Climate Change and African Rivers

Hydrodependency in Africa: Risky Business
Hydrodependency in Africa: Risky Business

Africa has been deemed “the continent most vulnerable to the impacts of projected climate change” by the UN Intergovernmental Panel on Climate Change. The continent has one of the most volatile water systems on the planet, and its rivers routinely experience wild swings in flow. For example, variation in the Zambezi River is estimated to be ten times higher than that of most European rivers.  This situation will only worsen with climate change.

Despite this hydrological risk, thousands of megawatts of hydropower are being proposed for Africa's rivers (including many of its most volatile and drought-prone). Planning for these dams has not included proper analysis of the risks from natural hydrological variability, much less the medium- and long-term impacts posed by climate change. Africa cannot afford dried-up reservoirs and crippled electricity sectors on top of the already high costs of adapting to a changing climate.

Climate models forecast less rain and higher temperatures across much of Africa over coming decades – and therefore less flow in rivers, and higher evaporation in reservoirs.  An important 2006 report shows that a temperature rise of 3-to-6 degrees Celsius will reduce the water available to Southern Africa by as much as half.  A University of Cape Town climate study says that “it will be like erasing rivers off the map. 

The continent has major renewable energy potential. Yet outside of coal-based South Africa, most sub-Saharan African nations are dangerously over-dependent on hydropower for their grid-based electricity, and many have already suffered drought-induced energy shortfalls. A dryer Africa could also see shrinking forest reserves, and a reduction in fuelwood for cooking (which now accounts for the majority of Africans' energy use). Diversifying away from over-dependence on hydropower is key to increasing the resilience of African economies to climate change.

Adapting to change

As in many parts of the world, millions of Africans rely directly on rivers for their livelihoods.  Large dams will make it harder for them to adapt to climate change.  In a time of growing water stress, dams will reduce water quality and availability for people living downstream.

Dam reservoirs lose large amounts of water through evaporation. More than seven percent of all the freshwater consumed by humans is lost through reservoir evaporation. Sub-Saharan Africa already suffers from the highest water stress in the world, and climate change is making it worse. Big hydropower dams don’t address this problem, and the benefits they do bring are as ephemeral as the rain.

Climate adaptation for Africa’s small farmers requires locally useful projects such as rainwater harvesting, affordable drip irrigation, and other water–saving farming techniques. Such measures reduce poverty at a lower cost. For every billion dollars spent on large dams, five million small farming families could be lifted out of poverty with these kinds of approaches.

More information: 

Climate change and rivers

The Wrong Climate for an African Dam Boom (blog)

Climate Change: Risks to Zambezi Dams (infographic)

Africa's Perfect Storm? World Rivers Review, Aug. 2006

Wrong Climate for Damming Rivers (Google Earth video and fact sheet)

Wilson Center: Climate change, water and conflict in Niger River Basin