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Natural scientists by nature are cautious; their theories and predictions are always subject to questioning and revision as new facts, and new ways of looking at the old facts, surface. This is particularly true for very complex systems, such as Earth’s climate, where there are many variables and myriad uncharted interactions among those variables. The weather lady can’t describe exactly what a city’s weather will be next month, though meteorologists can give the likelihood of precipitation and a probable temperature range. The future is uncertain, but there is a huge amount of scientific data available about what makes the world’s climate work and where it may be going. I’m not a scientist who could be embarrassed by predictions which go beyond undisputed facts, so I step out and sketch where you should live twenty years from now based on foreseeable climate change.
A few basics: Much of climate is determined by “Hadley cells.” The ocean receives the most heat when the sun is directly overhead, and it releases much of that heat through water evaporation. The moist tropical air goes up because the northern hemisphere and southern hemisphere trade winds crash into each other near the Equator and push air straight up. The moist air cools as it goes higher, and the cooling causes rain to fall on the ocean and on tropical jungles such as the Amazon. After the tropical rains, the dried-out air flows towards the poles in high-altitude streams which continue until the air cools enough to drop down and begin its journey back towards the Equator. In sum, a northern Hadley cell is a long air flow loop which dumps massive rains on the tropics and then continues north to create deserts, such as the Sahara, in those places where the cell’s dry air drops to the ground.
Earth’s climate is unequivocally heating – see my August 6th post “Science as Truth-Seeking” summarizing conclusions of the “Berkeley Earth Surface Temperature” project. Hotter air will make the northern Hadley cell loops longer, and the dry air, some of which now desiccates Mexican deserts, will be dumped further north in the already-dry American West. Global warming will raise temperatures all over the country, but the West will receive a double hit of less precipitation and speedier loss of moisture because of heat. The United States west of a line between Chicago and Houston will, I predict, become drier as well as hotter. The East will become hotter than it is now, but also wetter because of proximity to oceans. Dry Hadley cell air flows in a southeasterly direction back towards the Equator, and some of that dry air will evaporate water from the Atlantic Ocean and release it when it hits the East Coast. So more heat and a northward-displaced Hadley cell will increase precipitation east of the Chicago-Houston line.
We know that hotter air and sea water will generate more powerful storms, floods and rising seas. Living near the ocean, particularly in low-lying areas like Florida and much of the Gulf Coast will be increasingly dangerous to life and property. On the other hand, the 100-mile-wide strip along the Pacific from San Francisco up to the Canadian border should continue to be watered and cooled by winds off the Pacific and by ocean currents, so that strip is high on my list of desirable real estate. Temperatures tend to drop and precipitation to increase with higher altitudes, so living in a mountain town may also be a good move. The lowest point in the country, Death Valley, is definitely not recommended. These prediction are guided by the predictions and evidence William deBuys presents in “A Great Aridness.”
So my general projection for 2032 is that it will be better to live East rather than West, North rather than South, higher rather than lower, and not real close to big bodies of water.