Warmer temps and nutrients could increase lake methane emissions

According to a new study, shallow lakes and ponds are potential hotspots for increased methane emissions that could contribute to global warming.

Shallow waters contain pockets of methane, typically absorbed by the plants in the water’s ecosystem. However, as lakes warm and more plants die off, the trapped pockets of methane will bubble up in a process called ebullition.

Methane has 25 times the global warming potential of carbon dioxide, so as more methane bubbles up and is emitted into the atmosphere, the greater the greenhouse effect will be.

The new study, conducted by researchers from Aarhus University in Denmark, describes the “synergistic” relationship between methane bubbles in lakes, warming temperatures, and eutrophication.

Eutrophication occurs when a large number of nutrients, often from fertilizer runoff, enrich bodies of water and increase phytoplankton while starving out other plants.

The results of the study show how important it is to implement strategies to mitigate methane emissions from shallow waters.

The researchers used a mesocosm experiment to examine the impact that warming and eutrophication would have on methane bubbling. A mesocosm is any controlled outdoor experiment that studies how climate and other conditions affect water and natural environments.

Both an increase in nutrients and warming temperatures were found to be the main drivers of methane bubbling and methane emissions.

The researchers also found that warming temperatures alone increased methane emissions by 50 percent in shallow lakes, but combined with eutrophication, emissions rose to 95 percent.

Plants had a significant effect on keeping methane emissions in check, which was canceled out by the biodiversity loss that happens with eutrophication.

The study shows how vital plants are in mitigating methane emissions in lakes and ponds, and the research could help pave the way for management strategies that reduce nutrient runoff from fertilizer to keep biodiversity intact.

—

By Kay Vandette, Earth.com Staff Writer

Image Credit: Ben Goldsmith