New researchers have found that as the planet warms, the amount of plant matter in freshwater lakes could rise and lead to double the amount of methane and carbon dioxide (CO2) could almost double. The study from the University of Cambridgeshire simulated the effects of climate change on freshwater lakes in Canada. They found that as the water warms, plant matter in the lakes rises according to the research published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS).
This is because of longer summers and milder winters create greater diversity as plants decompose and are taken by microbes in the water.
Ultimately, the more plant matter translates to more microbes increase the amount methane and CO2 being released by an average of 1.5 to 2.7 times.
Dr Andrew Tanentzap in Cambridge’s Department of Plant Sciences, who led the research, said: “What we’ve traditionally called ‘carbon’ in freshwater turns out to be a super-diverse mixture of different carbon-based organic molecules.
We’ve been measuring ‘carbon’ in freshwater as a proxy for everything from water quality to the productivity of freshwater ecosystems. Now we’ve realised that it’s the diversity of this invisible world of organic molecules that’s important.”
“Climate change will increase forest cover and change species composition, resulting in a greater variety of leaves and plant litter falling into waterways.
“We found that the resulting increase in the diversity of organic molecules in the water leads to higher greenhouse gas concentrations.
“Understanding these connections means we could look at ways to reduce carbon emissions in the future, for example by changing land management practices.”
Dr Tanentzap said that the next part of the study will focus on how sediment formed of the lake floor will effect greenhouse gasses, stating that discovery could help determine just how long humanity has to battle the consequences.
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Writing in a think piece for the Conversation, Dr Tanentzap said: “Work also remains to understand fully the role lakes play in the carbon cycle.
“Not all organic matter that reaches lakes is digested by microbes. Some sinks to the lake floor to form muddy sediment, locking away carbon.
“The amount of sediment formed will also increase with climate change, but we don’t yet know by how much – and so to what degree this increase in stored carbon will offset the increased greenhouse gas emissions from lakes.
“Answering this question will be crucial in improving the accuracy of carbon accounts – and assessing how much time humanity has to balance them.”