Global WarmingGlobal Warming

Dennis SilvermanDennis Silverman

Physics and AstronomyPhysics and Astronomy

U C IrvineU C Irvine

Global Warming Global Warming

• Greenhouse gases: COGreenhouse gases: CO22 , methane, and nitrous , methane, and nitrous oxideoxide

• Already heat world to average 60° F, rather than Already heat world to average 60° F, rather than 0° F without an atmosphere0° F without an atmosphere

• How greenhouse gases workHow greenhouse gases work• Increased COIncreased CO22

has raised temperature 1.2° Fhas raised temperature 1.2° F• The present radiation imbalance will cause The present radiation imbalance will cause

another 1° F heating by 2050, even without more another 1° F heating by 2050, even without more greenhouse gas emissions.greenhouse gas emissions.

• Recent cleaning of air is causing the earth’s Recent cleaning of air is causing the earth’s surface to be hotter and brighter.surface to be hotter and brighter.

• Stabilizing the amount of COStabilizing the amount of CO2 2 would require a would require a reduction to only 5% to 10% of present COreduction to only 5% to 10% of present CO22 emissionsemissions

Definitive Evidence of Rapid 1.2° F Temperature Rise over the Last Century

Carbon Dioxide Concentrations are low in glacial periods and higher in warmer interglacial periods

However, concentrations now are higher than at any time in the last 450,000 years.

In the insert is the dramatic growth over the last 50 years.

Temperature and CO2 CorrelationTemperature and CO2 Correlation

The last 160,000 The last 160,000 years (from ice years (from ice cores) and the cores) and the next 100 years:next 100 years:temperature (red) temperature (red) tracks COtracks CO22

(green).(green).

Time (thousands of years)Time (thousands of years)160160 120120 8080 4040 NowNow

––1010

00

1010

100100

200200

300300

400400

500500

600600

700700

COCO22 in 2100 in 2100(with business as usual)(with business as usual)

Double pre-industrial CODouble pre-industrial CO22

Lowest possible COLowest possible CO22

stabilisation level by 2100stabilisation level by 2100

COCO22 now now

Temperature Temperature

difference difference

from now °Cfrom now °C

CO

CO

22 c

once

ntr

ati

on

(ppm

) c

once

ntr

ati

on

(ppm

)

Adding Climate Model Projections for the next hundred years(new analysis expected in Feb.)

Q: What is today’s anthropogenic Radiative Forcing ?

Temperature comparison with and Temperature comparison with and without greenhouse gases and sulphur without greenhouse gases and sulphur (NCAR/DOE)(NCAR/DOE)

NCAR/DOE conclusions on temperature NCAR/DOE conclusions on temperature modelsmodels

• ““Solar activity Solar activity contributed to a warming trend contributed to a warming trend in global average temperature from the 1910s in global average temperature from the 1910s through 1930s. through 1930s.

• As industrial activity increased following World As industrial activity increased following World War II, sun-blocking War II, sun-blocking sulfates and other sulfates and other aerosol emissions aerosol emissions helped lead to a slight helped lead to a slight global cooling from the 1940s to 1970s.global cooling from the 1940s to 1970s.

• Since 1980, the rise in greenhouse gas Since 1980, the rise in greenhouse gas emissions from emissions from human activity has human activity has overwhelmed the aerosol effect to produce overwhelmed the aerosol effect to produce overall global warmingoverall global warming. “. “

Global Warming EffectsGlobal Warming Effects

• Predicted Global Warming of 5°F will affect everyone in Predicted Global Warming of 5°F will affect everyone in most structural aspects of society and in their costs.most structural aspects of society and in their costs.

• We don’t realize how our present housing, business, and We don’t realize how our present housing, business, and supply nets are closely adapted to our current climates. supply nets are closely adapted to our current climates.

• The major increase in temperature and climate effects such The major increase in temperature and climate effects such as rainfall, drought, floods, storms, and water supply, will as rainfall, drought, floods, storms, and water supply, will affect farming, year round water supplies, household and affect farming, year round water supplies, household and business heating and cooling energy. These may require business heating and cooling energy. These may require large and costly modifications.large and costly modifications.

• Some cold areas may benefit, and some hot areas will Some cold areas may benefit, and some hot areas will become unfarmable and costly to inhabit.become unfarmable and costly to inhabit.

• Recent projection: US agriculture would go up 4%, CA down Recent projection: US agriculture would go up 4%, CA down 15%.15%.

• Methane production seems to have stabilized (UCI result)Methane production seems to have stabilized (UCI result)• It is very misleading to portray the problem as a purely It is very misleading to portray the problem as a purely

environmentalist issue which affects only polar bears, a few environmentalist issue which affects only polar bears, a few Pacific islanders, and butterfliesPacific islanders, and butterflies. .

What can be said about the What can be said about the controversy?controversy?Here are some comments.Here are some comments.

• 17 national science academies have 17 national science academies have endorsed the conclusion of global warming endorsed the conclusion of global warming and its man-made causes.and its man-made causes.

• The Intergovernmental Panel for Climate The Intergovernmental Panel for Climate Change (IPCC, Change (IPCC, www.ipcc.chwww.ipcc.ch ), consulting ), consulting 2,500 scientists from 130 countries, will 2,500 scientists from 130 countries, will issued a new report on Feb. 2, after six issued a new report on Feb. 2, after six years, which states a 90-99% probability years, which states a 90-99% probability that warming since 1950 is human caused.that warming since 1950 is human caused.

• It has also concluded a >90% probability It has also concluded a >90% probability that temperatures will continue to rise.that temperatures will continue to rise.

What can we reasonably say about What can we reasonably say about fossil fuels and global warming?fossil fuels and global warming?• Global warming of 1° F has occurred in the past Global warming of 1° F has occurred in the past

century.century.• CO2 is a greenhouse gas and is way higher than it CO2 is a greenhouse gas and is way higher than it

has historically been. has historically been. • This is generated by human burning of fossil fuel, This is generated by human burning of fossil fuel,

but fortunately, half of that generated has been but fortunately, half of that generated has been absorbed in the carbon cycle.absorbed in the carbon cycle.

• Common sense, models of earth systems, and the Common sense, models of earth systems, and the correlation of warming with CO2 in ice ages, correlation of warming with CO2 in ice ages, indicate a direct effect between the two. indicate a direct effect between the two.

• Clearly, funding much more research on this is Clearly, funding much more research on this is clearly justified.clearly justified.

• Since we are going to run out of cheap fossil fuel Since we are going to run out of cheap fossil fuel this century, research on new energy sources, and this century, research on new energy sources, and plans to develop them are clearly called for.plans to develop them are clearly called for.

Arguments against global warming and Arguments against global warming and its man-made causesits man-made causes• 1. Global warming doesn’t exist1. Global warming doesn’t exist

– There is one location which hasn’t warmedThere is one location which hasn’t warmed– The Antarctic ice is growing in thicknessThe Antarctic ice is growing in thickness– Michael Crichton’s Michael Crichton’s State of FearState of Fear

• 2. Global warming is a natural cycle and not caused by 2. Global warming is a natural cycle and not caused by humans (and will go away?)humans (and will go away?)– Answer: But temperature changes must have a cause. All of Answer: But temperature changes must have a cause. All of

the known causes are included in the models, and human the known causes are included in the models, and human made causes dominate. Users of this symantic out never made causes dominate. Users of this symantic out never propose a “natural” cause.propose a “natural” cause.

• 3. Other objections to man-made origins:3. Other objections to man-made origins:– The dip in the 50s in the temperature curveThe dip in the 50s in the temperature curve– How can ppm of CO2 have any effectHow can ppm of CO2 have any effect– Breathing creates CO2Breathing creates CO2– The temperature always fluctuatesThe temperature always fluctuates– You can’t predict next week’s weather, so how can you …You can’t predict next week’s weather, so how can you …– Water vapor is more importantWater vapor is more important

Global Warming and PublicityGlobal Warming and Publicity

• 4. “Global warming is the greatest fraud 4. “Global warming is the greatest fraud perpetrated against the U.S.”perpetrated against the U.S.”– Sen. Inhofe, previous head of the Energy CommitteeSen. Inhofe, previous head of the Energy Committee– It is used by climate scientists so we will fund themIt is used by climate scientists so we will fund them

• Please refer to Please refer to www.realclimate.orgwww.realclimate.org for detailed for detailed scientific discussions of these challenges and of scientific discussions of these challenges and of recent research publications.recent research publications.

• Oil and energy companies are using the same Oil and energy companies are using the same organization to lobby against global warming as organization to lobby against global warming as brought you the cigarettes do not cause cancer brought you the cigarettes do not cause cancer campaign. They are also funding the dissident campaign. They are also funding the dissident scientists. See Union of Concerned Scientists scientists. See Union of Concerned Scientists report at report at www.ucusa.orgwww.ucusa.org..

Greenhouse Gases and the Kyoto Greenhouse Gases and the Kyoto TreatyTreaty• The treaty went into effect in Feb. 2005 to reduce greenhouse gas The treaty went into effect in Feb. 2005 to reduce greenhouse gas

emissions of developed countries to 5% below their 1990 level.emissions of developed countries to 5% below their 1990 level.• The U.S., as the largest CO2 emitter in 1990 (36%), will not The U.S., as the largest CO2 emitter in 1990 (36%), will not

participate because it would hurt the economy, harm domestic participate because it would hurt the economy, harm domestic coal production, and cost jobs.coal production, and cost jobs.

• China has signed the protocol, but as a developing country, it does China has signed the protocol, but as a developing country, it does not have to reduce emissions, and burns lots of coal.not have to reduce emissions, and burns lots of coal.

• In China’s defense: In China’s defense: – it only has ¼ the emissions of the US per capita; it only has ¼ the emissions of the US per capita; – ¼ of its GDP is for export;¼ of its GDP is for export;– it has significantly lowered its birth rate to one child per couple;it has significantly lowered its birth rate to one child per couple;– it is planning a large nuclear reactor program (20-30 or more);it is planning a large nuclear reactor program (20-30 or more);– it only has one private car per hundred inhabitants; andit only has one private car per hundred inhabitants; and– half of its population earns less than $2 per day;half of its population earns less than $2 per day;– the new three gorges dam is equivalent to several nuclear reactors in the new three gorges dam is equivalent to several nuclear reactors in

hydropower;hydropower;– they are asking for a 4% reduction per year in greenhouse gases but they are asking for a 4% reduction per year in greenhouse gases but

probably will not obtain it;probably will not obtain it;– they are trying to get sources of natural gas to use instead of coal.they are trying to get sources of natural gas to use instead of coal.

Comparative World CO2 Comparative World CO2 EmissionsEmissions

World Greenhouse Gas EmissionsWorld Greenhouse Gas Emissions

Effects of the Doubling of COEffects of the Doubling of CO22

• Doubling of CODoubling of CO2 2 projected by end of century, causing projected by end of century, causing approximately a 5° F increase in average temperature approximately a 5° F increase in average temperature (most rapid change in over 10,000 years)(most rapid change in over 10,000 years)– ~1.5 foot maximum sea level rise~1.5 foot maximum sea level rise– More storms and fiercer ones as illustrated by Atlantic More storms and fiercer ones as illustrated by Atlantic

hurricanes in 2005 with 10° hotter Caribbean sea hurricanes in 2005 with 10° hotter Caribbean sea temperaturestemperatures

– Loss of coral reefsLoss of coral reefs– Increase in tropical diseases since no winter coolness to kill Increase in tropical diseases since no winter coolness to kill

insectsinsects– 25% decline in species that cannot shift range25% decline in species that cannot shift range– Warming expected to be greater over landWarming expected to be greater over land– Hot areas expect greater evaporation from hotter winds Hot areas expect greater evaporation from hotter winds

causing droughtcausing drought– In the past, half of produced carbon has gone into storage as In the past, half of produced carbon has gone into storage as

in the oceans.in the oceans.– Heating of the surface ocean layer could stop ocean mixing Heating of the surface ocean layer could stop ocean mixing

and absorption into lower layers, thus shutting off carbon and absorption into lower layers, thus shutting off carbon absorption.absorption.

Global Warming EffectsGlobal Warming Effects• Global Warming is an average measureGlobal Warming is an average measure• Local warming or climate fluctuations can be very Local warming or climate fluctuations can be very

significantsignificant• Arctic is 5° warmerArctic is 5° warmer

– Ice cap is ½ the thickness of 30 years agoIce cap is ½ the thickness of 30 years ago– Partly due to natural cycle, partly man caused Partly due to natural cycle, partly man caused

global warmingglobal warming• Antarctic is 5° warmerAntarctic is 5° warmer

– Ice shelves over the sea are melting and breaking Ice shelves over the sea are melting and breaking off and may allow the 10,000 foot thick ice sheet off and may allow the 10,000 foot thick ice sheet over Antarctica to slide off the continent fasterover Antarctica to slide off the continent faster

– This would cause a sea level riseThis would cause a sea level rise• Rainfall is hard to predict. It could be increased or Rainfall is hard to predict. It could be increased or

decreased.decreased.• Drought can partly be caused by increased Drought can partly be caused by increased

evaporation at the higher temperature.evaporation at the higher temperature.

Global Warming Predictions for 2100 for Global Warming Predictions for 2100 for business as usual. The average increase is business as usual. The average increase is 5°F. Since we don’t live over the oceans, 5°F. Since we don’t live over the oceans, warming will be larger.warming will be larger.

Worldwide Glacial Melting, causing 2/3 Worldwide Glacial Melting, causing 2/3 of sea level rise of an inch a decade.of sea level rise of an inch a decade.

Global Warming effects in Global Warming effects in CaliforniaCalifornia• Summer temperatures rise by 4-8° F by 2100 Summer temperatures rise by 4-8° F by 2100

for low emission scenario: 8-15° F for higher for low emission scenario: 8-15° F for higher emissions.emissions.

• Heat waves will be more common, more Heat waves will be more common, more intense, and last longer.intense, and last longer.

• Spring snowpack in the Sierra could decline Spring snowpack in the Sierra could decline by 70-90%, as winters will be warmer.by 70-90%, as winters will be warmer.

• Agriculture, including wine and dairy, could Agriculture, including wine and dairy, could be affected by water shortages and higher be affected by water shortages and higher temperatures.temperatures.

• More forest fires.More forest fires.• Tree rings show that in eras of global Tree rings show that in eras of global

warming, megadroughts of decades hit the warming, megadroughts of decades hit the southwest US.southwest US.

CO2 Effects to Increase Over CO2 Effects to Increase Over CenturiesCenturies

Hasn’t yetHasn’t yet

added inadded in

HurricaneHurricane

Katrina inKatrina in

20052005

Permafrost melting by 2050 or 2080Permafrost melting by 2050 or 2080

• Depending on high Depending on high or low emissions or low emissions model, most of model, most of permafrost in permafrost in Canada, Alaska, Canada, Alaska, and Russia melt by and Russia melt by 2050 or 2080.2050 or 2080.

Worldwide increases in the average Worldwide increases in the average number of frost-free days by 2080number of frost-free days by 2080

Sea level rise has been 2 mm/yr for 50 Sea level rise has been 2 mm/yr for 50 years, but 3 mm/yr for the last decadeyears, but 3 mm/yr for the last decade

Florida with a 1 meter sea level rise or Florida with a 1 meter sea level rise or storm surgestorm surge

Nile and Sea Level RiseNile and Sea Level Rise

• At 0.5 m, 3.8 million At 0.5 m, 3.8 million population displaced population displaced (intermediate blue).(intermediate blue).

• At 1 m, 6.1 million At 1 m, 6.1 million population displaced population displaced (light blue).(light blue).

• The protective 1-10 The protective 1-10 km sand belt is km sand belt is eroding due to the eroding due to the Aswan dam.Aswan dam.

Ganges River delta and 1m sea level rise in Ganges River delta and 1m sea level rise in Bangladesh. 13 million displaced and 16% Bangladesh. 13 million displaced and 16% of rice production lost.of rice production lost.

• Similar 1 m sea Similar 1 m sea level rise in China level rise in China would displace 72 would displace 72 million people.million people.

Increase in Droughts (red) from 1948 to 2002.Increase in Droughts (red) from 1948 to 2002.The fraction of global land experiencing very dry The fraction of global land experiencing very dry conditions (-3) rose from about 10-15% in the early conditions (-3) rose from about 10-15% in the early 1970s to about 30% by 2002. Almost half of that 1970s to about 30% by 2002. Almost half of that change is due to rising temperatures rather than change is due to rising temperatures rather than

decreases in rainfall or snowfall.decreases in rainfall or snowfall.

IPCC 2007 Summary GraphsIPCC 2007 Summary Graphs

Historical Changes in Historical Changes in Greenhouse Gases Greenhouse Gases over 10,000 yearsover 10,000 years

• CO2CO2

• MethaneMethane

• NO2NO2

Blue shadedBlue shaded bands show the range from climate models using bands show the range from climate models using only the only the natural forcingsnatural forcings due to solar activity and volcanoes. due to solar activity and volcanoes. Red shadedRed shaded bands show the range from climate models using bands show the range from climate models using both natural andboth natural and anthropogenic forcings.anthropogenic forcings.

Global Surface Warming for This Global Surface Warming for This CenturyCentury

Economic Climate Models, Roughly in Economic Climate Models, Roughly in Order of Temperature Increases, High Order of Temperature Increases, High to Lowto Low• A2 Growing population, regional inequitiesA2 Growing population, regional inequities• A1 Peaking then declining population, world A1 Peaking then declining population, world

equity, high tech growthequity, high tech growth– A1FI Fossil fuel intensiveA1FI Fossil fuel intensive– A1B Balance of sourcesA1B Balance of sources– A1T Non-fossil fuel sourcesA1T Non-fossil fuel sources

• B2 Increasing population, regional inequities, B2 Increasing population, regional inequities, lower population growth than A2 and tech lower population growth than A2 and tech development than A1development than A1

• B1 Peaking then declining population, world B1 Peaking then declining population, world equity, non-material economy, clean solutionsequity, non-material economy, clean solutions

U.S. Carbon emission sourcesU.S. Carbon emission sources