Jan 30, 2013

Drought, doom, and the data* #water #green #greatlakes

2012 was seriously hot and dry- the warmest year on record in the United States and the country had the worse drought in over half a century, with 80 percent of our agricultural land experiencing drought. Climate scientists predict that climate change could be creating more droughts- through warmer temperatures and changing precipitation patterns.

The USDA reports that we’ll see the impacts of the 2012 drought at the grocery store this year- with expected increases of 4% in prices for meat and milk. They estimate that the nation’s corn crop was down more than 10% from the previous year, raising prices. Because corn provides the the foundation of the feed for livestock, the price increase plays out for consumers at the butcher counter or dairy case.

Whenever people start discussing the potential impacts of climate change on agricultural production, it’s common to hear that the plants will be able to adjust. After all, isn’t that the basic story of natural selection? The genetic diversity of a species allows it to adapt to changing environmental conditions- the fittest in the new regime survive and prosper, producing more well-adapted offspring. Last week, a paper published in Nature titled “Ecosystem resilience despite large-scale altered hydroclimatic conditions,” sounded pretty optimistic, from the title at least, on the ability of plants to adapt to drier climes. They used data from a network of long-term ecological research sites in the U.S. and in Australia to compare vegetation productivity from the past decade of hotter, drier conditions to earlier, wetter decades.

They used the vegetation productivity, precipitation data and evapotranspiration estimates to determine the water use efficiency of the vegetation. Across ecosystems, they found that plants used more water when it was available, but shifted to higher water efficiency during drought conditions. That sounds like good news for plants in an era of climate chaos, but the authors also found that the water-use flexibility, also referred to as resilience, can be pushed past a breaking point.

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