**Emerging Climate Science Issues Breakout Session**

as summarized by

Margaret McCalla

National Oceanic and Atmospheric Administration (NOAA)/Office of the
Federal Coordinator

The Emerging Climate Science Issues Breakout session was divided into
two parts. In the first part of the breakout session, the panelists
presented their critique of Chapter 2 (Research Focused on Key Climate
Change Uncertainties). The second part of the breakout session was
devoted to questions and statements from the audience. The panelists'
presentations and audience questions/statements are summarized below.

**Part I - Panelists' Presentations**

The panel consisted of a moderator and five speakers. Panel members were

-   Dr. Robert Correll (moderator, Harvard University);

-   Dr. Alexander MacDonald (NOAA);

-   Dr. Warren Washington (National Center for Atmospheric Research);

-   Dr. V. Ramanathan (Scripps Institution of Oceanography and
    University of California at San Diego);

-   Dr. Michael Schlesinger (University of Illinois at
    Urbana-Champaign); and

-   Dr. Brian Flannery (ExxonMobil Corporation).

Part I - Panelists' Presentations

[Dr. Alexander MacDonald]{.underline}

Dr. MacDonald presented an overview of Chapter 2 and stated that since
we are stewards of the planet, we should know as much as possible about
the planet. He reminded the session participants that the strategic plan
time frame is 2 to 4 years. He noted that the chapter lists research
needs but does not prioritize those needs. He also reviewed the three
chapter focus questions which are listed below.

**(1) What aerosols are contributing factors to climate change and what
is their relative contribution?**

Dr. MacDonald pointed out that there is great uncertainty with the
radiative forcing associated with aerosols. He presented a graphic
showing that desertification is increasing and that dust storms formed
over Africa influence cloud formation. He also noted that these dust
storms transit the globe and can be seen over North America. Soot makes
the same transoceanic crossing. Using these occurrences as examples, he
stated that we live in a global environment and global observations are
very important.

**(2) What are the magnitudes and distributions of North American carbon
sources and sinks, and what are the processes controlling their
dynamics?**

Dr. MacDonald emphasized the need to strengthen existing carbon
measurement networks. He noted that there are problems with calculating
the magnitude of CO~2~ because there is a dearth of observations,
especially within the boundary layer. To fill this need, he suggested
that the U.S. embark on an observation program to measure these fluxes
with an array of observing platforms.

**(3) How much of the expected climate change is the consequence of
feedback processes?**

Dr. MacDonald stated that the feedbacks associated with clouds and water
vapor are not well known. Convection and compensating subsidence are
problems that we must address. The way clouds are treated in models will
result in significantly different model outputs. Different scenarios
will give different results. To deal with these uncertainties, he
recommends combined in situ and remotely sensed measurements of water
vapor for process studies with an emphasis on the tropics.

Another area of concern is the dynamic ice balance at the poles. Is the
amount of ice cyclical or not? We need to use advanced instruments to
show how the dynamics of ice cover varies.

Dr. MacDonald ended his overview of Chapter 2 by concluding that a
combination of research, observations, and modeling will bring us closer
to a better climate assessment.

[Dr. Warren Washington]{.underline}

Dr. Warren Washington began his presentation by listing the forcings of
the climate system as

• greenhouse gases (GHG)

• sulfate and carbon aerosols (direct and indirect effects)

• stratospheric and tropospheric ozone

• volcanic eruptions

• land surface and biomass burning

Dr. Washington stated that climate models have problems. Despite those
problems, the models "can still come close to reproducing the global
average temperature."

NCAR is trying to unravel the uncertainties most important for
understanding the observed climate record. He stated that when you add
the volcanic ash and solar forcing, you come close to understanding how
they contribute to the observed global average temperature record. You
also come closer to reproducing the global average temperature.

Dr. Washington continued his presentation by pointing out the problems
and gaps in Chapter 2. Some of the problems which Dr. Washington
highlighted were:

-   The chapter suggests that aerosols could offset the CO~2~ forcing.
    Dr. Washington said that this offset occurs at the regional level.
    It is not likely to be important globally.

-   The definition of "parameterized" as "simplified for incorporation
    in the models" is not quite right.

-   It is not clear what "improved estimates of global radiative energy
    losses arising from water vapor variability in the upper
    troposphere" means.

-   The National Carbon Program is excellent, but it is doubtful that it
    will provide "near-term information" to decision makers on a
    timescale of 5 years. Interannual and decadal variations may be
    difficult to establish on a 5-year time scale. The chapter may
    over-promise in this regard.

-   The "Feedback in the Polar Regions" section of Chapter 2 discusses
    important research, however, there does not seem to be large,
    coordinated field experiments planned. These types of experiments
    are essential to getting an integrated picture of the feedback
    mechanisms.

-   The "Research Needs" section of Chapter 2 highlights interesting,
    independent efforts. However, there is little emphasis on cloud,
    snow, and sea ice feedback mechanisms. Improved understanding of
    these mechanisms is critical for improved climate modeling in polar
    regions.

Dr. Washington enumerated gaps within Chapter 2. Some of those gaps
were:

-   There is no discussion of the impact of land surface changes and
    ozone changes on climate change.

-   A recent article in Science suggests that the indirect aerosol
    effect is smaller than previously estimated. This result needs to be
    tested by other researchers.

[Dr. V. Ramanathan]{.underline}

Dr. V. Ramanathan's presentation centered around four basic points:

\(1\) Air pollution and climate change are linked through aerosols and
tropospheric ozone.

> Dr. Ramanathan presented a framework for the interactions between
> global and regional processes. The inputs are greenhouse gases,
> regional and global tropospheric ozone, and air pollutant emissions
> (smoke, haze, CO, NO~x~, CH~4~, and hydrocarbons). Their interactions
> on a regional and global scale result in an ecosystem response and
> impacts on agriculture, water availability, and public health.

\(2\) The focus on the uncertainties due to aerosols should be done
regionally.

> Air pollution results in a large impact on regional climate. The
> regional changes can accumulate and result in global climate change.
> Therefore it is important to focus on regional observations.

\(3\) The tropics (within Africa, Asia, and South America) is a large
source for black carbon. For example, in Africa the black carbon comes
from biomass burning. These source regions should be defined.

> We are uncertain about the amount of black carbon by a factor of two.
> Black carbon emissions have increased considerably over the last 50
> years. We need to know the impact of black carbon on climate change.
> There are signals that we can observe. These signals can tell us where
> we should monitor black carbon.

\(4\) Water availability is the major environmental issue of this
century. There needs to be a focus on the hydrologic cycle.

> There needs to be an emphasis on the role of water vapor and the water
> budget on surface water. Additionally, there are some regions where
> copious amounts of extremely small aerosols are produced. These
> aerosols will reduce the number of aerosols that will develop
> raindrops. As a result, pollution due to aerosols is moving the clouds
> and rain away from these regions.

[Dr. Michael Schlesinger]{.underline}

Dr. Michael Schlesinger's presentation centered around the premise that
in order to reduce the uncertainty in climate sensitivity, consideration
must be given to variations in radiative forcing (especially from the
sun) and volcanoes. Chapter 2 paid little attention to the impact of
variations in solar forcing on climate change. He continued his
presentation by making four assertions and two conclusions. The four
assertions were:

Assertion 1: We will not be able to learn the value of the earth's
climate sensitivity (ΔT~2x~) from global climate models (GCMs).

Dr. Schlesinger illustrated his assertion by showing a graphic of the
range in ΔT~2x~ output from U.S., British, and Japanese CGMs.

Assertion 2: We can learn the value of ΔT~2x~ from the observed
temperature record and provide it to the GCMs as a target for them to
reproduce. Doing so will constrain their total net feedback.

Dr. Schlesinger illustrated his assertion by showing several graphics
depicting the relative contributions of human, volcanic, and solar
activity in observed temperature changes.

Assertion 3: The value of ΔT~2x~ from the observed temperature record
strongly depends on the radiative forcing.

Dr. Schlesinger provided a graphic showing how ΔT~2x~ varies depending
on the radiative forcing (e.g., GT, GTA, GTA1, GTAS, GTASV1, GTASV2).

Assertion 4: The value of ΔT~2x~ from the observed temperature record
has a probability distribution due to the noise in the climate system.

Dr. Schlesinger's two conclusions were as follows:

\(1\) To reduce the uncertainty in the estimated value of ΔT~2x~ we must
reduce the uncertainty of the radiative forcing not only by aerosols -
as focused on in the plan, but also by the sun and volcanoes.

\(2\) To reduce the uncertainty in the estimated value of ΔT~2x~ we must
observe and analyze in clever ways the earth's surface temperature.

[Dr. Brian Flannery]{.underline}

Dr. Brian Flannery called for a more structured U.S. program in climate
science. He used ExxonMobil as an example. Exxon Mobil is taking action
to reduce operational emissions and to promote technology innovations by
end users. ExxonMobil also conducts and supports peer-reviewed research
to advance climate science. He then asserted that successful development
and deployment of innovative, commercially viable technology is the only
path that addresses climate change risks and preserves and promotes
prosperity.

Dr. Flannery next articulated "well-known gaps" which limit climate
understanding. These gaps include:

-   climate processes (aerosols, clouds, surface hydrology, sea ice,
    moist convection)

-   availability of observations of climate variables and climate
    processes

-   inability to reliably forecast/model complex feedbacks

Given these gaps, Dr. Flannery concluded that in an issue filled with
fundamental uncertainty and no obvious long-term solutions, it is
essential to continue to make progress in climate science in order to
assess the pace of response and evaluate the effectiveness of proposed
response options (mitigation and adaptation). Simulations of climate
change show that we are dealing with chaotic behavior. Significant
natural climate variability exists. This natural variability is larger
than that reported in the 2001 IPCC report.

Dr. Flannery then articulated the elements of a more structured climate
change science debate. These elements include:

-   focused research programs that address specific, significant, known
    scientific uncertainties. Some of the areas that need to be
    addressed include clouds, aerosols, and water vapor. A portion of
    the U.S. budget should be targeted to address these uncertainties. A
    Federal agency should be assigned the lead in addressing these
    uncertainties and reporting back such information as the level and
    nature of the uncertainty as well as the policy relevance (e.g., to
    attribution, climate sensitivity, regional impacts, etc.).

-   enhanced technical and management capacity for an improved national
    infrastructure to observe, analyze, understand, and predict climate
    change. There is a need for better tools (computational and
    observational hardware) and management for science-based, objective
    policy analysis, and policy advice.

-   improved U.S. and international assessments of climate change. Dr.
    Flannery believes that the IPCC has become politicized. The U.S.
    should conduct a U.S.-oriented assessment of climate change. This
    assessment should be tailored to U.S. needs and issues. This
    assessment should incorporate U.S. research and development in areas
    of uncertainty.

Dr. Flannery concluded his remarks by saying it remains essential to
continue to fund blue-sky, curiosity or technologically driven
scientific research that may lead to unanticipated insight, results, and
breakthroughs.

**Part II - Audience Participation**

The questions and responses listed below capture the ideas expressed by
the audience and the panelists.

\(1\) Dr. Fred Singer (Science and Environmental Policy Project): When I
think about emerging issues in climate science, I think back 10 years
and remember issues of natural variability on a decadal time scale. To
what extent are the factors endogenous (e.g., the North Atlantic
Oscillation (NAO), the Pacific-Decadal Oscillation (PDO)) or exogenous
(sun's effect on climate variability)? Which is more important, the
endogenous or exogenous factors?

Response (from Dr. Schlesinger): Exogenous. It's compelling but not
understood.

\(2\) Pat Michaels (University of Virginia to Dr. Ramanathan): It is
important to understand if climate change is smooth or abrupt. What
processes should we look at that are missing from the GCM's that would
induce these non-linearities. Why haven't these processes been put in
our models?

Response (from Dr. Ramanathan): The well-known abrupt changes used to be
coupled strongly to El Nino. But that has decoupled. The Indian Ocean
has its own change (signal). So we should see if our models can simulate
this decoupling.

Response (from Dr. Washington): We are putting in more aerosols to get a
better handle on climate change; but error bars have not changed very
much in 5 years. But we must keep plugging away. We need to understand
the uncertainties and reduce them.

Response (from Dr. Schlesinger): We need to do more research.

\(3\) Charles Kennel (Scripps Institution of Oceanography): I would like
to poll the panel. There are other questions for basic research. Basic
research is the insurance against surprises. What is the most
significant thing we can do in the next 5 years to improve uncertainties
or to identify new significant questions?

Response (from Dr. Ramanathan): The Administration is addressing a time
frame of 2 to 4 years. So that is what this plan is addressing. Your
question should be addressed by the USGCRP.

\(4\) Charles Kennel (Scripps Institution of Oceanography): How do
biotic systems respond and how are they influenced? What is the role of
the ocean, for example?

Response (from Dr. Washington): We are seeing tremendous change in the
polar regions. This was stated in the chapter. There is a distinction
between basic and applied research. To anticipate surprises we need to
invest in basic research.

Response (from Dr. Flannery): We need to look at cloud physics and
aerosol actions and reactions to support our knowledge on known
uncertainties; to say what we know and what we don't know; to validate
and calibrate our models. But we also need to have basic research.

Response (from Dr. Schlesinger): I'm not so sure that 2 to 4 years is a
realistic time scale. Clouds and oceans are really lacking in the
models. So uncertainty is not going to evaporate over night.

\(5\) Tom Graham (U.S. Department of Energy): The borehole record shows
more variability than the Phillips-Jones record. So consider that
record. What is the assessment of that record? Should it be looked at or
is there something to disqualify this record?

Response (from Dr. Schlesinger): Not all models agree and are the same.
Not all models are right so not all can be believed.

\(6\) Blair Henry (University of North Dakota): I have been a member of
the national assessment for 10 years. I am pleased to see that this is a
follow-up from the National Academy of Sciences (NAS) 2001 study.
Aerosols was #7 on the NAS list. #1 was research in the area of fossil
fuels. Methane gas and fossil fuel-based feedback have not been
adequately addressed in this process.

Response (from Dr. Flannery): There is a clear issue about the sources
of future emissions. Those are important issues that are discussed by
other panels.

\(7\) Keith Dickson (NOAA): Chapter 2 emphasizes more sophisticated and
higher resolution models. Many different radiative forcings are also
emphasized in the chapter. Ensemble forecasts decrease uncertainties.
Where would you make the tradeoffs?

Response (from Dr. Washington): Models will be more complex (e.g., more
forcing, more resolution). All this means more computing needs. But
hopefully we will have better climate models to use in climate change
and assessments. But there are more fundamental issues with climate
models even with better models.

Response (from Dr. Schlesinger): The operational models need to run on
many scenarios with contemporary resolutions. The research modeling
needs to focus on higher resolution.

\(8\) Loris Dean (U.S. Department of Housing and Urban Development) :
With respect to haze, to what extent do we need to structure
cost/benefit analyses? We need to look at regional impacts and a
quantification of impacts of and on local and regional responses. What
can we achieve at the local and regional levels since some of the
impacts originate or are caused at the local and regional levels?

Response (from Dr. Ramanathan): Haze is not a regional issue. It's
transported globally. Warming is aggregated regional change. Models
don't have this type of regional modeling inputs or outputs. We need
data to get there along with greater model resolution. We need
resolution at 100 Km.

Response (from Dr. Flannery): Most developing countries don't think
climate change is a priority issue. We can look at climate change and
pollution at the regional level. Then the developing countries will get
interested.

\(9\) Dee Ann Divis (UPI): At what point will we have enough data to
make a decision vs. taking no action until it's too late?

Response (from Dr. Schlesinger): We need an adaptive policy that is
robust enough to take into account uncertainties.

Response (from Dr. Washington): Secretary of the Treasury O'Neill asked
the same question. There is no safe and unsafe level. It's more like a
continuum. You need to address issues of global warming before you know
everything.

Response (from Dr. Flannery): Knowing what we know, what is the right
action? The scope of the required action is large. It will take a
revolution in technology. There is a large amount of R&D going on but no
promise that technology will deliver in the proper time frame. How much
do you do knowing what you know? Companies are taking mitigating actions
now.

\(10\) Paul Epstein (Center for Health and Global Environment): Are
there systemic parameters that we can model to know if rates of change
and variability in these parameters would foster rapid change?

Response (from Dr. Ramanathan): Black carbon modeling has shown that we
can put enough carbon in the atmosphere to decouple the ocean and
atmosphere. Then the climate variability takes a different track
(regime). The observed data would suggest that the monsoon has weakened.
The sulfate pollution in the west has been attributed to weakening the
monsoon. The problem is that we don't trust our models at the regional
level. This is a potential issue that I am thinking about.

Response (from Dr. Schlesinger): We are in the nascent stage of
climate/ocean modeling.

\(11\) Bill Orr (National Alternative Fuels Foundation): My compliments
to Dr. Flannery for his views about being an advocate for basic research
to enhance our knowledge.

\(12\) Kerry Pressler (U.S. Department of Commerce): There is nothing in
the strategic plan regarding a standard needed for aerosol measurements
and modeling to support validation of models.

Response (from Dr. Ramanathan): There is tremendous uncertainties. For
black carbon there is a factor of 2 with respect to uncertainty.

\(13\) Jim Patton (Battelle): Will ultrafine particles stay in the
atmosphere?

Response (from Dr. Ramanathan): With respect to ultrafine particles'
impact, we don't think climate models deal with those. We need to
understand how ultrafine particles become aerosol particulates.

\(14\) Gad Levy (Northwest Research Associates): Modeling philosophy
about deterministic models will not answer all the questions. What about
using probabalistic models to help limit the uncertainties? We could
combine probablistic and deterministic models (a hybrid).

Response (from Dr. Schlesinger): This is a good area to explore.

\(15\) Steve Goldberg (Argonne National Laboratory): Lay people read
these documents. Be precise with your language. What is the definition
of "significant?" How far are we away from what we need to know?

Response (from Dr. Flannery): We can quantify enough to know that some
forcings are significant. There are others that we can't quantify.

\(16\) David Warrilow (Department for Environment, Food, and Rural
Affairs, UK): We need to step back and think why does this need to be
done. Is there a problem to be addressed? At what safe level can we
achieve stabilization is a most important question. How important are
the individual uncertainties and what are their impacts? A lot could be
achieved in that area and a lot can be accomplished within the
international community. A lot of these uncertainties can be constrained
so that we can look at them individually. We can assess impacts with a
risk assessment program.

\(17\) Glen Juday (University of Alaska): I want to nominate an emerging
issue - the Boreal Forest issue. This will be a major uptake of aerosols
in the future. There are multiple responses to uptake. This will take a
lot of site-based observations. So trying to come up with answers in the
next 2 to 4 years will be problematic. This is a dynamic, complex
problem.

Chuck Hakkarinen (Belmont, CA): The organization (CCRI) will be flooded
with requests to sponsor research initiatives. What is the management
strategy for dealing with these many requests?

Response (from Dr. Correll): Peer review mechanisms will sort out the
quality proposals.