Atmospheric Processes Involved in Global Warming

Top issues in science

Alternative energy

Stem cells & cloning

Global warming

Top issues in science

Nanoscience and nanotechnology

Genetically modified plants

Using animals in research

The public ignores many science issues

Pluto is NOT a planetFirst face transplant

Element 118 discovered

But not global warming...

A balanced presentation?

The “truth” in An Inconvenient Truth

Temperature trends

Temperature trends

Global Cooling fears

“There are ominous signs that the earth’s weather patterns have begun to change dramatically and that these changes may portend a drastic decline in food production ...”

Newsweek, April 28, 1975

Ten hottest years

Ten hottest years

Deadly heat waves

Extreme high temperatures

Not one of the world’s highest temperatures has occurredin the past 30 years!

U.S. National Oceanic and Atmospheric Administration

Hurricane warnings

Hurricane warnings

The Deadliest Hurricanes

Rosenberg Library, Galveston

Galveston hurricane, 1900: 8,000 killed

Bangladesh cyclone, 1970: 300,000 killed

Deadly weather disasters

• Yangtze River flood, 1931: 3.7 million killedYangtze River flood, 1931: 3.7 million killed• Vietnam flood, 1971:100,000 killedVietnam flood, 1971:100,000 killed• Great Iran Flood, 1954: 10,000 casualtiesGreat Iran Flood, 1954: 10,000 casualties• China typhoon 1912: 50,000 killedChina typhoon 1912: 50,000 killed• China typhoon 1922: 60,000 killedChina typhoon 1922: 60,000 killed• India drought 1914: 250,000 diedIndia drought 1914: 250,000 died• Chinese famine 1907: 24 million diedChinese famine 1907: 24 million died• Soviet Union drought 1921-1922: 3 million diedSoviet Union drought 1921-1922: 3 million died• Great Drought in western Sahara Desert 1968-Great Drought in western Sahara Desert 1968-

1973: 100,000 died from starvation and disease1973: 100,000 died from starvation and disease

Source: World Meteorological Organization

Deadly weather disasters

Big Questions

•Why do scientists disagree about the causes and effects of global warming?

•Why is the issue so complicated?

Kerry Emanuel: Phaeton’s Reins: The human hand in climate change

Boston Review, 2006 http://bostonreview.net/BR32.1/emanuel.html

Climate Change

• The earth is 4.5 billion years old.

• During the past 3,000,000 years, the earth has had both mild climates and ice ages.

Ice ages

Eccentricity (shape) of the earth’s orbit: 100,000 year cycle

Precession (wobbling) of the earth’s axis: 23,000 year cycle

Obliquity (tilt angle) of the earth’s axis: 100,000 year cycle

The Greenhouse Effect

~ 0.55 m

~ 10.0 m

Earth with no atmosphere

Earth and atmosphere together

Greenhouse gases

H2O: • The most important greenhouse substances (liquid and vapor).• H2O vapor absorbs infrared radiation warming• H2O liquid reflects sunlight into space cooling • H2O is constantly recycled between the atmosphere and the oceans• The concentration of water vapor is limited by temperature

CO2: • 2nd-most important greenhouse gas• absorbs infrared radiation warming• lifetime up to 200 years

Do clouds cool or warm the atmosphere?

Feedback processes

Positive feedback: an amplifying process

Negative feedback: a process that reduces itself

body heat

evaporation, cooling

REDUCED

Negative feedback: a reducing process

Ice-Albedo Feedback

Albedo: % of sunlight reflected.

White surfaces: large albedo. Dark surfaces: small albedo.

Ice-Albedo Feedback

Lots of ice in the Arctic

Ice-Albedo Feedback

Atmospheric temperatures increase

Sea ice melts

Albedo decreases

Earth absorbs more energy

Cloud feedbacks

Clouds reflect sunlight cooling

Clouds absorb IR radiation warming

Polluted clouds reflect more sunlight cooling

Sulfate (SO4) aerosols

sulfate aerosols reflect sunlight coolingsulfate aerosols cause more clouds to form coolingsulfate aerosols reduce the size of cloud droplets cooling

Chaotic system: • limited predictability• small differences increase quickly

Parameterization

Current status

So what should we do?• Elect politicians who understand science• Conserve the earth’s resources as much as you can• Pollute as little as you can• Remember that popular movies and books like

The Day After Tomorrow and State of Fear are entertainment,

not science.

What else?• Read what the scientists write (like the IPCC report:

www.usgcrp.gov/usgcrp/links/ipcc.htm)• Be skeptical• Trust your own opinion more than Hollywood’s,

Michael Crichton’s, or even Al Gore’s• Enjoy all the beautiful things in life• Have a nice day!