How Humans Impact Earth’s Radiation Balance

Global Warming

Ozone Layer Destruction

Greenhouse Gases (like carbon dioxide) are like a rechargeable battery for heat

Global Warming: A Preview in Classroom Resource Movies

What are greenhouse gases?

Always ask in climatic change: What has happened in the past?

Always ask in climatic change: What has happened in the past?

Eocene Warmth

Eocene Arctic was ice free …

Ice Age Fluctuations: Never above 300 ppm (parts per million)

Classroom Resources

CO2 helped warm Ice Age Earth

Warming continued as civilizations flourished in the Holocene (last

10,000 years), then cooled with the sun in the Little Ice Age

Warm Periods in the Holocene were wetter in Monsoon Asia

Big Questions over Trends and whether natural or human caused

Classroom Resource:Why is theStarting point 100 years ago? Industrial revolution? or After Little Ice Age?

Graphs starting point

Change from

Little Ice Age and

lower Solar

Output?

Story is complicated by type of radiation

1365.0

1365.5

1366.0

1366.5

1367.0

1367.5

1368.0

1368.5

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Irra

dia

nc

e

TotalTotal UltravioletUltraviolet VisibleVisible InfraredInfrared0.00.0

0.10.1

0.20.2

0.30.3

0.40.4

0.50.5

0.60.6

0.70.7

Wild cards: organic & inorganic aerosols

(dust, pollution) cooling

influence

So what happens if coal pollution is reduced?

Will we get complacent in the next century, causing massive trouble in 50 years?

Predictions Vary

How much of the warming is due to “urban heat island”?

Where are the thermometers?

Rural Kitt Peak

Urban growthPhoenix

Always the problem: sorting out cause (GHG, Solar, Urban) from

the effect (warming in some places)

Satellite Record: least bias• Red line (used to be no evidence of

warming)

• Blue & Green (lower and middle troposphere) – warming is evident, but is it natural or us?

Potential Impacts: There will be Winners and Losers, just VERY hard to predict with models (good to try, just nobody really believes them)

Winner: Plant Productivity

Plants Plants love love

elevated elevated COCO22

Winner: longer northern growing seasons for wheat

Winner: India avoids drought from Cool Earth

Long Record

Warm

Earth

Favors

Wetter

Asian

Monsoon

Winner: More

Tropical Rain

Loser: the Arctic (Classroom Resource Movie)

Loser: close to shore

Compilation and Analysis in Science – October 2005Read scale:centimeters

So why show Florida under water?

Real Evidence: Not sure if big ice sheets are melting

Stakes are high for

low-lying places

Agriculture: Predictions of Losers in Lower Latitudes

Other possible effects (written by those favoring a need for quick action)

““... climate models give no consistent indication ... climate models give no consistent indication whether tropical storms will increase or decrease in whether tropical storms will increase or decrease in frequency or intensity as climate changes; neither frequency or intensity as climate changes; neither is there any evidence that this has occurred over is there any evidence that this has occurred over

the past few decades.”the past few decades.” IPCC, IPCC, 1990 (p. xxv)1990 (p. xxv)

““Changes globally in tropical and extra-tropical storm Changes globally in tropical and extra-tropical storm intensity and frequency are dominated by inter-intensity and frequency are dominated by inter-decadal and multi-decadal variations, with no decadal and multi-decadal variations, with no

significant trends evident over the 20significant trends evident over the 20thth century.” century.”IPCC,IPCC, 2001, p. 5 2001, p. 5

More Hurricanes?

“Multi-decadal variability and the quality of the tropical cyclone records prior to routine satellite observations in about 1970 complicate the detection of long-term trends in tropical cyclone activity. There is no clear trend in the

annual numbers of tropical cyclones.”IPCC,IPCC, 2007, p. 6 2007, p. 6

““Overall, there is no evidence Overall, there is no evidence that extreme weather events, that extreme weather events,

or climate variability, has or climate variability, has increased in a global sense, increased in a global sense,

through the 20through the 20thth century, century, although data and analyses are although data and analyses are poor and not poor and not comprehensive.”.”

Houghton et al., 1996,Houghton et al., 1996, IPCC, IPCC, p. 173p. 173

"We are becoming more "We are becoming more vulnerable to natural disasters vulnerable to natural disasters

because of trends of our because of trends of our society rather than those of society rather than those of

nature. In other words, we are nature. In other words, we are placing more property in placing more property in

harm's way."harm's way."

van der Vink et al., 1998,van der Vink et al., 1998, EOS, EOS, p. 537p. 537

Extreme chance:Reduce

Gulf Stream

Not Not tomorrow!tomorrow!

What to do?

• Set policies by governments?• Make personal choices (my choice is to

hang laundry on the line, ride my bike, use evaporative cooler) save money, while reducing my contribution to GHG

• Ask China and other societies not to industrialize? China generates more GHG than USA!

• Great setting for classroom lessons

Classroom Resource

Extreme Solution

It all comes

down to

Keeping

Earth’s

radiation in

balance

Time Special Report

Understand Understand difference difference

between science between science & media spin& media spin

Human Impact on Radiation BalanceIgnored by the Media: Ozone Crisis

Why media ignores? Fear of chemistry?

Or not understand completely different problems?

Positive Feedback Started Buildup

Ozone Still Made in Lower

Latitudes

Classroom Resource

First question: has Earth’s biosphere survived past reduction in ozone?

Classroom Resource

Fear is damage by UV radiation

What’s the crisis? We add more chlorine to the stratosphere

Classroom Resources

Polar Stratospheric Clouds Key

Classroom Resource

Creates Antarctic Ozone Hole

Classroom Resources

Keeps getting worse

Arctic less problematic because warmer (less polar stratospheric clouds) – except in cold years

We add other ozone-destroying agents

Politics & predictions ignore legal and illegal cheating

Imagery seen in this presentation is courtesy of Ron Dorn and other ASU colleagues, students and colleagues in other academic departments, individual illustrations in scholarly journals such as Science and Nature, scholarly societies such as the Association of American Geographers, city,state governments, other countries government websites and U.S. government agencies such as NASA, USGS, NRCS, Library of Congress, U.S. Fish and Wildlife Service USAID and NOAA.