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Global warming will make Europe cold and dry, abruptly,

Global warming will make Europe cold and dry, abruptly,. according to the National Research Council*. Why this opposite effect? To understand this, we need to look at.

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Global warming will make Europe cold and dry, abruptly,

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  1. Global warming will make Europe cold and dry, abruptly, according to the National Research Council*. Why this opposite effect? To understand this, we need to look at • the distribution of water on Earth, and water’s latent heat, to see how global warming is likely to affect the northern and southern hemispheres differently, and • the ocean currents that keep Europe unusually warm for its location. Europe currently has an unusually warmer and wetter climate for its high-latitude location. * SCIENCE & POLICY IMPLICATIONS OF ABRUPT CLIMATE CHANGE: National Research Council (National Academy Press, Washington DC: April 2002)

  2. Northern hemisphere is 60.7% sea and 39.3% land, while the Southern hemisphere is 80.9% sea and 19.1% land; and • ice accounts for a smaller proportion of water in the Northern hemisphere (0.47%) than in the Southern hemisphere (3.7%). Earth has a hemi-spherically asymmetric distribution of land and water. Oceans Icecaps, Sea-ice & glaciers N. Hemisphere 587.6 billion Km3 2.8 billion Km3 S. Hemisphere 782.4 billion Km3 30.1 billion Km3 1 Km3 = 262.4 billion gallons • water’s latent heat of fusion is 80 cal/gm, and its latent heat of evaporation is 585 cal/gm, i.e., the heat needed to evaporate a gram is water is enough to melt 7 times as much ice. Therefore, global warming should affect the Northern and Southern hemispheres in significantly different ways.

  3. The 20th century data reflect this, with Sources: (a) For temperature data: http://www.giss.nasa.gov/data/update/gistemp/graphs (b) For sea level data: T.P. Barnett, in CLIMATE CHANGE (IPCC Working Group Report: Cambridge University Press, 1990) • correlated rises, since 1900, of 0.6ºC in mean global temperatures and ~10 cm in the mean sea level worldwide; and • increased precipitation at higher latitudes, in the Northern hemisphere, and relative aridity at the lower latitudes, compared to • greater precipitation throughout the Southern hemisphere, but for ~20ºS. 8 Mean global temperatures relative to 1951-80 (ºC) Mean Sea level relative to 1951-70 (cm) 0 -8 Precipitation Change (1900-94) - 10% 0% 10% 40oN Oceans modulate the climate, irrespective of whether global warming is anthopogenic or not. 0o 40oS Land as the % of Earth’s surface area per 1º latitude band 0 0.5 1 Recomputed from the data in Thomas Karl, Neville Nicholls & Jonathan Gregory: The Coming Climate, Scientific American, May 1997

  4. A recent analysis of Earth’s heat balance* goes a step further, by quantitatively demonstrating that, during the latter half of the 20th century, changes in the ocean heat content have dominated the changes in Earth’s heat balance. • Much of this heat appears to have gone particularly into the warming of Atlantic waters. World Ocean (1.82x1023 J) Global Atmosphere (6.6x1021 J) Sea-Ice Melt (3.2x1021 J) Glacial Melt (9.2x1021 J) Surface 200 150 Heat Content Increase (in 1021 Joules) 100 50 0 * S. Levitus, J.I. Antonov, J. Wang, T.L. Delworth, K.W. Dixon & A.J. Broccoli: Anthropogenic warming of Earth’s climatic system. Science, 292: 267-270 (2001). 3 Km depth http://www.nodc.noaa.gov/OC5/WOA98F/woaf_cd/search.html

  5. Two kinds of currents transfer this heat across the oceans: • wind-driven surface currents like the Gulf Stream that carry warm tropical waters to the higher latitudes, and • the Global Conveyor Belt1 of thermohaline cir-culation that mixes all the surface and deep waters and is particularly sensitive to changes in the hydrological cycle2. 1 W.S. Broecker: “The great ocean conveyor”, Oceanography, 4: 79-89 (1991) and “Chaotic Climate”, Scientific American, Nov 1995. 2 S. Rahmstorf: Bifurcation of the Atlantic thermohaline circulation in response to changes in the hydrological cycle. Nature, 378: 145-149 (1995).

  6. The resulting change is likely to be abrupt*, • based on the evidence from Greenland and Antarctic ice cores, that the warming that began in the Younger Dryas started with the present Conveyor Belt and was a accomplished rapidly; which • raises the alarming possibility that Europe may suddenly revert to its Mini Ice Age (c. 1300-1900) in a matter of decades. Younger Dryas Data Sources: Alley et al., Nature, 362: 527-529 (1993); Grootes et al., Nature, 336: 552-554 (1993); Blunier et al., Nature, 394: 739-743 (1998). * P.U. Clark, N.G. Pisias, T.F. Stocker & A.J. Weaver: The role of the thermohaline circu-lation in abrupt climate change. Nature, 415: 863-869 (2002). Temperature change expected by 2,050 AD should the present warming trend continue Source:http://www.giss.nasa.gov/data/update/gistemp

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