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Explore the physics of anthropogenic global warming, public perception, and the consequences of climate change. Learn what you can do to make a difference.
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Global Warming Public perception Physics of anthropogenic global warming Key diagrams Consequences What can you do?
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
It’s happening now • 2011 was the35th year in a row that theglobal temperaturewas above average. • That means half of all Americans have never lived through a year that was below average.
What causes Global Warming? • Addition of greenhouse gases to atmosphere • Main culprits are Carbon Dioxide, Methane, and water
Basic Physics • Greenhouse gases trap heat in Earth’s atmosphere • Greenhouse gas concentrations have risen • Trapped radiation has been measured • Planet will warm!!!!
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
Animals Produce Methane Trees take up CO2 18 Similar to CS Fig. 15.20
Carbon emissions since 1800 Fig. 15.20
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 cent- uries: Tell us what CO2 concentrations were like before the industrial revolution
Last Interglacial Current Longer records Current CO2 levels are well above range observed during recent geologic history associated with the ice ages
Can’t account For recent warming Can’t account For prior warming Works! 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
Figure 15_19 CS Fig. 15.21
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?
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.
Global Temperatures projected to rise3 to >7 °C IPCC 2009 Fig. 15.22
Number of days over 100 degrees F USGCRP 2009 Climate Assessment
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.
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
We have a choice http://www.geograph.org.uk/photo/764803
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
Scientific consensus Examining the Scientific Consensus on Climate Change EOS, VOLUME 90 NUMBER 3 20 JANUARY 2009
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