Saturday, September 21, 2013

Climate Change Workshop, part 3.

And now for something different. Instead of listening to talking heads, no matter how interesting they are, the participants will get on computers and actually work with climatological data, under the guidance of Brad Illston, a research associate at Oklahoma Mesonet, a service provided by the Oklahoma Climatological Survey. This is one of the finest repositories of meteorological information in the country. No other state, as far as I know, has as much data so easily accessible in such a visual format.

Mark Twain referred to "lies, damned lies, and statistics." Statistics can be abused. Brad explained how to use them honestly. But even when used honestly, statistics can be misleading. Averages can be misleading, even if honest. I recall hearing of an old Kansas farmer who said, "In fifty years of farming, I've only seen two average years." So it helps to use not just averages but also some estimate of variability as the standard deviation. If most of the years had been close to average, that Kansas farmer would have seen a small standard deviation. Oklahoma City and San Diego have the same average annual temperature, but the temperatures in OKC are much more variable, a fact constantly confirmed by exchanges of text messages between me and my La Jolla sister.

Another example of being confused by statistics is, what do we mean by a hundred-year flood? It means that, every year, there is a one percent chance of it occurring. It does not mean such floods occur every hundred years, on the dot. As it turns out, the odds of at least one such flood occurring in 100 years is not 100 percent, but 63.4 percent.

The participants then went to the computers to access and use some real Mesonet data. The data are very user-friendly. You can easily graph annual changes in temperature for any year, or for many years on the same graph. Just by looking at the graph, you can see that winter is the season that has the most year-to-year variability (or even day-to-day variability) in Oklahoma. Also, you can access a beautiful color map that indicates soil moisture in August 2011, during a severe drought. Not all of Oklahoma was experiencing a drought; you can see which areas were very dry compared to a long-term average (in red) or wetter than normal (in green). The map is mostly red, but there are green spots. The Oklahoma Mesonet therefore not only makes available a great deal of data in a very organized fashion, but you can construct almost any graph that you might want.

Alek Krautmann works for the Southern Climate Impact Planning Program (SCIPP), which unites meteorological agencies in Oklahoma and Louisiana. Their particular focus is weather disasters. Since 2000, Oklahoma has had 36 federally-declared disasters, the most of any state. Not only are there more weather disaster events now than in the past, but we are becoming more sensitive to them. We have so many more buildings and highways built in hurricane areas, but without any greater mitigation measures, such as building barriers. Not only that, but the way we build our urban and suburban areas can make the disasters worse. We now have so much land paved with concrete and asphalt that the rain that does fall has little chance to penetrate into the ground. In contrast, a forest can help to prevent floods.

A big storm can have a long-term effect on demographic patterns: the 1900 Galveston hurricane may have made Houston the large population hub that it is today. Big weather disasters can have a major impact on ecosystem services, which are the free services that ecosystems provide to us, and which are difficult (but not impossible) to translate into dollars. In addition, the impact of a weather event depends largely on when it occurs. A drought during corn pollination season can cause crop failure even if it is relatively brief. Weather disasters can have numerous indirect effects; for example, droughts cause blue-green bacterial blooms in lakes, which makes the lake water poisonous to come in contact. Major flooding, such as the Mississippi River basin floods of 1993, have a disproportional impact on low-income families who live where the land is cheap, for example on floodplains.

You can monitor drought conditions at a website maintained at the University of Nebraska with funding from federal agencies. You can get past data and the website is updated weekly.

Weather disasters can also test our altruism. If every community along a river builds levees, in an understandable desire to protect their own properties, then there will be a much greater volume of water running downstream, vastly increasing the risk that downstream levees will be overtopped or destroyed.

I would like to end with a book recommendation. The Control of Nature by John McPhee documents three examples of hubris, in which we humans think we can control nature. One of the examples is how we are trying to force the Mississippi River to stay in its present channel, even while we are creating conditions that will ultimately cause it to jump its banks and create a new delta.

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