By now, we know of the effects of climate change on the world's oceans. But it appears to be heating up the world's lakes even faster than both the oceans and the atmosphere, according to a new study.
Researchers used satellite and ground data to measure temperatures in 235 lakes spread over six continents, between 1985 and 2009, for the comprehensive global study funded by National Aeronautics and Space Administration (NASA) and the National Science Foundation.
The results were alarming: Lakes are warming an average of 0.61 degrees Fahrenheit every decade, compared to about 0.13 degrees Fahrenheit per decade for the earth's sea surfaces. Lake warming is even more pronounced at higher latitudes, reaching 1.3 degrees Fahrenheit per decade, according to a study published Wednesday in the journal Geophysical Research Letters.
While it may not sound like much, it's enough to do serious damage, as The Christian Science Monitor pointed out. Warming lakes can cause harmful algal blooms, which inhibit plant and animal life, to grow. They can increase methane emissions, a harmful greenhouse gas. Most immediately, however, warming lakes can threaten a major source of drinking water, energy production, irrigation, and food for populations across the globe.
Why are the earth's lakes heating up so fast? Scientists point to a number of factors.
As global air temperatures rise, so too do the temperatures of earth's lakes. Since 1880, Earth’s average surface temperature has warmed by about 1.4 degrees Fahrenheit, according to the National Oceanic and Atmospheric Administration (NOAA). Most of that warming has occurred in the last three decades and appears to be driven by greenhouse gas emissions, according to NOAA.
Less cloud cover is also to blame. Clearer skies allow more solar radiation to penetrate lakes' waters, exposing them to more of the sun's warming rays.
And in northern climates, lakes are losing their ice cover earlier in the spring, leaving them more susceptible to warming. That's because ice is usually a good insulator against atmospheric heating. Without it, bodies of water are more exposed to warm air and the sun's rays, causing them to heat up faster.
While the world's lakes are already heating up and some change is inevitable, there are ways we can slow the warming.
"Our climate is changing because humans are adding large amounts of heat-trapping gases to the atmosphere," the Union of Concerned Scientists (UCS), a non-profit science advocacy organization, said in a recent report on climate change solutions. "The good news is that practical solutions exist today to address this growing problem."
In one area the Union studied, the majority of heat-trapping emissions came from utility and industrial energy use, as well as vehicles and waste.
In order to tackle the problem, the group suggested ways to reduce emissions from industry, business, and homes, as well as landfills and agriculture.
It suggested updating electricity efficiency standards, providing incentives for clean energy use, increasing fuel efficiency standards for cars, addressing methane from livestock, and improving soil management to reduce emissions from agriculture.
For example, nitrous oxide emissions, primarily from the breakdown of nitrogen fertilizers, make up 64 percent of agricultural emissions. Methane is the next largest source at 34 percent. US Environmental Protection Agency programs that reduce methane from livestock and the use of nitrogen fertilizers decrease emissions as well as improving drinking water, lakes, and wetlands, according to the UCS.
Perhaps most importantly, however, scientists can prepare ways to cope with the inevitable changes, such as algal blooms and habitat change, that lake warming will affect, adds the group.
"Because some warming is inevitable," it says, "we must also anticipate and plan for the unavoidable impacts of change through long-term management strategies."