Global Warming  Public perception  Physics of anthropogenic global warming  Key diagrams  Consequences  What can you do?

2 Do you think Global Warming is happening?

3 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

4 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.

5 State of the Climate 2009 Highlights (NOAA 2010)

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9 What causes Global Warming? Addition of greenhouse gases to atmosphere Main culprits are Carbon Dioxide, Methane, and water

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11 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

14 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

15 CS Fig

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17 Measured Changes in Outgoing Radiation

18 Similar to CS Fig Trees take up CO 2 Animals Produce Methane

19 CS Fig

20 CS Fig

21 Carbon emissions since 1800 Fig

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

23 Bubbles in glacial ice preserve air of past cent- uries: Tell us what CO 2 concentrations were like before the industrial revolution

24 Longer records Current CO 2 levels are well above range observed during recent geologic history associated with the ice ages Last Interglacial Current

25 Best evidence that recent warming is anthropogenic Data from Mann and others, Nature, 1998; Figure from IPCC 2001 Report Three years in the 1990’s are the warmest in the Northern Hemisphere, by far, of the last 400 years! Can’t account For recent warming Can’t account For prior warming Works!

26 Figure 15_19 CS Fig

27 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?

28 CS Fig

29 Fig Grinnell Glacier in Glacier National Park 1n 1914 and At present rates of melting, there will be no glaciers in Glacier National Park by 2030.

Global Temperatures projected to rise 3 to >7 °C IPCC 2009 Fig

31 USGCRP 2009 Climate Assessment Number of days over 100 degrees F

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33 Figure 15_25b

34 Figure 15_25a Fig a Models predict warmer, wetter winters and drier summers by Midwestern farm states will have summer climate similar to current summers in Louisiana or Texas. USGRP 2009.

35 CS Fig

36 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

37 Change in Lake Superior

38 MN Biomes at risk

39 We have a choice

40 How optimistic are you?

41 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

42 Scientific consensus Examining the Scientific Consensus on Climate Change EOS, VOLUME 90 NUMBER 3 20 JANUARY 2009

43 Somerville and Hassol, Physics Today, Oct. 2011

44 The End Back