What We Know About Climate Change (Boston Review Books) by Emanuel Kerry

Author:Emanuel, Kerry [Emanuel, Kerry]
Language: eng
Format: epub
ISBN: 9780262305143
Publisher: MIT Press
Published: 2012-10-25T22:00:00+00:00

This exercise has been repeated using many different climate models, with the same qualitative result: one cannot accurately simulate the evolution of the climate over the last 30 years without accounting for the human input of sulfate aerosols and greenhouse gases. This is one (but by no means the only) important reason that almost all climate scientists today believe that man’s influence on climate has emerged from the background noise of natural variability.

5

The consequences

Projections based on climate models suggest that the globe will continue to warm another 3–7°F over the next century. This is similar to the temperature change one could experience by moving, say, from Boston to Philadelphia. The warming of already hot regions—the tropics—is expected to be somewhat less than the global average warming, while the warming of cold regions like the arctic is projected to be more, a signal already discernible in global temperature measurements. Nighttime temperatures are increasing more rapidly than daytime temperatures, and the temperature over continents is increasing faster than that over the oceans.

Is this really so bad? With all the negative publicity about global warming, it is easy to overlook the benefits: it will take less energy to heat buildings, previously infertile lands of high latitudes may start producing crops, and there will be less suffering from debilitating cold snaps. Increased CO2 should also make some crops grow faster. On the down side, there will be more frequent and more intense heat waves, air conditioning costs will rise, previously fertile areas in the subtropics may become barren, and blights may seriously affect both natural vegetation and crops.

So there will be winners and losers, but will the world really suffer in the net? Even if the changes we are bringing about are larger than the globe has experienced in the last few thousand years, they are smaller than the big natural swings between ice ages and interglacial periods, which the earth and indeed human beings survived.

The difference now, in a nutshell, is civilization, which developed during a period of exceptional climatic stability over the last 7,000 years. While our distant ancestors had to cope with a sea level rise of about 300 feet over a mere 8,000 years or so leading up to the development of civilization, human society has since become finely adapted to the current climate, so much so that a mere three-foot increase in sea level (small by the standards of geologically recent changes) would displace around 100 million people. Agriculture and animal husbandry are also tuned the present climate, so that comparatively small shifts in precipitation and temperature can exert considerable pressure on government and social systems whose failures to respond could lead to famine, disease, mass emigrations, and political instability.

Sea level rise is among the most serious potential consequences of global warming. During the peak of the last ice age, sea level was some 400 feet lower than today’s, since huge quantities of water were locked up in the great continental ice sheets. Today, almost all land ice is contained in the Greenland and Antarctic ice sheets.

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