Wednesday, July 11, 2007

Climate Change, Water, Food and Fuel

Few of the reports I've seen about the current heat wave and drought in the West explicitly mention a connection to climate change. After all, climate is what we expect, weather is what we get, and the two often seem disconnected from each other. But in this case, they are linked in at least the following way: current conditions out West exemplify what climate scientists have been telling us to expect more frequently, as the earth warms. It's hard to look at the situation and not see numerous feedback loops with significant potential consequences for the growing population of the Sunbelt, and for the entire economy. Sustained dry conditions in the Western US could jeopardize food supplies and amplify the mechanisms of global warming.

Having spent much of my life in California, I'm conscious of the way that water and development have always been tied together in the West. Los Angeles only grew to its present scale because of the contracts and infrastructure that bring water from the eastern Sierra Nevada and the Colorado River to SoCal. In the semi-arid southwest, residential and agricultural demand for water have historically been in tension with conservation interests, and the balance among them has gradually shifted towards the latter in the last few decades. If climate change yields a significantly drier pattern in the West than what has prevailed for the last fifty years, then the entire system will be stressed. Given the migration rate into the region, with metro areas like Las Vegas and Phoenix growing at multiples of the national rate, it's hard to see residential water use ending up as the lowest priority use of scarce water. Homeowners and businesses can outbid farmers, and the agricultural bounty of places like the central valley of California, which depends heavily on irrigation, could be at risk.

But just as climate change can influence these conditions, the reverse is also true, via the basic mechanisms of climate change. The drier the West becomes, the less vegetation it can support. That reduces the region's natural uptake of CO2, which helps to mitigate the impact of man-made emissions. But it also creates the conditions for putting large quantities of stored carbon back into the air, via the wildfires that become more frequent and extensive during a severe drought. That could ultimately force us to make even deeper cuts in the greenhouse gases emissions from transportation and industry, in order to stabilize the concentration of these gases in the atmosphere. The climate neither knows nor cares whether a ton of CO2 came from a car's exhaust, from a coal power plant, or from a forest fire. The global effect is exactly the same.

Now throw biofuels into the mix. While they represent an important strategy for reducing our use of the fossil fuels that contribute to climate change, their cultivation under drought conditions adds to the competition for water among food crops, natural systems, and the increasing demand from development. In this context, food vs. fuel becomes a subset of a larger fight over water, fed by climate change but affecting climate change in turn. Compared to this, the geopolitics of oil are simple.

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