Fresh Water Supplies in Danger Due to Warming Conditions

Study finds world’s lakes are warming at an even faster rate than the oceans.

The fresh water supplies in lakes across the globe are becoming endangered due to climate change and rapid warming, according to a new study announced at the American Geophysical Union meeting. The findings of the study, funded by NASA and the National Science Foundation and cited on eurekalert.org, found that lakes are warming an average 0.61 degrees F every 10 years, and faster than the warming rate of the ocean or the atmosphere.

The study involved 235 lakes, over half of the freshwater supply of the world, and used satellite and ground measurements recorded over 25 years to make the determinations, and is the largest study of its kind. The researchers used satellite measurements to take surface temperatures of the water, and hand instruments, which go back for more than 100 years, to monitor the temperatures throughout the lakes.

Simon Hook, science division manager at NASA’s Jet Propulsion Laboratory said the combination of satellite and ground temperature measurements provided the most comprehensive view of how the lake temperatures are changing across the world.

The issue at hand is the warming water is causing algae to bloom at increased rates, and projections say the increase could be 20 percent over the next 100 years.  The research team also predicted that algae that is toxic to fish will increase by five percent as well over the same period.

Algae blooms also rob the oxygen from the water, endangering fish, a primary source of protein for many people living near the lakes around the world, as well as the livelihoods of many.

The findings also suggest if current conditions continue, emissions of methane gas will increase 4 percent in the next decade.  Methane is a greenhouse gas that is 25 times more powerful on 100-year time scales than carbon dioxide.

The lead author of the study, Catherine O’Reilly said the findings suggest larges changes in our lakes are not only unavoidable, but are probably already happening, and her earlier research has shown lake productivity declining in lakes that have rising temperatures.

Study co-author Stephanie Hampton added society depended on surface water, not just for drinking water, but for energy production, crop irrigation and manufacturing.

Warm water lakes, like those in tropical areas, seem to be seeing a less dramatic shift than cold water lakes, but Hampton says we should not dismiss the lower rates of change as harmless, noting they can be just as important as a higher change in a cooler lake.

The researchers said “The pervasive and rapid warming observed here signals the urgent need to incorporate climate impacts into vulnerability assessments and adaptation efforts for lakes.”

The findings of the study were published in Geophysical Research Letters, as well as being announced at the meeting.

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