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Global Warming -- What It’s All About A Quick Overview.

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1 Global Warming -- What It’s All About A Quick Overview

2 The Main Points Carbon dioxide (CO 2 ) is a greenhouse gas (Tyndall 1859). CO 2 is rising (Keeling 1958, 1960). The new CO 2 is coming from artificial sources (Suess 1955, Revelle and Suess 1957). The Earth is warming (NASA GISS, Hadley CRU, UAH, RSS, etc., etc.). The warming correlates with the rise in CO 2 (me).

3 Fourier 1824 Sunlight is not enough to keep the Earth as warm as it is. The atmosphere is keeping the Earth warm.

4 Tyndall 1859 The major greenhouse gases in Earth’s atmosphere are water vapor (H 2 O) and carbon dioxide (CO 2 ). They pass sunlight but absorb infrared light.

5 How Does the Greenhouse Effect Work? Greenhouse gases (GHGs) pass sunlight, which heats the ground. The warm ground radiates infrared (IR) light. GHGs absorb the IR. The GHGs warm up and radiate IR themselves -- some of it right back down to the ground. You’ve got both sunshine and “atmosphere shine” warming the Earth’s surface.

6 Arrhenius 1896 By burning oil and coal, industry is pouring CO 2 into the atmosphere. This is going to warm the Earth’s surface.

7 Keeling et al. 1958 and following Ambient air samples were taken every day starting in 1958 and analyzed for their CO2. It became clear right away that CO2 was rising every year. Observations all over the world confirmed Keeling et al.’s findings.

8 Manabe and Strickler 1964 You can simulate the Earth’s atmosphere as a series of stacked layers. You can then predict how a change in greenhouse gases will affect the Earth’s temperature.

9 NASA 2009 The Earth’s average temperature has been estimated for the years 1880-2009 from a variety of measurements.

10 How Do We Know the Earth is Warming? Temperature readings: Land surface stations, sea surface readings, borehole readings, balloon radiosonde readings, satellite measurements. Melting glaciers and ice caps. Tree lines moving toward the poles. Earlier hatch dates for eggs of fish, insects, frogs, and birds. Earlier bloom dates for flowers and flowering trees. Incursion of tropical diseases into temperate zones.

11 Levenson 2009 (he said grandiosely) Temperature correlates closely with airborne CO 2 for the years 1880-2008 (r = 0.874 for dT and ln CO 2 ).

12 Why Do We Care? Increased drought in continental interiors. More violent weather along coastlines. Sea-level rise--potential loss of trillions of dollars worth of infrastructure. Glacier retreat deprives 1 billion people in Asia and Latin America of fresh water. “Environmental refugees.”

13 Human Agriculture May Collapse In 1970, 12% of the world’s land was “very dry” (Palmer Drought Severity Index) at any one time. Now it’s 30% and rising (Dai et al. 2004). Australia has lost a third of its agricultural production in the past few years.

14 Can We Stop It? Not completely. Some warming is still “in the pipeline” whatever we do. But the more we mitigate it, the more damage we can avoid. The longer we wait, the worse it gets. If we wait too long, the warming may trip geophysical feedbacks (e.g. release of methane clathrates in permafrost and seabed sediments) which will make things much, much worse.

15 What Can We Do? Stop burning fossil fuels. Generate power from sunlight, wind, geothermal energy, and biomass fuels. Stop tearing down forests. Conserve--go to higher-mileage cars, build and use more mass transit, insulate buildings, recycle, don’t waste power.

16 Further Resources Spencer Weart 2003. “The Discovery of Global Warming.” Available on-line: S. George Philander 1998. “Is the Temperature Rising?” RealClimate--A climate blog run by climate scientists: My own climatology site: To get into the heavy and frightening math: John T. Houghton 2002. “The Physics of Atmospheres.” Or: Grant W. Petty 2006. “A First Course in Atmospheric Radiation.”

17 References Arrhenius, S.A. 1896. “On the Influence of Carbonic Acid in the Air upon the Temperature of the Ground.” Phil. Mag. 41, 237-275. Dai, A., Trenberth, K.E., and T. Qian 2004. "A Global Dataset of Palmer Drought Severity Index for 1870– 2002: Relationship with Soil Moisture and Effects of Surface Warming." J. Hydrometeorol. 1, 1117-1130. Fourier, J.-B. J. 1824. “Memoire sur les Temperatures du Globe Terrestre et des Espaces Planetaires.” Annales de Chemie et de Physique 2d Ser. 27, 136-167. Keeling, C.D. 1958. "The Concentration and Isotopic Abundances of Atmospheric Carbon Dioxide in Rural Areas." Geochimica et Cosmochimica Acta, 13, 322-334. Keeling, C.D. 1960. "The Concentration and Isotopic Abundances of Carbon Dioxide in the Atmosphere." Tellus 12, 200-203. Manabe, S. and R.F. Strickler, 1964. "Thermal Equilibrium of the Atmosphere with a Convective Adjustment." J. Atmos. Sci. 21, 361-385. Revelle, R. and H.E. Suess 1957. "Carbon Dioxide Exchange between Atmosphere and Ocean and the Question of an Increase of Atmospheric CO 2 During the Past Decades." Tellus 9, 18-27. Suess, H.E. 1955. “Radiocarbon Concentration in Modern Wood.” Sci. 122, 415-417. Tyndall, J. 1859. “Note on the Transmission of Radiant Heat through Gaseous Bodies.” Proceed. Roy. Soc. London 10, 37-39.

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