a significant fraction of the observed Arctic warming.

My colleagues have described what BC is, where it comes from,

and how effectively BC reductions could slow near-term global

warming. The four points most relevant to black carbon in the Arctic are: First, that most Arctic black carbon comes from fossil fuel

combustion, not from open fires; second, black carbon appears to

warm the Arctic more than any other agent except CO2; third, Arctic climate is very sensitive to the surface warming of the type that

black carbon causes; fourth, reducing Arctic black carbon now will

cool the planet more than will a delayed reduction.

We know that economic and technological factors affect Arctic

black carbon concentrations. From 1880 to 1950, industrial emissions increased black carbon concentrations in Greenland’s snow

sevenfold relative to pre-industrial levels. Black carbon concentrations in Greenland have been lower since about 1950, likely due to

North American shifts in combustion fuels and technology, combined with wildfire suppression.

Black carbon decreased in some Arctic regions from the late

1980’s and early 1990’s during the decline of industrial activity in

the former Soviet Union. Late 20th century increases in Greenland

black carbon may be linked to increased coal combustion in the

rapidly expanding Asian economies.

There are three reasons why black carbon warms the Arctic more

than any agent except CO2. First, black carbon absorbs sunlight

and warms the Arctic atmosphere by approximately the same

amount as human injected CO2. This happens in spring and summer when snow and ice are most vulnerable to melting.

Second, black carbon also warms the Arctic, including in winter,

by thickening low-level clouds that then trap more of Earth’s emitted heat.

Finally, black carbon warms the Arctic after it lands on the surface. Uniquely, surface black carbon is an impurity that darkens

the otherwise bright Arctic snow and ice, causing them to absorb

more sunlight. This dirty snow, seen in the picture, warms and

melts the Arctic’s surface very efficiently, because the heat is

trapped at the surface by the strong Arctic temperature inversions

and by the insulating properties of the snow, itself.

Over the course of the Arctic spring, black-carbon-contaminated

snow absorbs enough extra sunlight to melt earlier, weeks earlier

in some places, than clean snow.

Melting Arctic surfaces uncover the darker, underlying surfaces

such as tundra and ocean. These dark surfaces then absorb even

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more sunlight, triggering a powerful climate warming mechanism

known as the ice-albedo feedback.

In the pre-industrial climate, black carbon was less effective than

wind-blown dust at triggering ice-albedo warming, but, as shown in

this slide, manmade greenhouse gases have not only warmed the

Arctic; they have exacerbated its vulnerability to warming by other

pollutants such as black carbon.

The diagram shows that darkening of snow and ice by humaninjected black carbon has warmed the Arctic by about half a degree

centigrade since the pre-industrial era. Warm snow is darker than

cold snow, so the ability of a cleaner Arctic surface to cool the planet will diminish as the Arctic warms. Snow and ice retreat also

weaken black carbon’s leverage over Arctic climate; hence, the diagram shows that reducing the concentration of black carbon now

will cool the Arctic significantly more than a delayed reduction.

Nothing in climate is more aptly described as a tipping point

than the zero-degree centigrade boundary that separates frozen

from liquid water—the bright, reflective snow and ice from the

dark, heat-absorbing ocean. Arctic snow, glaciers, and sea ice are,

on average, about 1.5 degrees centigrade warmer than in the preindustrial era. This may not sound like a lot, but each above-freezing day causes more melt, which amplifies the strong Arctic warming effects.

Greenhouse gas and black-carbon-induced warming are inexorably pushing more of the Arctic, earlier in the year, toward its

zero-degree centigrade tipping point.

In summary, because of its short life time and strong effects, reducing Arctic black carbon concentrations sooner rather than later

is the most efficient way that we know of to retard Arctic warming.

Thank you for your attention.

[The prepared statement of Mr. Zender follows:]

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Chairman WAXMAN. Thank you very much, Dr. Zender.

Dr. Schwartz.

STATEMENT OF JOEL SCHWARTZ

Mr. SCHWARTZ. Thank you very much, Chairman Waxman, Mr.

Davis, members of the committee. I am pleased to be here to talk

to you about the health effects of black carbon, if I can get my

slides up.

Chairman WAXMAN. I want to congratulate all of you on the successful slides that you have had available to you in your presentation. It is very helpful to be able to follow the slides and actually

see them.

Mr. SCHWARTZ. I want to start off by showing you what we are

talking about. Particulate air pollution is, in fact, the only manmade object that is visible from space, and you can see it here over

Bangladesh and the Himalayas up in the north.

You have heard a lot about what those particles do when they

are up in the atmosphere in terms of absorbing heat, but I want

to point out that the highest concentration of those particles is

about at that altitude here where people breathe, and so I want to

talk about what we know about the health effects of breathing

those particles.

One of the things we know comes from the Harvard Six Cities

Study, and this has now been replicated in a bunch of other cohort

studies, and that is that breathing particles shortens people’s life

expectancy, and by non-trivial amounts. This is after controlling for

hypertension, smoking, individual risk factors. The life expectancy

in six U.S. cities versus the PM2.5 concentration—which is the

total concentration of all combustion particles, not just the black

ones—you can see more than a 2-year difference in life expectancy

between the most-polluted and the least-polluted of these U.S. cities.

Again, this has been seen in multiple studies.

What is most interesting is what we saw when we went back to

those cities and looked at another 10 years of followup in this cohort of individuals we had been studying. That was that, as air pollution levels declined in U.S. cities, the mortality rates—not life expectancy, but mortality rates on the Y axis—went down. And in the

cities such as Stubenville with the ‘‘S’’ where there was a large

drop in particle concentrations, there was a large change in mortality rates, whereas in Topeka with the ‘‘T’’ you can see a small drop

in particle concentrations and a small drop in mortality rates.

So not only do we see that particles shorten life; we see that controlling particles results in a reduction in the mortality rate relatively quickly. So just as we get the global warming effects quickly, we get the mortality benefits quickly.

Now, again, this is talking about all combustion particles. What

do we know about black carbon in particular? Not nearly as much,

because we have only recently started to look at different kinds of

combustion particles. But there was a study in the Netherlands

where they estimated black carbon concentrations outside the

homes of people based on models they fit using their monitoring

data, and they also found that long-term exposure to black carbon

was associated with a shortened life expectancy.

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But what was interesting is the effect of the size that they saw.

The amount of shortening was bigger per unit reduction in black

carbon than what we saw per unit reduction of all combustion particles, suggesting that these particles, which in Europe and North

America are predominately from diesel, are more toxic than average. Getting rid of them has more health benefits than average.

We did a study in eastern Massachusetts where we also put out

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in black carbon concentrations over space and time, and then we

got data on all the deaths in eastern Massachusetts, and we

geocoded everybody’s addresses. Looking at the people who died

out-of-hospital, we found that, at the 75th percentile of black carbon concentration, 2.3 percent more deaths per day occurred than

at the 25th percentile of black carbon concentrations.

Again, this is larger than what we see for all combustion particles when we look at these short-term effects. And in this study

everyone was their own control. We looked at the black carbon outside the address of the subject the day before they died versus a

week earlier when they didn’t die. On average, it was higher the

day before they died. That is what drove those results.

Since black carbon is expensive to measure but since it predominately comes from traffic, there have also been studies that have

looked at traffic as a surrogate marker for this exposure. So we

looked at all of the confirmed cases of heart attack in Worcester

County over a period of a couple of years based on a heart attack

registry they have, and we did a case control study with 5,000

cases and 10,000 controls. We found that, again, going from the

25th to the 75th percentile, traffic density within 100 meters of

your house, increased your risk of having a heart attack by 4 percent, and at the same time controlling for that, every kilometer

closer you lived to a major highway increased your risk of a heart

attack by another 5 percent.

We followed people who had been admitted to the hospital for

heart failure, which is a growing disease in the United States, and

looked at their survival rate. We again found that doubling the

traffic within 100 meters of the home increased their risk of dying

in the next 5 years by 5 percent, and doubling the distance to a

bus route cut the risk by 3 percent, so a significant contributor to

mortality risks.

Now, that is in the United States, but, as you heard, most of the

black carbon emissions are actually coming from developing countries, and what can we say about them?

First of all, heart disease is an increasing cause of death in

China and in India, and so increasing risks for those matter to

them, too.

Second, we did a randomized trial of people in Guatemala in the

highlands retrofitting a chimney stove into their homes where they

cooked without a chimney before and reducing their exposure to all

of this biomass soot. What we saw in adult women in those homes

was that doing that reduced their blood pressure by about 3.5 millimeters of mercury. That is half as much as you can get from giving

people drugs to treat hypertension.

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So, as heart disease is a growing cause of death in the developing

world, there are opportunities there for them to improve the health

of their subjects and reduce mortality substantially by doing things

to control black carbon.

I would like to end by saying that the conundrum with carbon

dioxide control is that everyone gets to benefit, even if you are the

only one who pays. So we all want the other guy to pay. But you

only get the benefit of the health effects of reduced exposure to

black carbon if you are the one who reduces the exposure, because

these things occur locally.

So China and India are the ones that are going to reap the

health benefits of controlling black carbon in the future, and I

think that has great prospects for helping us to convince them that

it is time to act now.

Thank you.

[The prepared statement of Mr. Schwartz follows:]

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Chairman WAXMAN. Thank you very much.

I am going to start off the questions.

In 2002 the National Snow and Ice Data Center in Boulder, CO,

reported that summertime melting in the Arctic was at a record

level. If the Arctic sea ice continued to shrink at the same rate,

they predicted that the Arctic could be ice-free in the summer of

2050.

In February of this year the Inter-Governmental Panel on Climate Change confirmed this view, projecting that it was possible

that the Arctic could be ice free in summertime by the latter part

of this century. Many around the world were shocked to think that

we could see such a turn of events as soon as 2050, but then the

summer of 2007 brought unexpected melting. Arctic sea ice plummeted to the lowest level ever recorded, shattering the previous

record by nearly 25 percent. According to the National Snow and

Ice Data Center, sea ice may have fallen by as much as 50 percent

from the 1950’s.

On October 1st the Center reported that the sea ice is in a downward spiral and may have passed the point of no return. As a years

go by, we are losing more and more ice in summer and growing

back less and less in winter.

The Center went on to say that the Arctic Ocean could be icefree in summer as soon as 2030. According to some scientists, we

may lose the Arctic sea ice even sooner than that.

Dr. Zender, you testified that the Arctic is warming about twice

as rapidly as the rest of the Earth. Can you tell us if we need to

be concerned about what is happening in the Arctic? And also how

important is black carbon in what is happening in the Arctic?

Mr. ZENDER. Well, certainly the recent trends in Arctic sea ice

extent are quite troubling. As you mentioned, the long-term trend

until the last 1 or 2 years was about 8 percent per decade. With

this year’s record retreat, there is 23 percent less sea ice in the arctic than there was in 2005, the year of the previous record low.

What is troubling about these trends is that they are in agreement with model predictions that predict a steady decline followed

by an abrupt tipping point, or complete disappearance of summertime Arctic sea ice.

The disappearance of summertime Arctic sea ice would be hard

to imagine. It would be difficult to imagine a plausible mechanism

to restore that sea ice in the future. Melting of Arctic ice surfaces

is what you might call a wet process. It can occur very quickly. Ice

can slide into the ocean very quickly, whereas restoration of such

ice, sea ice, and glaciers is a slow, dry process that takes an order

of magnitude longer to occur.

Conservative estimates which placed summertime ice-free Arctic

in about the year 2040 a few years ago have reevaluated their findings. Many scientists think that an ice-free Arctic could occur much

sooner, perhaps as quickly as 20 years.

I think the overall concern that is unique to the Arctic about

warming is that when ice on land—not sea ice, but ice on land—

melts, it contributes directly and immediately to sea level rise. Sea

level rise is, of course, something that affects everyone worldwide

who lives near the coast.

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Chairman WAXMAN. The ice, if it melts in the water, would not

contribute to the increasing ocean levels?

Mr. ZENDER. That is true; however, the ice that melts in the

water does have an effect on the ocean circulation. By melting the

sea ice, we then uncover the underlying ocean, which warms up.

One of the critical areas in the Arctic that we are worried about

is the temperature of the ocean near the Northern Hemisphere’s

greatest ice sheet, Greenland. Warming ice near Greenland could

reduce the buttressing that the sea ice shelves have, which maintain the land glaciers that drain Greenland ice. If those buttresses

disappear, then Greenland’s ice balance will quickly turn more negative.

Chairman WAXMAN. Let me ask Dr. Jacobson, you testified that

because of black carbon’s short lifetime in the atmosphere, a reduction in its emissions can result in rapid climate benefits. If we

want to forestall the warming we are seeing happen in the Arctic,

is reducing black carbon part of the solution? And would we be able

to achieve results as quickly by focusing solely on carbon dioxide?

Mr. JACOBSON. Yes, it is part of the solution. I think, as I mentioned in my testimony, the global contribution to global warming

by black carbon from fossil fuel and biofuel sources is about 16 percent or so, and on a global scale. So theoretically, if you reduce all

the black carbon worldwide from those sources, you could have a

fast impact on reducing maybe proportionately not quite that number in the Arctic.

In the United States’s case, U.S.’s contribution is about 6 percent, so there is less of an impact on average.

Of course, it depends on the effect of the Arctic countries that are

responsible for the warming from black carbon, and it is not easy

to tell, but the United States is a portion, and then there is Europe, and then there is Russia, and there is Southeast Asia and

other parts of Asia that are contributing.

But we have definitely got a beneficial impact by controlling in

the U.S. black carbon. It is not going to be a huge impact. You have

to control the CO2 simultaneously to ensure long-term stability of

the Arctic, but you can get an immediate feedback, so there is a

benefit.

Chairman WAXMAN. CO2 control is not going to be sufficient

alone?

Mr. JACOBSON. Definitely not in the short term, because, because

of the long lifetime of CO2, the warming that is occurring in the

atmosphere due to CO2, even if we eliminated all emissions today

of CO2, anthropogenic emissions, you are not going to see the feedback on the global climate system for many years to decades to

come. We will see a little bit incrementally, but if you control all

the CO2 emissions today compared to all the black carbon emissions—and there is a lot more CO2 emitted—it would take at least

10 years before CO2 effects outpace the black carbon effects on this

climate impact. So it is faster cooling if you control the black carbon compared to the CO2; however, you want to do both simultaneously.

Chairman WAXMAN. Yes. Dr. Bond, you worked to understand

the sources of black carbon. Can you tell us if we know which

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sources we need to control if we want to reduce the presence of

black carbon in the Arctic?

Ms. BOND. There have been studies done that suggest that about

a third of the black carbon is from the United States and Europe,

and about a third is from the developing world, especially in south

and east Asia, and about a third is from arboreal forests. Now,

these are still uncertain, but those give you the biggest contributors.

I believe that we know the sources in each of those regions. In

the developed countries, as I mentioned during my testimony, a lot

of it is from transportation, including both on-road and off-road mobile sources. Both the United States and Europe have taken action

to reduce emissions from these sources, which means that they will

be coming down in the near future, but it also means that there

is experience in regulating those kinds of sources and in being successful at bringing the emissions down.

There are also measures to reduce emissions from solid fuel combustion in developing countries and, as well, from industrial combustion.

Those are the two major industrial type of sources that can be

reduced. I don’t think that we have a clear understanding of how

to reduce black carbon from open biomass burning, especially remote forest burning. Some of those options have been looked at in

terms of cost and they turn out to be extremely expensive, so I

would say that the transportation and residential solid fuels would

be the place to look first.

Chairman WAXMAN. Thank you.

Mr. Davis.

Mr. DAVIS OF VIRGINIA. Thank you very much, Mr. Chairman. I

want to thank the panel.

Now, Europeans have really moved to diesel, haven’t they, which

is worse for black carbon; is that correct? And so they may be

ahead of us in some ways and kind of behind. Is there any thought

there of scrubbing this and moving to something else?

Mr. JACOBSON. The Europeans, about 40 to 50 percent of all the

passenger vehicles sold are diesel. They emit a lot more NOx. A diesel vehicle emits a lot more oxides of nitrogen, maybe ten times

more than a gasoline vehicle. Also, without a control device, a huge

amount more, a factor of 5 to 10 more particulate matter——

Mr. DAVIS OF VIRGINIA. You can see it in a diesel.

Mr. JACOBSON. Yes. And so a lot of the new cars now, they put

particle traps on a lot of the new cars, but even with the particle

trap, the particle trap decreases the mileage of the diesel by about

3 to 8 percent, so that means more CO2 emissions, so there is a

tradeoff. By reducing the particles, you increase the CO2 emissions

from the vehicles, but also you also change this ratio in the exhaust

of the NO2 to NO.

In the United States, what that does is NO2 is a precursor to

ozone in smog. In the United States that really produces smog

right out of tailpipe. In Europe, where it is a little higher latitude,

it is not so much. But in the United States we did a study looking

what the effect would be, and you increase on average ozone over

the United States by adding a trap to new diesel vehicles.

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Mr. DAVIS OF VIRGINIA. Let me ask, I don’t know who is best able

to answer this, but what happens to black carbon once it has

reached its life span? Does it just disappear? Does it settle on ice

and continue to trap heat? Does it settle but stop conducting heat?

What happens? What is the life span?

Mr. JACOBSON. Most of it is removed by precipitation and most

of it will go over the ocean. Now, the stuff that settles onto snow,

that will have a longer impact if it settles onto snow or sea ice because it sits there for a while until it gets buried or it sinks or is

covered up by more snow, but even that more snow will have some

black carbon. So most of it is removed to the oceans eventually, and

a lot of it will deposit to the surface, too, in rain or in just some

deposition to the surface. That stuff, because the surface is soil or

blacktop or whatever it is, it is not going to have much of an impact there except maybe if it goes over sand in the desert.

Mr. DAVIS OF VIRGINIA. Dr. Ramanathan, let me ask you what

percentage of the melting ice sheets in the arctic can you attribute

to the black carbon? Is it hard to put a percentage on it?

Mr. RAMANATHAN. I have not by myself estimated the Arctic

part. I think that is what Dr. Zender was talking about. But the

key thing is in the Arctic, as I think was the point, the transport

comes from all directions. Some comes from east Asia. We track

these. Some comes from North America and eastern Europe, so all

these sources are contributing to that.

The one issue I want to point out which has not come up is that

with the sea ice retreating, there are no talks about new ships

traveling through the open water, and ships are a major source for

black carbon. I am concerned that now there is going to be an additional source of black carbon directly depositing and facilitating

more ship traffic. That is an issue that has not come up yet and

we need to worry about that, too.

Mr. DAVIS OF VIRGINIA. Let me ask Dr. Bond what respective

roles should the developing and the under-developed nations play

in mitigating the emissions of black carbon? What I am trying to

say is, Was it a mistake not to include that in the Kyoto Protocol?

Ms. BOND. Was it a mistake? No. The Kyoto Protocol was a first

step. It was never meant to be the ultimate solution.

Mr. DAVIS OF VIRGINIA. The end all. Yes.

Ms. BOND. So I am not going to comment on what we should

have done in the Kyoto Protocol. What matters is what we can do

now and next. I don’t believe that we can reduce black carbon impacts on the global atmosphere without the cooperation of developing countries, but I think that all of this is consistent with the

Framework Convention on Climate Change, which refers to differentiated responsibilities between developed and developing countries.

Mr. DAVIS OF VIRGINIA. Sure.

Mr. RAMANATHAN. I think we have to remember that close to 80

percent of the black carbon emission comes from developing nations.

Mr. DAVIS OF VIRGINIA. Right.

Mr. RAMANATHAN. Asia, Africa, Latin America. Because of the

impact of the black carbon on the local and regional climate and

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the glacier retreat, my own experience with India and China is

there is tremendous interest in focusing on the air pollution issues.

Mr. DAVIS OF VIRGINIA. Yes. I have been to Shihon in China

where people have to wear masks over their faces. That is the

health issues that you addressed earlier, in addition to the global

warming. But the polar caps, how much of this stuff finds its way

up there? Obviously, you are talking about the steamships and

planes, but is there that much other stuff up there that is generating the black carbon at the polar caps?

Mr. RAMANATHAN. I will defer to others.

Mr. ZENDER. The concentrations of black carbon in the Arctic are

relatively low relative to the developing world where the sources

are. The problem in the Arctic is that this black carbon has essentially a double or even triple lifetime. Because the Arctic is so very

bright, as you know, the sunlight that it can absorb has two

chances to be absorbed by it: on its way down, and on its way back

up being reflected from the ice sheets. But then that third lifetime

that I mentioned is once it lands on the surface a very, very small

concentration of black carbon—we are talking parts per billion——

Mr. DAVIS OF VIRGINIA. It is just more potent there, basically? Is

that what you are saying?

Mr. ZENDER. It is just more potent. It is the most potent warming agent we know of in the Arctic.

Mr. DAVIS OF VIRGINIA. OK. So it may not be significant in terms

of its volume compared to other places, but it just has a more potent effect there?

Mr. ZENDER. That is right. The exposure to inhaled black carbon

is very low in the Arctic; it is the atmospheric and surface effects

and their consequences on climate that are of the most immediate

concern, I think.

Mr. DAVIS OF VIRGINIA. Now, the sources for black carbon for the

developed world are basically different from the developing world?

For example, in Africa you have wood-burning stoves, we are cutting down and burning trees, and it may be diesel in Europe. Is

that fair to say?

Ms. BOND. It is fair. It is a different mix. We still have fireplaces

here.

Mr. DAVIS OF VIRGINIA. Right.

Ms. BOND. So it is not completely different, but for the most part

this country and Europe has the benefit of access to clean household energy, but we have a lot of transport. We have a lot more

transport because we have more goods. So there is a different mix,

and if you——

Mr. DAVIS OF VIRGINIA. So if you fly a private plane somewhere,

you are creating more black carbon, basically?

Ms. BOND. That is true.

Mr. DAVIS OF VIRGINIA. As opposed to flying coach or first class

or something somewhere else, I mean, just to get into it. Yes.

If we make these technologies available to the developing world,

are they available now and just not economic? I mean, what is the

issue? I know in China we talked about Shihon. In Beijing we were

there and didn’t see the sky for 3 days, the smog was so bad. I

mean, you would think over there if you make these technologies

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available somebody would do something about it. What is the problem?

Mr. RAMANATHAN. I can comment on rural regions of India.

Mr. DAVIS OF VIRGINIA. OK. India is fine.

Mr. RAMANATHAN. Major source of biofuel. The government has

connections to gas, natural gas, for cooking, but they can’t afford

it, so it is in some parts technology and others just sheer affordability of it.

Mr. DAVIS OF VIRGINIA. When you said that you meant natural

gas or propane. Propane in the Third World is the preferable choice

if available.

Mr. RAMANATHAN. This is methane, not propane.

Mr. DAVIS OF VIRGINIA. Thank you, Mr. Chairman.

Chairman WAXMAN. Thank you, Mr. Davis.

Mr. Cummings.

Mr. CUMMINGS. Thank you very much, Mr. Chairman.

Each of the witnesses today have emphasized that there are opportunities for mitigating emissions of black carbon. It seems that

if we could reduce emissions of black carbon we could potentially

realize significant climate benefits.

Dr. Jacobson, what is your advice to us as we begin to explore

controls of black carbon emissions?

Mr. JACOBSON. Sir, there is the direct way of reducing emissions,

which is adding particle traps to vehicles. In the United States, it

is the off-road vehicles that are creating the most emissions, the

construction machines.

Mr. CUMMINGS. The adding particle traps, is that a very expensive venture?

Mr. JACOBSON. I don’t know the exact cost. The number I heard

per tractor was $3,000, maybe to $5,000 or $6,000 if it is a big tractor, but that was a few years ago. I don’t know. Tami might now.

Mr. SCHWARTZ. You know, for a bus or for a typical sized piece

of construction equipment it is a couple of thousand dollars to add

these things, but then they last for a long time. That is a capital

cost.

Mr. CUMMINGS. When you say cost, you mean perhaps the life of

the bus or the tractor?

Mr. SCHWARTZ. Yes. Or at least a good fraction of the life. The

thing is that the new rules the U.S. EPA put out and the new Euro

Five standards for diesel engines are only for new diesel engines.

There is no retrofit requirement. That is where the opportunity is.

There is an opportunity to retrofit it on existing engines, because

diesel engines often last for 30 years.

Mr. CUMMINGS. Yes.

Mr. SCHWARTZ. That has been done. In London they retrofitted

all 6,000 London buses with particle traps in 2 years. In Massachusetts they are going to retrofit all the municipal and school buses

in a 3-year period. There are retrofit kits commercially for sale, and

it is definitely a doable thing.

Mr. JACOBSON. But let me caution. That is an immediate step,

but there are these unintended consequences, like the lower mileage, and therefore the higher CO2 emissions resulting from those

traps, and also the change in the NO2 to NO ratio, which affects

the ozone. This is particularly important for these big vehicles, the

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trucks especially that are replaced with traps. There you get the

highest ratio of NO2 to NO, which would exacerbate the smog the

most.

But I think even a better maybe—I don’t know if it is a shortor long-term—solution is really if you want to control both the soot

and the CO2 simultaneously and the other air pollutants coming

from these vehicles, it is really to switch your vehicle types to electric, plug-in hybrids, hydrogen fuel cell vehicles, because these all

can eliminate simultaneously your CO2, your black carbon, your

ozone precursors, and the ozone and the particulates are the ones

that cause most of the health problems, particulates even more.

So you can really solve the whole problem by really focusing on

these different types of vehicles rather than trying to incrementally

improve just the emissions of the black carbon or reduce the black

carbon.

Mr. CUMMINGS. Dr. Schwartz, you look like you are trying to

jump out your seat. Did you want to say something?

Mr. SCHWARTZ. Well, I agree that in the long term that is the

way to go, but I need to point out that there are retrofit kits, particle traps and particle filters, that can be put on vehicles tomorrow, and that hydrogen fuel cell-powered or all-electric garbage

trucks aren’t going to be here for quite a while, and so there is an

opportunity to have a staged strategy where we do something for

the existing fleet with the commercially available technology that

can be implemented in a couple of years, while developing the new

vehicles that replace those vehicles when they come to the end of

their lifetime.

Mr. CUMMINGS. OK.

Dr. Ramanathan, you have studied emissions in Asia. What can

you tell us about the mitigation opportunities there?

Mr. RAMANATHAN. It is my personal view there are huge opportunities in terms of trying to mitigate the global warming potential.

When you talk about Arctic, all these discussions are germane, but

when you want to reduce the global warming, potential black

carbon——

Mr. CUMMINGS. Can you keep your voice up?

Mr. RAMANATHAN. When you want to reduce the global warming

potential of black carbon, your focus has to be on Asia and Africa

and Latin America, because that is where the main sources are.

Although not an economist, I would venture to speculate it would

be a lot cheaper to try to mitigate black carbon emission in Asia,

particularly India and China in the major focus. For example, the

biofuel emissions, cooking with wood and cow dung is at least 50

percent of the total emission of black carbon from south Asia. Replacing those cookers with solar cookers or biogas plans, the relative cost we have to estimate. That is what we are trying to do.

But I think that is where the huge potential is there, the emission

of black carbon, coal-fired appliance in China and biofuels in India

and Africa.

This is a major vulnerable region. I wish I brought substance

abuse. You will see huge plumes covering most of central Africa

from the savannah burning. That is where I see major opportunities.

Mr. CUMMINGS. Thank you.

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Chairman WAXMAN. Thank you, Mr. Cummings.

Mr. Bilbray.

Mr. BILBRAY. Thank you, Mr. Chairman.

Dr. Schwartz, I have been sort of out of the business, the air resources business, for a while, so if you can give me a crash refresher course, when you were talking about the morbidity related

to diesel emissions, referring specifically to the particulates, I

didn’t hear you discuss what we ran into at the Air Resources

Board in California, which was that the true toxic component was

the benzene, and that the particulate was tending to be the carrying agent. Is the benzene still considered the most toxic component

in the diesel emission?

Mr. SCHWARTZ. Well, there is actually more benzene in the exhaust from gasoline vehicles than from diesel vehicles, because aromatics tend to have too much octane, and you don’t want octane

in a diesel engine, unlike in a gasoline engine, and so you tend in

a refinery to segregate the aromatics more to the gasoline. But

there is certainly benzene in diesel exhaust, and if you are talking

about cancer, then that is where the action is for sure.

But these deaths that we are looking at are deaths from heart

disease, and that doesn’t seem to be related to the benzene. It

seems to be related to something about——

Mr. BILBRAY. So yours was specifically to cardiovascular?

Mr. SCHWARTZ. To cardiovascular mortality, and that really

seems to be the particles.

Now, that said, it may well be that it is something that is carried

by these particles other than benzene, like metals or some other

things.

Mr. BILBRAY. We found that. I mean, all the talking back in the

1970’s was about dioxins. We found that the benzene in the diesel

trucks was like a magnitude of 10 to 20 over the toxicity of certain

dioxins and whatever, and so all at once we were realizing that to

reduce health exposure we weren’t doing waste incineration. We

were sending around three trucks to recycle materials, and the

health impacts were a net negative rather than a net positive.

When you did your modeling for morbidity, did you consider

socio-economic numbers?

Mr. SCHWARTZ. Yes, we controlled for socio-economics.

Mr. BILBRAY. I mean, let’s face it, the whole difference in places

like Pittsburgh in 20 years going from a coal/steel industry to a

high-tech industry, you do have a major jump between socio-economic, and that——

Mr. SCHWARTZ. And when you are talking about exposure to traffic, you have to remember the people who live on heavily trafficked

streets tend to be poorer than the people who live in the nice

houses.

Mr. BILBRAY. And people who are poor tend to have certain exposures.

Mr. SCHWARTZ. Absolutely. So, for example, in our study we had

individual education for each of the people who died, and then we

had census block group measures of socio-economic status we also

controlled for.

Mr. BILBRAY. Yes. The scrubber issue when I was working with

Mexico on Mexico City and we worked with Athens reducing their

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emissions, they went through the scrubber originally, but the natural gas conversion seemed to be the much cleaner quantum leap

sort of between where Mr. Jacobson is and where you are with the

scrubber of being able to use natural gas as the major source but

only using diesel as the igniter. Is there an environmental problem

with shifting off actually from being your major source of fuel for

these mobile sources from diesel over to natural gas?

Mr. SCHWARTZ. To my knowledge there isn’t an environmental

problem. Running buses on natural gas produces considerably less

particles than running buses on diesel with a particle trap, so the

natural gas conversion certainly would make sense. It makes more

economic sense on fleets of vehicles that operate around the city

and then come back to a terminal every day, either buses or trucks

and things where they can fill up with the natural gas, than on the

long-haul trucks where it is not always easy to find a source of

fuel.

Mr. BILBRAY. Where infrastructure is there.

Mr. SCHWARTZ. Where the infrastructure is easy to put in. Exactly.

Mr. BILBRAY. I appreciate that.

Dr. Jacobson, the discussion of the transition in California, we

were looking at the zero emission generators. California, we went

to natural gas with our stationary sources because it was the only

way to pencil out a lot of this generation within our air basins. The

question is: the low-lying fruit is going to be—correct me if I am

wrong—has always been stationary sources are always the place

we can get the most bang for the buck. I mean, if there was any

place historically we have been able to reduce substantially emissions with much more cost-effectiveness, stationary sources have

been that, hasn’t it?

Mr. JACOBSON. Well, yes. Historically in California most of the

electricity is natural gas. We don’t have much coal. We have a lot

of hydroelectric.

Mr. BILBRAY. Let me correct you, sir. You burn coal in California

air basins, you go to prison.

Mr. JACOBSON. Right. Yes. There is very little coal.

Mr. BILBRAY. Our concept is clean coal is about as logical as safe

cigarettes.

Mr. JACOBSON. Right. But there is emissions from natural gas,

but in California there is room for more renewable energy, of

course. That may not be in the question, but we did mapping of

winds offshore locations where you get really strong winds, and you

can combine wind with hydroelectric, geothermal, and solar and

you can power the entire State just about with the available resources.

Mr. BILBRAY. I just want to warn you, we got that issue, and

transmission becomes a hot issue.

Mr. JACOBSON. That is the limiting factor, and that is actually

why you kind of need maybe a national grid.

Mr. BILBRAY. But I agree with you. I think the big thing that

California is going to have to confront is stop using natural gas as

your stationary source because it will probably be our transition

fuel between what you are talking about and what you are talking

about, and we are burning it at power plants rather than using it

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for our off-road, which is now the big challenge, as Mr. Waxman

knows, in California, cracking down on those off-road emissions.

Thank you very much, Mr. Chairman.

Chairman WAXMAN. Thank you, Mr. Bilbray.

Ms. McCollum.

Ms. MCCOLLUM. Thank you, Mr. Chair.

This is a very interesting discussion, and I want to thank Mr.

Waxman for having it.

Dr. Schwartz, I was feeling pretty good about turning off the air

conditioner, leaving the windows open on a main street in D.C.

where I hear a lot of trucks, and I know I have a lot of soot because

I have to clean here more than I have to clean in the city of St.

Paul, MN, so my trying to save burning fossil fuels running an air

conditioner might lead to my increased risk of a heart attack, so

thank you very much for not making me feel much better about my

decision.

Mr. SCHWARTZ. Unfortunately, turning on the air conditioner and

closing your windows cuts the particle concentrations coming into

your house from outside in half.

Ms. MCCOLLUM. And I point that out because this isn’t a one-fix

solution; this is going to take a lot of different scientists such as

yourself sitting around the table and a lot of different people willing to look at different ways and to change their lifestyle, and businesses in the way that they operate in order to really tackle this.

This is, like I said, a very interesting discussion, and I thank the

Chair for having it.

In Minnesota we decided to retrofit our school buses—we are

calling it Project Green Fleet—to do what we could to reduce the

amount of carbon. Has there been any studies done, for example,

if all the school districts were to retrofit, what kind of impact it

could have? Would that be a model that we could look at to maybe

figure out some targeted ways where we could start doing things

and also get the word out?

Mr. SCHWARTZ. I don’t know of any studies that have looked at

what the impact of just targeting school bus fleets are. I think that

it is such a small fraction of the diesel fuel use in a given city that

you are not going to see very much if you just go after the school

buses as opposed to the construction equipment and the heavy duty

trucks and all the other things, as well.

Ms. MCCOLLUM. But sometimes the way to address the problem

is to get people to realize that there is a problem and to start talking about it.

Mr. SCHWARTZ. That is absolutely true, and there have been retrofit programs, and EPA funds some retrofit programs to go after

school buses. One thing that we can do that is a double winner is

all the buses you see lined up on Independence Avenue idling for

3 hours while the people that they drove to the museum are inside,

if you just turn off the engines of buses when you are not actually

driving some place then you save the CO2 and the carbon and all

sorts of other stuff. So awareness would be useful.

Ms. MCCOLLUM. We have done that, as well, in Minnesota, to

turn the buses off.

Mr. SCHWARTZ. That is good.

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Ms. MCCOLLUM. The developing world discussion is very interesting. I have had a fortune of traveling both in Asia and in Africa.

It seems to me that we need to look at doing something similar to

what we did with ozone with the Montreal Protocol on this.

Dr. Ramanathan, you have done a fabulous amount of work on

this. Can you share with this committee—I also serve on State and

Foreign Operations Appropriations—what we can do in working

with partner countries to help them reduce their health effects and

carbon?

Mr. RAMANATHAN. Thank you very much for that question.

I first of all would preface it, there is one thing we have to be

aware of. This outdoor haze or this pollution contains partially

black carbon, other particles, sulfates, nitrates, etc. These are all

cooling particles. The black carbon is heating. When you add all of

them together, they have massed as much as 50 of the global

warming from greenhouse gases. What that means is that we have

to be careful when we reduce those particulates.

See, the EPA, not only in the United States, but the EPAs of the

world, they are focusing on air pollution. Traditionally when there

is air pollution, it is sulfates. For example, I see in American media

we complain about sulfate emissions from China. The problem is

if you cut the sulfates and leave the black carbon behind, we can

have at least a factor of two amplification in the warming what we

will see just from air pollution regulations, because you are taking

off the cooling particles.

So we have to make sure. I am not saying we should leave the

sulfates behind. They have other ecosystem destruction. But we

should make sure when we remove the sulfates we also remove the

black carbon. That is No. 1 point.

In fact, Dr. Schwartz and I were in a big intercontinental air pollution meeting in Australia. We tried to bring it up. We tried to

educate the air pollution community. Be careful. What you do has

implications for climate change.

The second point I want to make is that again I don’t want to

be misunderstood. We have to cut down sulfate emissions because

of acid rain and others, but please let’s take out the black carbon

at the same time because the sulfates, if any, is shielding the planet from the global warming.

The second is the black carbon emission. I was in a meeting last

week where the Prime Minister was there, the finance minister, as

well as Mr. Jeb Bush, former Governor of Florida. I was surprised

how receptive they were when I talked about what the black carbon, haze, is doing to the regional climate and glaciers. As you

know, China is now trying to reduce the emissions in Beijing just

before the Olympic, and some of us are thinking this is a fantastic

natural experiment to see downwind what happens.

For example, we published a study last year: 75 percent of the

black carbon over the west coast of the United States during

springtime comes from long-range transport from east Asia. So we

are trying to see do we see an impact on air pollution just for this

1-month period.

Although I have not moved in government circles, my assumption is that they would be very receptive to United States and European governments trying to approach India and China on this

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issue and see how collaborations and resource sharing would help

them bring down the black carbon emission.

Chairman WAXMAN. Dr. Bond, did you want to comment?

Ms. BOND. I did, if you would allow me to.

Chairman WAXMAN. Sure.

Ms. BOND. I would like to point out that there is already collaboration between governments. At the Sustainable Development

Meeting in Johannesburg, the United States and other countries

initiated the Partnership for Clean Indoor Air. Now, this was not

a climate or outdoor air protection committee; it was a group of organizations that now numbers about 150 NGO’s and government

organizations internationally, and they are working on the problem

of household energy and solid fuels. That is something that has already been started.

Now, the climate benefits have not really been brought into that

picture, but they are very receptive.

Chairman WAXMAN. Thank you, Ms. McCollum.

Mr. Shays.

Mr. SHAYS. Thank you. Mr. Chairman, really thank you so much

for holding this hearing. It is rare when we have all doctors coming

before us, so when I say ‘‘doctor’’ I will now have to use a name.

I would first like to ask Dr. Bond if you would turn to page 4.

I am trying to understand where liquified LNG plants—there is a

real effort to bring LNG into the United States, and it is somewhat

controversial, particularly on Long Island Sound, and I have taken

a position against it and others have, but I begin to wonder. We

are at the end of the pipeline. Am I just making a bad decision

here or not?

Liquified natural gas, just explain this middle chart to me, page

4. ‘‘Energy increases faster than BC due to advances in technology.’’

First you describe different types—biofuel, coal, oil, Middle East,

light, distilled, aviation fuel, natural gas.

Ms. BOND. OK. Let me understand what you are trying to——

Mr. SHAYS. First explain this chart to me.

Ms. BOND. That chart is the global consumption of energy by

fuel.

Mr. SHAYS. OK.

Ms. BOND. In history.

Mr. SHAYS. Now explain to me, in terms of black carbon, is

liquified natural gas a less sooty, more sooty, indifferent?

Ms. BOND. Much less.

Mr. SHAYS. Much less.

Ms. BOND. Certainly. And the point of that figure was that it is

both improved technology and cleaner fuels that have contributed

to black carbon. This slower increase in black carbon emissions, if

black carbon emissions went up as quickly as energy did over the

last 50 years, we would not be able to breathe.

Mr. SHAYS. OK. Let me ask you this. In my house I have gas

coming in. I now have a heating system that they don’t want it to

exhaust up through the chimney; they put it through the side of

the house. Could they do that with oil as well, or is it more likely

they can do it with gas?

Ms. BOND. Gas burns a lot cleaner than oil.

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Mr. SHAYS. Right.

Ms. BOND. Especially during the transient periods where the furnace is turning on and off.

Mr. SHAYS. Thank you very much.

Dr. Ramanathan, would you explain to me the charges on eight?

It looks like the United States is not that bad a player compared

to others in the charts, these charts up top here. I am on page 8.

Mr. RAMANATHAN. Yes.

Mr. SHAYS. Explain those charts to me, if you would.

Mr. RAMANATHAN. Right. This is basically using most recent satellite measurements which give information about particulates, and

look at the total loading of particulates in the atmosphere.

Mr. SHAYS. And red would be the worst case?

Mr. RAMANATHAN. Red is worse. By the time you have seen those

charts green to yellow, you would already see the haze in the sky

as brown clouds.

Mr. SHAYS. So is that the soot blowing off our coast?

Mr. RAMANATHAN. Thank you. What you see of the east coast,

this is just not only soot, it is all particulates—sulfates, nitrates.

That is why we call them brown cloud.

Mr. SHAYS. All particulates. But basically it is in the air blowing

from the United States?

Mr. RAMANATHAN. Right. And you see that stream is all the coal

plants in the east coast just going across the Atlantic.

Mr. SHAYS. OK. And then in China and in India we just see a

mass of red.

Mr. RAMANATHAN. Exactly.

Mr. SHAYS. And it is all coal?

Mr. RAMANATHAN. And also I direct your attention to Africa, the

savannah burning.

Mr. SHAYS. Yes. Now, this is not in defense of the administration, but it is wanting to understand something. They are doing a

lot of bilateral agreements with various countries. The United

States was told be part of Kyoto, in spite of the fact that China and

India were not. They were told, you know, just be part of the family. If you can’t meet it, at least you are part of the team.

But my understanding is the United States has done, in comparison to Europe, not as bad as people would think. That is kind of

a negative way to say it, but actually we keep making some improvement. Is Europe making a lot more improvement versus the

United States in global warming issues and particulates? Any of

you can answer that, if that is all right.

Mr. RAMANATHAN. I think as far as the particulates are concerned, Europe versus the United States, I have the expert here.

I would rather let Dr. Tami Bond respond to that.

Ms. BOND. Are you talking about all global warming emissions?

Mr. SHAYS. Yes. Let’s do that first.

Ms. BOND. I am not sure I have the background to answer that,

because I haven’t really looked at energy intensity in Europe or the

United States.

Mr. SHAYS. Dr. Jacobson.

Mr. JACOBSON. I will try. I think, in terms of air pollution, the

United States has really been in the forefront, especially California.

I mean, California is really the leader in the world.

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Mr. SHAYS. Mr. Waxman’s State?

Mr. JACOBSON. Yes.

Mr. SHAYS. OK.

Mr. JACOBSON. Yes, in terms of air pollution control.

Chairman WAXMAN. As opposed to any other California.

Mr. JACOBSON. I am not biased.

Mr. SCHWARTZ. If I could add to that, if you look at the particle

concentrations in urban areas, they are lower in the United States

than they are in Europe. Part of that is because of their emphasis

on diesel engines, in fact, but not entirely. We have stricter standards on particle emissions in the United States than Europe.

Mr. SHAYS. Can I ask one last question, Mr. Chairman?

Chairman WAXMAN. Sure.

Mr. SHAYS. I live in an urban area. We have Indonesian ships

that come out way off coast. They transport the coal on the barge

and bring it in to a facility three-quarters of a mile from my house,

maybe a mile from my house. Should I prefer that they burn—I

think I know the answer—the so-called less-sulfur coal, or liquified

natural gas?

Mr. SCHWARTZ. You are going to get less CO2 emission per unit

of electricity generated and less particulate and sulfate emissions

per unit of electricity generated burning liquified natural gas than

burning coal, even low-sulfur coal.

Mr. SHAYS. Thank you.

Mr. JACOBSON. Can I comment on that? In Long Island there was

a proposed wind farm offshore, and that would obviously be better

than the other two.

Mr. SHAYS. Absolutely. Absolutely, but are they mutually exclusive? That is the question we have to ask.

Mr. JACOBSON. Yes.

Mr. SHAYS. Yes. Thank you very much. Thank you again, Mr.

Chairman.

Chairman WAXMAN. Thank you, Mr. Shays.

Mr. Hodes.

Mr. HODES. Thank you, Mr. Chairman. Thank you for having

this very important panel. I want to thank the panel for being here

today.

I want to focus first on black carbon international agreements.

There has been some mention here, but as I understand it black

carbon is not explicitly covered by international environmental

agreements. Now, black carbon doesn’t deplete the ozone layer, so

it isn’t covered by the Montreal Protocol. And black carbon isn’t

technically a greenhouse gas, so it is not covered by the United Nations Framework Convention on Climate Change. And the Kyoto

Protocol requires the developed world to reduce its emissions of certain greenhouse gases, but the protocol doesn’t include black carbon.

Given the depth of the problem which you have now graphically

outlined for us, as we engage in new negotiations aiming toward

the possibility of future international agreements that will succeed

the Kyoto Protocol, should we be seeking to include black carbon

in the agreement or agreements that hopefully we will participate

in? I can start with Dr. Jacobson, and then anybody else on the

panel. I would be interested in hearing your thoughts.

106

Mr. JACOBSON. I definitely think we should. Even though the

United States’ portion of the black carbon emissions is on the order

of 6 percent—not the largest—it is a good example to set for the

rest of the world. I strongly feel we should include it, because we

know it is a warming agent, and, as you mentioned, it is not being

controlled internationally, so it will have dual benefits of health

and climate, and I think it should be controlled.

Mr. HODES. Dr. Bond.

Ms. BOND. First of all, I agree with Dr. Jacobson, not just because we want to control all the warming agents, but I think we

really want to look at what we are doing when we undertake specific actions. And, as Dr. Jacobson has shown, you can decrease

carbon dioxide and increase warming if you don’t consider the

black carbon. So I think we should at least be comprehensive.

Second, I don’t agree that black carbon is not in the Framework

Convention. I would say it is not part of the objective, which refers

to stabilization of greenhouse gases. We don’t really want to stabilize black carbon anyway. However, the Framework Convention

does say that we should be comprehensive and that we should consider all sources, and sources include aerosols in their definition.

So I don’t think that what we are talking about is inconsistent, and

I do think that future agreements could be conducted under that

convention.

Mr. HODES. Could I just clarify for one moment? I appreciate the

clarification, but it sounds like we need to be more specific about

including black carbon as one of those sources which is of concern

and not leave it perhaps to the generalized framework that you referred to. Do you agree?

Ms. BOND. I would agree with that. At the time the Framework

Convention was written, this issue was not anywhere on the radar

screen.

Mr. HODES. Great. Thank you.

Mr. RAMANATHAN. I participated in the Intergovernmental Panel

on Climate Change. In addition, I run a United Nations environmental program called Atmospheric Brown Clouds focused on Asia.

We have all the nations participating in this research, and I can

give you a flavor of what Asians think about. We have Chinese. We

have Indians. We have Koreans. We have Japanese.

I think my feeling is pushing the black carbon issue at the same

level as the carbon dioxide in the international agreements may be

premature for this one small reason: the first definitive study of

the CO2 effects on climate was published 40 years ago. It took us

hundreds if not thousands of studies before we came to the state

where there was some general consensus. I don’t have to remind

you scientists rarely agree on anything. When you get five of us together in a room, you get conflicting opinions.

Compared to that, the black carbon issue is in its infancy. For

example, the study you heard by Professor Zender, my own study,

and Jacobson’s study, they are all less than 10 years old, and

science is confirmed by repeatability, many trying to repeat our results.

There is still a wide uncertainty, so when we take the black carbon issue to the table the ones who are opposed to that could take

the lowest estimate, which say it is not that important.

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It has not been properly vetted through the IPCC process. My

feeling is there could be more success than this by bilateral working within United States, Europe, India, and China, and try to

make progress on that because Dr. Schwartz’ research shows us

there are health problems and my research shows it has regional

problems, things like glacier melting and rainfall. So I think it may

be easier to push it on the regional impacts issue than on the global issue.

Mr. HODES. I appreciate the difficulty of reaching agreement on

those issues. It sounds a lot like working in Congress. We often disagree.

It sounds like you are addressing really the strategic implications

of how we deal with the issue, but is it fair to say that, at least

in your mind and that of the other panelists, there is no disagreement about the importance of dealing with black carbon?

Mr. RAMANATHAN. Yes, I agree with you. I agree with the opinions which were raised here. I am more thinking about the scientific uncertainty being larger so it poses strategic difficulties.

Mr. HODES. Thank you. I appreciate that.

Mr. Chairman, may I just give the other panelists a brief opportunity to finish the question?

Dr. Zender.

Mr. ZENDER. Thank you for the opportunity.

I agree with the panelists who summarized some of the conditions that led to the Framework Convention being oriented toward

the mitigation of greenhouse gases, which, after all, were at the

time known to be the primary cause of global warming. Since that

period perhaps we have gained enough wisdom and knowledge

through the scientific process to understand that not all the agents

forcing the climate system cause an equal response in terms of climate, precipitation, and temperature per unit forcing.

If there were one thing that I could recommend be done differently in the next round of treaties, it would be to consider the

response of the climate system, to look at the temperature effects

of each forcing agent by sector and by time scale.

To reiterate, one of the conclusions I think that the panel has

shared is that black carbon presents a unique opportunity because

it can offset or mitigate warming on a very quick time scale, giving

us an additional decade or perhaps two to struggle with the more

complex emissions such as carbon dioxide that our infrastructure

depends on to such a critical degree.

Mr. HODES. Thank you.

Dr. Schwartz.

Mr. SCHWARTZ. Thank you very much for the opportunity.

I agree with basically what has been said. I think that we are

relatively much more uncertain about black carbon than about CO2

in terms of climate change and stuff, but I think the existence of

very substantial health benefits means we can afford to make that

investment. It is justified on the health, alone, and so we can live

with that uncertainty and incorporate it into one of the strategies

going forward.

Mr. HODES. I thank you all very much.

Mr. Chairman, thank you for the additional time.

Chairman WAXMAN. Thank you, Mr. Hodes, for your questions.

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Let me ask a few more questions, if I might.

Dr. Zender, if we look at the Arctic where we can see the dramatic level of destruction that is taking place in a timeframe that

no one imagined, and we try to attribute how much of that warming is due to the black carbon, can you give us any estimate? Is

that possible?

Mr. ZENDER. I think it is possible based on the results of our best

understanding, which come from these general circulation or climate models which incorporate, as closely as they can, all processes

known to contribute to the problem in the Arctic. My best guess is

that up to 30 percent of the warming in the Arctic since pre-industrial can be attributed to manmade black carbon injections into the

Arctic. This is an uncertain number and certainly greenhouse gases

are playing the dominant role, especially CO2.

What is interesting at the Arctic and why it is changing so rapidly is that it is more susceptible, more vulnerable to a tipping

point situation because you have the ice that, once it melts, uncovers these dark surfaces.

So the current data showing record sea ice retreat, showing acceleration of glacial outpouring into the oceans around southern

Greenland and around the west Antarctic ice sheet, are all indicators that you would expect to see from these same models that give

us these estimates; that the models are doing something right

there. They have a degree of skill there.

So my best estimate would be that sitting on top of a dominant

greenhouse gas contribution is the role of short-lived pollutants,

not only including black carbon in the Arctic, but also ozone and

methane. Some of those are clearly causing quit a bit of warming

in the Arctic.

Chairman WAXMAN. We hear a lot about tipping points with regard to global warming. You are talking about the tipping point in

the Arctic, which is quite sobering, but we have heard from some

researchers that tell us that if we don’t deal with carbon emissions

overall we are going to have a tipping point so that when we start

dealing with it seriously the time lag before we see the benefits

may be too late to stop irreversible damage.

Do any of you want to comment on that? Dr. Jacobson.

Mr. JACOBSON. Sir, I guess the three major tipping points are

one, with regard to the coral reefs, like if we raise the temperatures another one degree celsius you might bleach the corals, and

that would cause a lot of irreversible damage to fisheries, for example.

And then the second is the sea level rise due to, just as we are

talking, if you melt all this Arctic ice, and in particular if you go

down to the Antarctic and the west Antarctic ice sheet goes, then

you are going to raise the sea level significantly. But in the case

of the Arctic, because of the positive feedback, once you melt that

ice you are warming the surface more, and make it harder to cool

down.

This is a serious problem with the Arctic. Once you have melted

that ice, you have all your sunlight warming the surface, so I am

really concerned about that.

But I also want to point out that black carbon has a bigger effect

on the Arctic than it does kind of on the rest of the world per unit

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meter or some kind of unit like that, but so does CO2. CO2 actually

also has a larger effect on the Arctic and over snow and sea ice

compared to over land surfaces. You can see that just in numerical

simulations over Russia and over the Arctic and over even in other

places where there is snow. So I am concerned about the tipping

point, but also I think you really need to control the CO2 and the

black carbon simultaneously, because both of them have super linear effects over snowy or highly reflective surfaces.

Chairman WAXMAN. So as we look at this global warming problem, if we deal with the black carbon we will get a more immediate

benefit, maybe delay the tipping point that we are fearful about,

and give us some additional time to avoid some of the irreversible

damage to the planet that has been predicted?

Mr. JACOBSON. Yes. It would give additional time, but I guess I

wouldn’t want that to be translated into, OK, then we don’t have

to control the CO2.

Chairman WAXMAN. Right.

Mr. JACOBSON. Which is the concern. It really needs to be done

simultaneously I think with CO2 controls. It is not really an either/

or.

Chairman WAXMAN. OK. Thank you.

Mr. Davis, did you have any other questions?

Mr. DAVIS OF VIRGINIA. No. I just want to thank the panel for

helping to illuminate us on this situation, and I hope that we can

respond accordingly.

Thank you, Mr. Chairman.

Chairman WAXMAN. Thank you.

Ms. Norton, did you want to ask some questions?

Ms. NORTON. No questions.

Chairman WAXMAN. No questions. OK.

This has been a terrific education for us and we hope to share

this hearing record with the rest of our colleagues in the Congress

and others who are looking at the whole question of how do we

come to terms with the global warming problems. I think you make

a compelling case that we need to look at controlling black carbon

as part of that solution.

I want to do some housekeeping.

I want to ask unanimous consent that all members of this committee will have an opportunity to enter an opening statement in

the record if they wish to.

Second, I would like to be able to give the opportunity to Members to submit questions in writing to the panel and have you respond in writing to them if you would.

I thank you so much. I think you have done an excellent job, and

I think this is an important hearing for the debate that we are continuing to have in the Congress of the United States. Thank you.

That concludes our business and the committee stands adjourned.

[Whereupon, at 11:50 a.m., the committee was adjourned.]

[The prepared statement of Hon. Diane E. Watson follows:]

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