Rivers Shrinking Worldwide

Photo via Jaymi Heimbuch

The US National Center for Atmospheric Research (NCAR) is releasing a study showing that major rivers worldwide are drying up due to climate change. The study further shows that approximately one-third of the world’s major and most vital rivers have suffered significant changes over the last half century including the Ganges, the Niger and the Colorado.

The comprehensive study assessed 925 rivers using both satellite data and on-the-ground measurements. They found that while changing rainfall patterns, glacial melt water; and, other causes increased the flow in some rivers; the majority of rivers had lost water. The researchers are singling out global warming as the major contributing factor to the world’s major rivers drying up.

This map shows the change in runoff inferred from streamflow records worldwide between 1948 and 2004, with bluish colors indicating more streamflow and reddish colors less. In many heavily populated regions in the tropics and midlatitudes, rivers are discharging reduced amounts into the oceans. In parts of the United States and Europe, however, there is an upward trend in runoff. The white land areas indicate inland-draining basins or regions for which there are insufficient data to determine the runoff trends. (Graphic courtesy Journal of Climate, modified by UCAR.)

Still, it is not altogether fair to put all the blame on global warming as climate change is not the only thing endangering our water systems. Humans have built dams, levees, dykes and other structures that alter the flow; divert the natural flow of rivers to send the water elsewhere; drained rivers for agricultural purposes; and, the list goes on.

However, it certainly plays a significant role, as shown in this study. Quote from businessGreen.com:

Overall, the study found that from 1948 to 2004, annual freshwater discharge into the Pacific Ocean fell by about six per cent, or 526 cubic kilometres – approximately the same volume of water that flows out of the Mississippi river each year. Similarly, the annual flow into the Indian Ocean dropped by about three per cent, while the flow of the Columbia river in the US declined by about 14 per cent.

In contrast, annual river discharge into the Arctic Ocean rose about 10 per cent, primarily as a result of higher temperatures leading to increased levels of glacial melt water.

"Reduced runoff is increasing the pressure on freshwater resources in much of the world, especially with more demand for water as populations increase," said Aiguo Dai, a scientist at the NCAR and lead author of the report. "Freshwater being a vital resource, the downward trends are a great concern."

The study comes on the heels of the warning by the officials in Australia that parts of the Murray River have fallen so low that Adelaide could run out of water within two years. Regions globally facing the greatest threats now include those dependent on the Niger in West Africa; the Ganges in South Asia; the Yellow river in China; while large areas of the western US could be impacted by the reduced flow of the Colorado river.

In related news, Oxfam International released a report this week warning that aid agencies could be overwhelmed within seven years as a result of the increased incidence of climate change-related disasters.

The study showed that the number of people impacted by extreme weather events has doubled within 30 years and is likely to increase by a further 54 per cent by 2015, based on the latest climatic predictions.

The report concludes that global emergency spending will have to be nearly doubled to $25bn (£17.2bn) a year. Other required help would include funding developing nations be provided with significantly increased funding to allow them to take advantage of climate change adaptation measures. Further, it went on to state that any UN climate change negotiations include that rich countries deliver a medium-term commitment to spend $42 bn a year to help poorer countries with climate change adaptations. It also states that the spending be increased to $50bn (£25bn)a year in the near future.

The results will be published May 15 in the American Meteorological Society's Journal of Climate. The research was supported by the National Science Foundation, NCAR's sponsor.