Projected change in water supply from 2010 to 2040, under business-as-usual climate scenario. Graphic: WRI

By Charles Iceland, Betsy Otto, and Richard Waite
25 July 2016

(WRI) – A changing climate means less rain and lower water supplies in regions where many people live and much of the planet’s food is produced: the mid-latitudes of the Northern and Southern hemispheres, including the U.S. Southwest, southern Europe and parts of the Middle East, southern Africa, Australia and Chile. As WRI-Aqueduct’s future scenarios for water supply show, diminished water supplies will be apparent in these areas by 2020 – less than four years away -- and are expected to grow worse by 2030 and 2040.

Now a new study in the journal Nature provides some of the first evidence that this widely-predicted phenomenon – the movement of clouds and rainfall from the mid-latitudes towards the North and South poles -- is already taking place. Just like the retreat of glaciers and polar sea ice, now clouds and rain are retreating poleward.

Portion of global agricultural production under high or extremely high water stress. Graphic: WRI

This will have huge implications for agricultural production, industrial and energy output, and municipal water provisioning. Many irrigated agricultural areas are already facing water stress. The climate-driven shift of clouds and rain – known as Hadley Cell expansion – will put those areas under even greater stress in the future. Rain-fed agriculture, which many poor people depend upon, will also suffer as a result of reduced rainfall in the mid-latitude regions.

A recent WRI study finds that sub-Saharan Africa will need to more than triple crop production by 2050 in order to feed its growing population. This hard-to-reach target will become more difficult in places like southern Africa and the western Sahel, where water supply is projected to fall.

In addition to worsening water stress and undermining food security, decreasing water supply in the world’s mid-latitudes may also help destabilize nations in these regions, adding to pre-existing political tensions, and helping contribute to armed conflict and migration, as we have seen in places like Syria. [more]

As Clouds Head for the Poles, Time to Prepare for Food and Water Shocks

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