Thursday, July 29, 2010

Climate Change Impacts Water Supply

From the Planning and Conservation League, a notice of a new report on anticipated future water supplies and solutions.

A new report by the consulting firm Tetra Tech reveals the impact climate change will have on water supply reliability in the United States and clearly demonstrates that urgent action is needed to move California toward more sustainable water supplies. You'll note in the chart from their report above (click to enlarge) that the water issues in Southern California are in extreme risk to water sustainability conditions under climate change.

As part of its analysis, Tetra Tech used an index to assess risks to water supply reliability on a county-by-county basis. Fully one-third of all counties in the lower 48 states will face high risks of water shortage by 2050, and nearly half of those will face extremely high risks of water shortage. Water use in some of these high-risk areas like the Great Plains and the Southwest is already unsustainable. As climate change affects temperature and precipitation levels, the number of counties facing high water shortage risks will increase, and areas like the Great Plains and the Southwest may not have any available precipitation at all.

Higher temperatures mean less water for two principal reasons. First, a changing climate means shifts in precipitation, including a change in how much, where, and when rain falls. In California, we are likely to see more rain and less snow, for example. Second, warmer temperatures cause an increase in evaporation both from ground surfaces like lakes and reservoirs and through vegetation.

In the report Tetra Tech took into account an increase in water demand over the coming decades, estimating that total water demand in the United States may grow as much as 12.3% by 2050. Their analysis shows that climate change will have a significant effect on future water supplies, particularly in places like California that already contends with shortages. The Tetra Tech report can be downloaded here.

The PCL has produced a paper on solutions to the water issues that address these problems in a new way, particularly with respect to the damage that a peripheral canal solution would have on the entire Bay Delta region. Their solution consists of a much smaller tunnel instead of a canal, and a series of projects that restore the hydraulic functioning of the Bay Delta and preserve the fish populations that have collapsed recently. That report can be downloaded here.

There has been a long discussion by many parties across the state regarding the problem solutions to the Bay Delta. The whole dialogue seems to finally be coming around to the necessity of restoring the natural processes and conserving water wherever possible, and implementing reclaimed water strategies in order to replenish local aquifers and rivers. The next order of business is to manage growth and change its form to accommodate the realities of the future that's rapidly descending upon us. Which means changing the whole "growth" mantra into a sustainable economic model as well.