Rivers Drying Up as Climate Change Takes Hold

New data issued on April 21st highlighted the effect that climate change is having on many of the world’s most significant rivers.  Among those covered were the Ganges, China’s Yellow River, the Colorado and the Niger – all of which lie within highly populated areas.

Combined with practices like irrigation and damming, the drying-up process that is taking place as climate change takes hold could put future generations’ water and food supplies at risk, the scientists behind the report wrote in the current edition of the Journal of Climate, which is produced by the American Meteorological Society.

"Reduced runoff is increasing the pressure on freshwater resources in much of the world, especially with more demand for water as population increases”, head researcher Aiguo Dai, stated, adding: "Freshwater being a vital resource, the downward trends are a great concern."

River Water Flow Levels

Dai and his colleagues from Colorado’s National Center for Atmospheric Research analysed historical data relating to over 900 river water flow levels around the world.  In almost 300 instances, they found that substantial changes had taken place. 

Between 1948 and 2004, they said, the amount of freshwater flowing into the Pacific Ocean each year had dropped by 526 cubic kilometres – equivalent to around a six per cent loss. 

Freshwater flow into the Indian Ocean, meanwhile, was down 140 cubic kilometres – a three per cent loss.

In the US, lower levels of rainfall and greater water consumption conspired to lower the Columbia River’s water volume by approximately 14 per cent.

While drawing attention to how human activities had impacted on water flow, the researchers detailed the ramifications of climate change too, describing how temperature rises were causing rainfall trends to change, as well as causing evaporation to take place more frequently.

The sole area where water flow had actually increased was the Arctic, but here, ice melts were the cause.

"Also, there is evidence that the rapid warming since the 1970s has caused an earlier onset of spring that induces earlier snowmelt and associated peak streamflow in the western United States and New England and earlier breakup of river-ice in Russian Arctic rivers and many Canadian rivers”, the report asserted.

Hinting at the future, report author Kevin Trenberth added: “As climate change inevitably continues in coming decades, we are likely to see greater impacts on many rivers and water resources that society has come to rely on.”

While the report focused on rivers, Environmental News recently looked at the state of Lake Mead, where the water level has dropped intensely in recent years.