How Humans Impact Earth

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How Humans Impact Earths Radiation Balance

• Global Warming
• Ozone Layer Destruction

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Greenhouse Gases (like carbon dioxide) are like a
rechargeable battery for heat
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Global Warming A Preview in Classroom Resource
Movies
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What are greenhouse gases?
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Always ask in climatic change What has happened
in the past?
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Always ask in climatic change What has happened
in the past?
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Eocene Warmth
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Eocene Arctic was ice free
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Ice Age Fluctuations Never above 300 ppm (parts
per million)
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Classroom Resources
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CO2 helped warm Ice Age Earth
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Warming continued as civilizations flourished in
the Holocene (last 10,000 years), then cooled
with the sun in the Little Ice Age
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Warm Periods in the Holocene were wetter in
Monsoon Asia
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Big Questions over Trends and whether natural or
human caused
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Classroom ResourceWhy is theStarting point
100 years ago? Industrial revolution? or After
Little Ice Age?
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Graphs starting point
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Change from Little Ice Age and lower Solar Output?
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Story is complicated by type of radiation
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Wild cards organic inorganic aerosols (dust,
pollution) cooling influence
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So what happens if coal pollution is reduced?
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Will we get complacent in the next century,
causing massive trouble in 50 years?
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Predictions Vary
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How much of the warming is due to urban heat
island?
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Where are the thermometers?
Rural Kitt Peak
Urban growthPhoenix
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Always the problem sorting out cause (GHG,
Solar, Urban) from the effect (warming in some
places)
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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?

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Potential Impacts There will be Winners and
Losers, just VERY hard to predict with models
(good to try, just nobody really believes them)
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Winner Plant Productivity
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Plants love elevated CO2
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Winner longer northern growing seasons for wheat
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Winner India avoids drought from Cool Earth
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Long Record

• Warm
• Earth
• Favors
• Wetter
• Asian
• Monsoon

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Winner More Tropical Rain
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Loser the Arctic (Classroom Resource Movie)
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Loser close to shore
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Compilation and Analysis in Science October
2005Read scalecentimeters
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So why show Florida under water?
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Real Evidence Not sure if big ice sheets are
melting
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Stakes are high for low-lying places
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Agriculture Predictions of Losers in Lower
Latitudes
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Other possible effects (written by those favoring
a need for quick action)
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... climate models give no consistent indication
whether tropical storms will increase or decrease
in frequency or intensity as climate changes
neither is there any evidence that this has
occurred over the past few decades.
More Hurricanes?
IPCC, 1990 (p. xxv)
Changes globally in tropical and extra-tropical
storm intensity and frequency are dominated by
inter-decadal and multi-decadal variations, with
no significant trends evident over the 20th
century.
IPCC, 2001, p. 5
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, 2007, p. 6
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Overall, there is no evidence that extreme
weather events, or climate variability, has
increased in a global sense, through the 20th
century, although data and analyses are poor and
not comprehensive.
Houghton et al., 1996, IPCC, p. 173
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"We are becoming more vulnerable to natural
disasters because of trends of our society rather
than those of nature. In other words, we are
placing more property in harm's way."
van der Vink et al., 1998, EOS, p. 537
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Extreme chanceReduceGulf Stream
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Not tomorrow!
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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

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Classroom Resource
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Extreme Solution
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• It all comes
• down to
• Keeping
• Earths
• radiation in
• balance

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Time Special Report
Understand difference between science media spin
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Human Impact on Radiation BalanceIgnored by the
Media Ozone Crisis
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Why media ignores? Fear of chemistry?
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Or not understand completely different problems?
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Positive Feedback Started Buildup
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Ozone Still Made in Lower Latitudes
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Classroom Resource
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First question has Earths biosphere survived
past reduction in ozone?
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Classroom Resource
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Fear is damage by UV radiation
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Whats the crisis? We add more chlorine to the
stratosphere
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Classroom Resources
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Polar Stratospheric Clouds Key
Classroom Resource
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Creates Antarctic Ozone Hole
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Classroom Resources
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Keeps getting worse
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Arctic less problematic because warmer (less
polar stratospheric clouds) except in cold years
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We add other ozone-destroying agents
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Politics predictions ignore legal and illegal
cheating
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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.