Monday, May 01, 2017

Climate Change Will Alter Flow of River Nile

The 400 million people who depend on the predictability of the River Nile face an uncertain future as global warming delivers more extreme weather.

Displaced people collecting water on the banks of the River Nile, Awerial County, South Sudan. (Image Credit: Geoff Pugh/Oxfam East Africa via Flickr) Click to Enlarge.
A 5,000-year-old problem is about to get much more problematic.  Climate change will make it harder than ever to bank on the flow and annual flood of the River Nile.

The Nile is the natural world’s great gift to human history:  its annual flood delivered nourishing silt and vital water for the farmers who supported a hierarchy that founded a civilization.
Need for the Nile
And the Nile now matters more than ever:  400 million people in 11 countries depend on the flow in the Nile basin.  Many of them already live at water scarcity levels of below 1,000 cubic meters of water per person per year.

By 2050, the population of the Nile basin will double, and start heading towards a billion.  So people need the river more than ever.

But, according to a new study, the Nile is about to become more unpredictable.  Climate change, as a consequence of global warming driven by carbon dioxide build-up in the atmosphere, itself a consequence of ever more prodigal combustion of fossil fuels, will overall mean that more rain will fall and flow down the water courses that feed the Nile system.

But the same computer simulations, reported in Nature Climate Change, also predict that under the notorious “business as usual scenario” in which humans go on exploiting fossil fuels, there will be substantially fewer “normal” years, with flows of between 70 and 100 cubic kilometers of water per year, and more years of either devastating flood or withering drought.

The Nile flow is affected by the cycle of Pacific temperature oscillations:  2015 was an intense El Niño year, which saw a drought in Egypt.  The same oscillation’s obverse, La Niña in 2016, was linked to high flooding.

“It’s not abstract.  This is happening now,” says Elfatih Eltahir, a civil and environmental engineer at the Massachusetts Institute of Technology in the US, and one of the researchers. “We think climate change is pointing to the need for more storage capacity in the future.”

Read more at Climate Change Will Alter Flow of River Nile

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