Global Warming:

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Global Warming Fact, Fiction, and Best
Estimates By Scott Hewitt Dept. of Chemistry
Biochemistry California State University,
Fullerton Global Warming Teach-In Cal.
State Fullerton
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What is the greenhouse effect?
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• Does the greenhouse effect really exist?
• Without the greenhouse effect, the average
  temperature on Earth would be about -2 oF.
• The average global temperature is 59 oF.
• Yes, the greenhouse effect really does exist.

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Is global warming really occurring?
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• But in some parts of the world, it is very cold
  this winter?
• Regional weather fluctuates
• Global warming refers to the Earths
  temperature, averaged over the entire planet and
  the entire year not to the temperature at one
  location or at one time.
• Even the average global temperature will
  fluctuate, as it is based on so many variables.

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Is the global warming due to greenhouse
gases?
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Is the global warming due to greenhouse gases?
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Is the global warming due to greenhouse
gases? The average global temperature is
increasing as greenhouse gas concentrations
rise. Climate models cannot reproduce the
observed temperature trend without including the
rise in greenhouse gases. Yes, it appears
that global warming is mainly caused by the rise
in greenhouse gases (IPCC 90 certainty).
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Or, is global warming due to the sun? Since
1750, the average amount of energy coming from
the sun has stay fairly constant, but has
increased a little. If a more active sun were
the cause of global warming, we would expect
warming in all layers of atmosphere. However,
the upper atmosphere has cooled due to greenhouse
gases trapping of heat in the lower
atmosphere. It appears that solar radiation
only plays a small part in global warming (no
more than 10).
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What other evidence supports the idea that global
warming is occurring?
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Muir Glacier, Alaska, Aug. 1941 EMS outbreak
affected 1500 people who had been
administered a pharmaceutical tryptophan
solution. 27 people died.

Bruce Molnia, USGS
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Muir Glacier, Alaska, Aug. 2004
Previous Tryptophan Degradation Studies
Degradation products detected vary widely
depending on conditions and instrumentation
used. Extreme conditions used High
concentrations Non-natural oxidation
systems Greater than 40 loss of
tryptophan HPLC, GC-MS, and TLC used No
previous studies of commercial amino acid
solutions.
Bruce Molnia, USGS
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Extent of Arctic Sea Ice

Magenta line median Sept. 1979 - 2000 White
area Sept. 9, 2007 National Snow Ice
Data Center
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Ice Mass
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Greenland Meltwater
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Snowcap/Glacier on Mt. Kilimanjaro
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Sea Level Rise
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Why should we care about global warming? I like
the heat. ? Flooding of coastal
areas Changes in regional weather (hurricanes,
floods, droughts, heat waves, fires) Geographic
shift in flora and fauna (loss of biodiversity,
loss of agricultural productivity, more
infectious diseases, loss of fishing
stock) Economic loss (national security
issue)
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How much warming will occur by 2100? The IPCC
predicts warming of 2 to 10 oF over the next
century. There is significant uncertainty in
these numbers.
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What is the tipping point? When greenhouse
gas emissions rise high enough that runaway
global warming occurs due to ... snow absorbs
less sunlight than land methane burp when the
frozen tundra thaws when positive feedback
loops overwhelm the climate system (i.e., when
global warming causes more global warming, which
causes more global warming, )
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What do we need to do to protect
ourselves? Limit CO2 levels to 450 ppm, reduce
greenhouse gas emissions 60-80 by 2100 (Jim
Hansen, 2006) Reduce greenhouse gas emissions
80 by 2050 (Barack Obama, 2008) Reduce CO2
levels to 350 ppm (Jim Hansen, 2009) As to
where the tipping point is or as to how much we
need to reduce greenhouse gas emissions, we can
only estimate However, what is becoming clear
is that we need to act soon.
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Tomorrow, what will you do to build a
sustainable future?
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Acknowledgements Marlene Nang Dr.
Jason Hamilton, Ithaca College
www.noaa.gov www.jpl.nasa.gov CSUF
faculty, staff, students, and administrators My
contact info shewitt_at_fullerton.edu