Fresh warnings about the prospects for mega-drought in the American southwest.
20, 30, 50 year droughts? Factor that into America's desert cities where water is already scarce.
There's a lot that can be done - conservation, recycling of waste water, the development of drought-resistant crops - a lot, yes, but not enough. Surface water is already in decline and ground water, aquifers, are being drained fairly rapidly.
One thing that's becoming a near certainty is that water is going to become very, very expensive in the southwest and that cost will reshape demographics. People and businesses will have to decide whether to stay, and absorb the water cost penalty, or relocate to escape the drought. An exodus would be chaotic and disruptive for those leaving and for those remaining behind.
Where has the water gone? Well it's in the air, up in the atmosphere. A warming atmosphere acts like a sponge to absorb water vapour. The warmer the atmosphere the more water vapour will be lost through evaporation and transpiration. That warmer, wetter atmosphere fuels more intense, severe storm events and phenomenon such as "atmospheric rivers." An example of this is the Pineapple Express that has been lashing the west coast from San Francisco northward over the past month. c
We know what's coming. Mass migration out of the south for which the Pacific Northwest will be Ground Zero. Fortunately I'll not be around to see it. For my kids, it could be a different matter.
