Scientists have discovered that methane discharge from freshwater lakes could double over the next 50 years because of a feedback loop. Further, debris from plants located in reed beds causes the emission of the gas.
A feedback loop is something that accelerates or decelerates a warming trend. Positive feedback accelerates a temperature rise, whereas negative feedback decelerates it.
Because of climate change, the number of cattail plants growing around the lakes is increasing. Despite this, debris from reed beds aggravates the discharge of methane. Methane gas is about 25 times more warming than carbon dioxide found in the atmosphere.
Freshwater lakes are essential to the environment, but it is relatively unrecognized in the global carbon cycle. It makes up 16 percent of the Earth’s methane emissions compared to 1 percent of discharge from oceans.
Methane is produced by microbes at the bottom of the lakes that ingest organic matter that falls into the water from plants and trees near the shore. According to the study made, the amount of methane emitted varies depending on what goes in the lake.
The team of scientists conducted tests that compared the effect of coniferous and deciduous trees with debris coming from cattails. It was found out methane from cattails is 400 times more than that produced by conifers.
Dr. Andrew Tanentzap of the University of Cambridge said that cattails do not have similar chemicals. Because of this, they no longer stop microbes from producing methane.
The team also discovered that a new mechanism has the possibility of freshwater lakes to produce more greenhouse gases. According to them, the warming climate which promotes the growth of aquatic plants triggers a damaging feedback loop in natural ecosystems.
To assess the impact, they studied species distribution models that predict how plants are going to change their ranges under different climates. It showed that different aquatic plants move north towards places with warmer temperatures and surrounded by lakes, which causes these plants to have more habitat.
The number of northern lakes occupied by cattails could double between 2041 and 2070. It could increase methane production by about 73 percent during growing season.
Methane production is currently underestimated in global climate models. The study was able to explain the mechanism by which freshwater lakes may generate more methane than what was previously predicted.