The primary threat to the flow of the Nile with a warming planet is water loss, though not necessarily due to decreasing rain. General circulation models (GCMs) used in climate prediction have shown—and been proven right by the last three decades of data—that global warming, while increasing the overall heat content of the atmosphere and ocean, will tend to exacerbate local conditions, particularly with respect to water: dry areas will become drier, and wet areas will become wetter, even as temperature rises (unevenly) around the world.
Nile flow rates.
In eastern Africa, particularly in the mountains of Ethiopia, rainfall is predicted to become more variable from year to year, with periods of extreme rainfall followed by increasingly severe droughts. Though the net decadal rainfall might be the same or slightly greater than now, the unpredictable and changing nature of rainfall and river flow will destabilize the ecosystems and societies which depend on the Nile.
Course of the Nile, with Grand Ethiopian Dam.
The main stress is due to come from human consumption, in Egypt, Sudan and Ethiopia. Populations in that region of Africa are predicted to double in the coming fifty years, so demands on the river’s fresh water supply will only increase. Infrastructure will pose a problem too, as Ethiopia is in the process of building the Grand Ethiopian Renaissance Dam, proposed to provide 6 GW of electricity to the country’s growing population. The reservoir is expected to take from 5-15 years to fill. Meanwhile Egyptian officials have threatened military action to prevent the dam’s completion. The upper Nile threatens to be a focus for the increasingly looming water wars in the arid regions of the planet, as population rise and warming, increasingly hard-to-predict weather increase the pressure on national governments to act for their citizens’ welfare.
Grand Ethiopian Renaissance Dam.
Tomorrow: Egypt and climate change.
Be brave, and be well.
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