A new analysis for the Natural Resources Defense Council (NRDC), examining the effects of global warming on water supply and demand in the contiguous United States, has found that more than 1,100 counties will face higher risks of water shortages by mid-century as the result of global warming.
Not including Alaska and Hawaii, this is more than a third of the counties in the USA.
The analysis by Tetra Tech finds that more than 400 of these counties will face extremely high risks of water shortages. Some states have an extreme or high risk to water sustainability, or are likely to see limitations on water availability as demand exceeds supply by 2050.
These areas include parts of Arizona, Arkansas, California, Colorado, Florida, Idaho, Kansas, Mississippi, Montana, Nebraska, Nevada, New Mexico, Oklahoma and Texas. In particular, in the Great Plains and Southwest United States, water sustainability is at extreme risk, says the report.
While water management and climate change adaptation plans will be essential to lessen the impacts, they cannot be expected to counter the effects of a warming climate, the report warns. One reason is that the changes may simply outrun the potential for alternatives such as modifying withdrawals, increasing water use efficiency, increased water recycling, enhancing groundwater recharge, rainwater harvesting and inter-basin or inter-county transfers to make up for water deficits.
The widespread nature of the risk of water shortages may also limit the effectiveness of local solutions – such as acquiring more water from a neighboring county or basin – since many other localities will be trying to get control of the same resource.
Water withdrawal will grow by 25% in many areas of the US including the arid Arizona/New Mexico area, the populated areas in the South Atlantic region, Florida, the Mississippi River basin, and Washington DC and surrounding regions.