With all the flooding in the Midwest (and the persistent drought elsewhere) researchers are reminding us their could be a link between a warmer world and precipitation patterns.
This year’s remarkable floods could well be just as rare, but normal, as the great Midwestern floods of 1993. But it is clear to climatologists that the conditions driving this year’s rising waters — periods of heavy rain — are more likely in a warming world because warmer air holds more water vapor. Kevin Trenberth, a longtime contributor to the reports of the Intergovernmental Panel on Climate Change and an expert at the National Center for Atmospheric Research, explained things a bit this morning in a couple of e-mails.Weathermen have often mentioned the feedback loop from saturated ground where as it dries it simply reloads the atmosphere above it for the next deluge. Meteorologist Cindi Clawson brought up another good point this week on US Farm Report: saturated ground keeps the temperatures cooler as it dries, so crop development will likely also be retarded by temperatures as well as moisture.
He cited a recent analysis by scientists from the National Climatic Data Center that confirmed earlier studies showing a substantial increase already in the intensity of precipitation across the United States, interspersed by longer dry spells.
“The greater intensity comes mostly from the increased water vapor in the atmosphere: overall up about 4 percent since 1970, a bit less over land and dry regions,” Dr. Trenberth wrote. “The general rule of thumb on this is that ‘the rich get richer and the poor get poorer’ — i.e., the wet areas are apt to get wetter and dry areas drier. This assumes that the main atmospheric circulation patterns don’t change much (or is second order, as seems to be the case) and so the moisture that is evaporated into atmosphere and is lying around gets transported to where it already rains and away from the areas where it doesn’t.” [More]
The ground-truth (heh) for me is I finally got some payoff on expensive drainage system tiles I have installed over the last decade (although now I just as soon have not). Of course, it helps me get in the field earlier in spring and aids at harvest, but getting water off a field in 24 hours can mean the difference between a crop and none.
If we do see a climate trend that pumps more water into particular areas each season, soils like mine will experience an increasing benefit from drainage upgrades. In fact, it could be an even bigger factor in land prices, with drainage system maps and data touted more than soil maps and yields.
The bummer: tile is, of course, drived from petroleum and guess where prices are going?