Climate Feedback and Global Warming

Climatology is meteorology writ large. They are really different branches of atmospheric science. If you want to know whether it is likely to rain tomorrow talk to the weatherman who is a meteorologist. But if you want to know about what the weather will be like in a number of years, you should consult a climatologist.

A considerable irony concerning our recent heat wave in the area, think meteorology , is the use of air conditioning to combat the heat. Using air conditioning requires power to generate the necessary electricity. The electricity comes to a large degree from burning fossil fuels which contribute to global warming, think climatology. This short term reaction to a meteorologic phenomena contributes to a long term climatological phenomena. Climate scientists call this positive feedback. Burning fossil fuels to run air conditioners contributes carbon dioxide to atmosphere which traps heat and makes the planet warmer, which requires more air conditioning, which causes carbon dioxide release which causes more heating which… You get the picture.

In this case the feedback has a human element. Other feedback loops are purely physical phenomena. These feedback loops add to the complexity of climate modeling. Predictions of future climate rely on computer calculations, the accuracy of which depend on how well the variables in a climate system are understood.

Water vapor in the atmosphere is without question the most important of the global warming feedback loops. Water vapor is a strong greenhouse gas itself; that is, its presence in the atmosphere traps heat and contributes to global warming. The positive feedback comes about because the amount of water vapor in the atmosphere is directly proportional to the temperature of the atmosphere. The hotter the atmosphere the more water vapor, the more water vapor in the atmosphere, the more heat trapped in the atmosphere, the more water vapor in the atmosphere, the more… You get the picture.

When natural gas (methane) is burned it produces carbon dioxide, a major greenhouse gas. Unburned methane released to the atmosphere is itself a potent greenhouse gas. There are vast stores of methane trapped in permafrost of the tundra. As the planet warms, the permafrost thaws which releases methane. Methane release warms the planet thawing more permafrost which releases more methane which… You get the picture.

The amount of solar heating of the planet is a function of albedo, the reflectivity of the planet. Sunlight is strongly reflected by snow covered expanses near the north and south poles. As the climate warms due to global warming, the snow melts exposing soil which is much less reflective. The less reflective soil traps more heat, warming the planet further, melting more snow, which traps more heat… You get the picture. The same is true of sea ice and the oceans. Ice is more reflective than water.

A final irony is that as the area of the oceans covered with ice shrinks, it opens more area to exploration and untimely production of crude oil, but you get the picture.

Originally published in the Russellville courier, July8, 2012

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  1. Pingback: Impermanent Permafrost - Bob of the Ozarks

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