Temperatures in the Coastal Bend: Changing odds
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Clear skies, high pressures, it is hot; last week 106 degrees F on Monday, 108 degrees F Tuesday, over 100 degrees F four days in a row, and the forecast, for more of the same. May was hot, 4 degrees F above average for us, 6 degrees F high for most of Oklahoma and 8 degrees F high for most of the area from Kansas to New York. More than 2,000 new record high temperatures for the week. Is it global climate change, considering a record heat wave last summer in Texas/Oklahoma and similar trends in East Europe/West Asia in 2010?
What is going on?
Dr. James Hansen climate scientist at NASA/Columbia University says that looking at those kinds of anomalies (differences between current climate and historical averages) is a bad way to understand long-term climate patterns. There is too much variability in weather to "see" patterns looking at individual extreme events. He and others suggest that it's better for the public to look at general trends in the odds of having above-average or below-average temperatures, using so called "climate dice." If the dice are fair (no change in climate) then the odds of being warmer or colder would stay the same year to year. If the odds of higher-temperature events go up then the climate is changing. Using years of worldwide climate data they're answering the question, "Are current climate dice fair?"
Historical climate dice are not accurate
Looking at land temperatures and ocean temperatures for 2006-11, the facts are: anywhere from 4-13 percent of the globe experienced extreme high temperatures when fair dice would predict only .01-.02 percent of the globe experienced such extremes. Think of it this way. Globally, if you use a six-sided die to forecast weather anomalies, four sides are now red, forecasting hotter summers, one is neutral and one is blue (cooler). For North America it is even worse. Odds are 80 percent red, because land temperatures are more variable than the ocean. Really extreme events like ours in 2011, Russia in 2010, and France's heat wave of 2003 are now 10 times more likely than in the 1950s. And winter trends are following a similar pattern, but it is less obvious because of winter weathers greater variability. Hansen points out more extreme snow events occurring are not indications of extreme low temperatures as some would suggest. Where it is cold enough to snow there will be more snow because warmer air can hold more moisture.
What are the conclusions from all these studies?
Weather in the Coastal Bend will, on average, be hotter in the future; spring will come sooner; fall later; winters will be shorter. With more atmospheric water, extreme rain events will be more common in the northern hemisphere: more 100-year and 500-year floods. Cool-year odds will drop from 1 in 3 to 1 in 10. World temperatures will rise at least 1 degrees F. But, a new problem will be odds of really extreme heat over land. They have increased markedly; temperature extremes similar to those now occurring in the Midwest are increasing likely. Those odds used to be infinitesimal. Now over 10 percent of the earth's temperate land mass will encounter extreme heat anomalies in a given year.
These predictions are conservative. Respected climatologists agree added amounts of carbon dioxide accumulating in the atmosphere from burning fossil fuels will increase temperatures by closer to 2 percent instead of the recently observed 1 percent. Then things only get worse. Hansen's and others concern, can we adapt; can plant and animal life evolve (adapt) fast enough to the new dice to survive?
Public Perception of Climate Change and the New Climate Dice, Proceedings of the National Academy of Sciences, James Hansen et al., 2012
National Weather Service, Climate Prediction Center
NOAA. State of the Climate Global Analysis, May 2012
Intergovernmental Panel on Climate Change (IPCC), 2007: Climate Change: The Physical Science Basis, Susan Solomon et al. eds, 2007
Increase of extreme events in a warming world, Proceedings of the National Academy of Sciences, Rahmsdorf, S and Coumou, D, 2011
Ecological and evolutionary responses to recent climate change, Annual Review of Ecology, Evolution, and Systematics, Camille Parmesan, 2006
Mary and Paul Meredith, both native Texans, are retired university professors living in Victoria since 2003. They are trained naturalists and conservationists concerned about ecological issues facing Coastal Bend residents. They are active in various conservation organizations in the region.