# Presentation: 261772

## The realities and opportunities of climate change

***The realities and opportunities of climate change***

- The balance of evidence suggests that there is a discernible human influence on global climate. IPCC 2nd Assessment Report, 1996.
- There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activity. IPCC 3rd Assessment Report 2001
- Most of the observed increase in globally averaged temperatures since the mid-20th century is ***very likely**** *[>90% probability] due to the observed increase in anthropogenic greenhouse gas concentrations. IPCC 4th Assessment Report 2007

***S. Mulkey***
***February 2007***

## The problem: greenhouse gases absorb and re-radiate heat to the lower atmosphere.

**Notes:**
The gases in the atmosphere surrounding the earth act much the same way.  Incoming solar radiation passes through the atmosphere to the earth’s surface, but most of the outgoing radiation emitted from the surface of the Earth is absorbed by the greenhouse gas molecules in the atmosphere and reradiated back towards the earth. In other words, the greenhouse gases trap heat as it is reradiated from the earth back to space. The effect of this is to warm the earth’s surface. 

Water vapor and carbon dioxide are the 2 most abundant natural greenhouse gases.

 This natural greenhouse effect keeps the earth about 60°F warmer than it otherwise would be. Without the greenhouse effect, life as we know it would not be possible.

Note the absurdity of arguing that the “surface of the planet is not heating up because the IR is re-radiated to the  atmosphere. Convection and conduction maintain the link between the land and the troposphere.

Correlation Between CO2 Concentration and Temperature Change

Ice core samples show that there has been a very clear correlation between atmospheric CO2 concentrations (shown in blue) and the global temperature record (shown in yellow). In other words, on a millennial time scale, fluctuations of CO2 and temperature have roughly mirrored each other over the last 160,000 years. One can also see from this graph that the earth has, in the past, experienced some pretty major fluctuations in temperature and CO2 concentration.

Ice core studies reading back as far as 420,000 years ago yield the same results: CO2 fluctuated between 180 and 280 ppm (as in this graph) and changes in CO2 were strongly correlated with changes in temperature.

Significant points about the current situation:  First, the current level of atmospheric CO2 is already far higher than it has been at any point during this period; it is outside the bounds of natural variability seen in the climate record of the last 420,000 years.  When viewed from a long-term perspective, the rate of change in CO2 concentration is also unprecedented. 

## The greenhouse gases

- Relative importance

- Trends through 2002

## Slide 4

## “The greatest hoax ever perpetrated on the American people.” - Senator James Inhofe. 2005

## The scientific consensus

*The scientific consensus*

***June 2005***

## Observed warming

- IPCC AR4:
**“****Warming of the climate system is unequivocal....**
**[there is] very high confidence that the globally averaged net effect of human activities since 1750 has been one of warming”**

## Models predicted the effect of Pinatubo

***Models predicted the effect of Pinatubo***

*** ******Global temperatures rose 1.1 ******o******F over the 20******th****** Century.***
*** ******AR4 models predict temperature to increase 3.2 - 7.2 ******o******F by 2100 relative to 1980-1999. ***

## Greenhouse gases are higher now than in 650,000 years

## It is impossible to simulate the observed temperature rise without including anthropogenic forcing

**Notes:**
This is the prediction of temperature based on GCMs derived from first principles and applied to the prediction of climate during selected months of 1971 and 1972.

## Future shock

## Consequences: if carbon dioxide doubles relative to pre-industrial concentrations, temperatures will rise 3.5 - 8.0 oF

***Washington DC will change from having about 35 days above 90******o ******F to over 85 days per year by 2050***.

## Consequences: shift in hardiness zones reflect warmer climate 1990-2006

*Consequences: shift in hardiness zones reflect warmer climate 1990-2006*

## Green • = increasing

**Brown**** ****•**** ****= decreasing**

**Consequences:**
-  ***more precipitation in mid-latitudes ***
*** ******drier in the subtropics***
***major redistribution of surface water.***

## Consequences: increased drying cycle intensity

** ****The 1999-2002 national drought was one of the three most extensive droughts in the last 40 years.**
** ****In 2002, the Western United States experienced its second worst wildfire season in the last 50 years.**
** ****The period from April through June of 1998 was the driest three-month period in 104 years in Florida, Texas, and Louisiana.**
** ****Dry conditions produced the worst wildfires in 50 years in Florida in 1998.**
** **
** ****September 2001 to February 2002 was the second driest six-month period on record for the Northeast.**

## Consequences: extreme weather

**2004 - 1,717 tornados**

## Consequences: increased hurricane intensity

**     **

***Consequences: increased hurricane intensity***

**Annual power dissipation (PDI) by tropical cyclones compared to September sea surface temperature (SST).**** **Emanuel [Nature, 2005]

- AR4:
- Stronger hurricanes “likely” [> 66%]

## Consequences: decreasing terrestrial ice

**When North America was colonized by Western Europeans, Glacier National Park contained more than 120 glaciers. Presently there are 23 glaciers, and by 2075 there will be none.**

## Consequences: decrease in polar ice

## Consequences: sea level rise

**AR4: 7 - 23 inches by 2100, excluding effects of ice flow and carbon cycle feedbacks.**

## Consequences: amplification from defrosting the permafrost

** ****Official climate projections do not include CO****2**** and CH****4**** emissions from melting permafrost.**
-  **Because of this carbon release, warming will be faster than predicted.** **(Davidson & Janssens *****Nature***** 2006)**

## Slide 22

## Business as usual: reasonable expectations by 2075

-  Sea level at minimum 0.25 meters (about 10 inches) higher

-  200 million human ecological refugees - sea level rise & disasters

-  Agricultural zones will shift up to 10o north in N. America

-  Up to 35% of existing biodiversity committed to extinction

-  Loss of most coral reefs - ocean warming & acidification

-  Increased infectious disease in tropics - 800 million with malaria

-  Up to a third of the Amazon basin progressing to savanna

-  Warmer, wetter, greater precipitation intensity, stronger dry periods

-  400 million people living with water shortage

-  Global economic cost of inaction: $6.98 trillion **(by 2100; Stern report)**

-  Low crop yields & widespread hunger in developing world

## Rapid climate change: tipping points & uncertainties

-  How fast will Greenland melt? When will it be _committed_ to melt down?

-  What will be the Antarctic ice flow?

-  Will the Atlantic conveyor belt slow down and stop?

-  What is the ocean capacity to absorb heat and CO2?

-  What is the extent of amplification due to permafrost & sea ice melting?

## The climate imperative

- Prevent the climate system from passing a “tipping point” that leads to irreversible climate change.

## Regional changes in net primary productivity

## Effects of climate change on Florida health

## Climate change and vulnerability to storm surge

***Stephen  Mulkey 2007***

*Hurricane tracks since 1871*

*[The effects of global warming] ****“will emerge as if someone had subtly, but progressively, loaded a pair of dice.”**** - Kerry Emanuel 2005*

**Notes:**
Note that the current mild hurricane season is attributable to the oncoming El Nino. Ironically, El Nino is increasing in frequency, and this is likely due to global warming.

## Can we do it?

*William Chameides*

## Wedges for mitigation

*“**For every complex problem there is an answer that is clear, simple, and wrong.”*
**H. L. Mencken**

## We need at least 7 wedges

- William Chameides

## Opportunity: solar photovoltaic

- 52% of US solar exports go to Germany
- Germany installations = 8 times US installs

## Opportunity: how best to implement wedges in the US?

- Use market forces
- driven by “cap-and-trade”

- Climate change is serious business.

## Carbon markets make money

## “We have three choices - mitigation, adaptation, and suffering.” John Holdren, President AAAS

***Stephen  Mulkey ***
***2007***

- “We have three choices - mitigation, adaptation, and suffering.” **John Holdren, ****President AAAS**