Transcript GEOL 1130 Global Warming

Global Warming
Public perception
Physics of anthropogenic global
warming
Key diagrams
Consequences
What can you do?
Do you think Global Warming is
happening?
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Americans’ Top 4 Gaps in
Understanding Climate Change
1. It’s happening now
2. It’s us
3. We have a choice
4. Scientists agree
Results of recent study by the Yale Project on Climate Change Communication
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It’s happening now
• 2011 was the 35th year in a row that the
global temperature was above average.
• That means half of all Americans have
never lived through a year that was below
average.
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State of the Climate 2009 Highlights (NOAA 2010)
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State of the Climate 2009 Highlights (NOAA 2010)
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State of the Climate 2009 Highlights (NOAA 2010)
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State of the Climate 2009 Highlights (NOAA 2010)
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What causes Global Warming?
• Addition of greenhouse gases to
atmosphere
• Main culprits are Carbon Dioxide,
Methane, and water
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Basic Physics
• Greenhouse gases trap heat in Earth’s
atmosphere
• Greenhouse gas concentrations have
risen
• Trapped radiation has been measured
• Planet will warm!!!!
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Heat-Trapping Blanket
NASA, handweaver.com
It’s us
• Half of human CO2 emissions are added
to atmospheric CO2 concentrations each
year
• Since 1958, CO2 concentrations have
risen from 315 ppm (parts per million) to
392 ppm in 2011 (about 2 ppm per year)
• Other greenhouse gases have risen as
well
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CS Fig. 15.17
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Measured Changes in Outgoing Radiation 1970-1997
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Animals
Produce
Methane
Similar to CS Fig. 15.20
Trees take up
CO2
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CS Fig. 15.19
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CS Fig. 15.20
2020
Carbon emissions since 1800
Fig. 15.20
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Has the burning of
fossil fuels resulted in
increased CO2
concentrations in the
atmosphere?
Yes!
-Measurements of air in Hawaii
-Measurements of ancient air
preserved in ice
Bubbles in glacial
ice preserve
air of past centuries:
Tell us what CO2
concentrations
were like before
the industrial
revolution
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Longer records
Current
Current
CO2 levels
are well above
range observed
during recent
geologic
history
associated with
the ice ages
Last
Interglacial
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Best evidence that recent
warming is anthropogenic
Three years in the
1990’s are the
warmest in the
Northern Hemisphere,
by far, of the last
400 years!
Data from Mann
and others,
Nature, 1998;
Figure from
IPCC 2001
Report
Can’t account
For recent warming
Can’t account
For prior warming
Works!
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Figure 15_19
CS Fig. 15.21
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Consequences
• Planet will warm
– High latitudes will warm more than low
latitudes
• Sea level will rise
• Questions:
– How fast will warming and sea level rise
occur?
– How will Earth’s weather patterns be
affected?
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CS Fig. 15.18
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Fig. 15.24 Grinnell Glacier in Glacier National Park 1n 1914 and 1998.
At present rates of melting, there will be no glaciers in Glacier National Park
by 2030.
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Global Temperatures
projected to rise
3 to >7 °C
IPCC 2009
Fig. 15.22
Number of days over 100 degrees F
USGCRP 2009 Climate Assessment
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Figure 15_25b
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Figure 15_25a
Fig. 15.25a Models predict warmer, wetter winters and drier summers by 2100.
Midwestern farm states will have summer climate similar to current summers in
Louisiana or Texas. USGRP 2009.
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CS Fig. 15.26
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Change in Minnesota
“Recent research indicates a warming trend
in Minnesota. A study of the climate record at
Fort Snelling shows an increase of 2.9°F in
average annual temperature between the
1860s and 1987, almost three times the
worldwide average. Analyses of more than a
hundred temperature-depth profiles in North
America show that ground latitudes
comparable to Minnesota’s indicated ground
warming of up to 3.6°F.”
From “Playing with Fire, Global Warming in
Minnesota” 1999; data from Baker and Skaggs, 1989
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Change in Lake
Superior
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MN Biomes at risk
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We have a choice
http://www.geograph.org.uk/photo/764803
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How optimistic are you?
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An economist’s view
• Sir Nicholas Stern, former chief economist
of the World Bank
– “Scientific evidence is overwhelming: climate
change is a serious global threat and
demands an urgent global response.”
– Costs of climate change will be 5 to 20% of
global GDP
– Reducing greenhouse emissions will cost 1%
of global GDP
• $1 spent now could save $20 later in the century
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Scientific consensus
Examining the Scientific Consensus on Climate Change
EOS, VOLUME 90 NUMBER 3 20 JANUARY 2009
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Somerville and Hassol, Physics Today, Oct. 2011
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The End
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