Informed Comment Homepage

Thoughts on the Middle East, History and Religion

Header Right

  • Featured
  • US politics
  • Middle East
  • Environment
  • US Foreign Policy
  • Energy
  • Economy
  • Politics
  • About
  • Archives
  • Submissions

© 2025 Informed Comment

  • Skip to content
  • Skip to primary sidebar
Climate Crisis
Danger of Climate Feedback Loops: Lakes now Emit 1/4 of Global Carbon, but heating Could Double It

Danger of Climate Feedback Loops: Lakes now Emit 1/4 of Global Carbon, but heating Could Double It

The Conversation 11/20/2019

Tweet
Share
Reddit
Email

Andrew J Tanentzap | –

Lakes and ponds are the final resting place for many of the Earth’s plants. Rivers collect much of the planet’s dead organic matter, transporting it to rest in calmer waters.

But on a microscopic scale, lakes are anything but calm. An invisible metropolis of microbes feeds on these logs and leaves, producing greenhouse gases as a byproduct.

As a result, lakes may be responsible for as much as a quarter of the carbon in the atmosphere – and rising. New research conducted with my colleagues in Cambridge, Germany and Canada suggests that emissions from freshwater lakes could double in the coming decades because of climate change.

All known life on Earth is made of carbon. When plants and animals reach the end of their lives, microorganisms such as bacteria and fungi come to feast. They feed on the carbon-based remains of other organisms and their waste products — collectively known as organic matter.

As a byproduct of this never-ending feast, microbes release gases such as carbon dioxide and methane into the environment. While each individual microbe releases a minuscule amount of gas, they are the most abundant organisms on Earth, so it adds up. Energy from sunlight can also break the chemical bonds between molecules of organic matter, releasing smaller molecules, such as carbon dioxide, into the environment.

Lakes and land are not isolated systems.
Aaron Burden/Unsplash, CC BY-SA

Some of this degradation happens on the forest floor. But much of the organic matter that falls to the ground ends up in the water. Winds, rain and snow transport it into lakes, or more often into the rivers that feed them.

The amount of greenhouse gases released from lakes by microbes and sunlight is huge. Initial estimates were about 9% of the net carbon released from the Earth’s surface to the atmosphere – that is, the amount released over and above the Earth’s carbon-storing processes.

But, thanks to improved measurements, recent research has revised the figure to as high as 25%. These numbers are substantial given that that lakes only comprise about 4% of the global land surface.

In the coming years, lakes will receive more and more organic matter for microbes to digest. A warming climate will bring more forest cover around lakes and a greater proportion of broad-leaved trees, such as maples and oaks, as compared to needle-leaved trees, such as pines.

Carbon in a thousand forms

To understand how changes to forests will alter the role that lakes play in the carbon cycle, we performed an experiment in two Canadian lakes.

We filled plastic containers with rocks, sand, clay and different amounts and types of organic matter from nearby forests. This was intended to mimic the change in forest cover and composition expected from climate change.

We then submerged the containers in shallow lake waters where organic matter is most likely to accumulate and monitored them for three years.

Using new techniques to analyse the carbon chemistry of water, we found that those containers simulating a level of forest growth expected in the next few decades led to between 1.5 and 2.7 times more greenhouse gases in the water than conditions simulating today’s forest conditions.

The invisible diversity of organic compounds in the water was the most important factor causing this rise – even more important than the diversity of microbes and the overall amount of organic matter.

The likely explanation for this result is that the same microbes can feed on many different types of molecule. So as the number of carbon-based compounds in the water increases, there are more ways for microbes to feed and release greenhouse gases.

They’ll find their way to a lake sooner or later.
Aaron Burden/Unsplash, CC BY-SA

The increase in diversity of organic matter alone was enough to raise greenhouse gas concentrations by about 50%. But the size of this effect nearly doubled in containers with darker overlying waters – a scenario expected in most lakes as climate change brings increased tree cover.

Accurately tracing how carbon makes its journey from land to atmosphere is vital to predict the pace of climate change and mitigate its effects. By better understanding how the vegetation around lakes controls greenhouse gas concentrations in waters, our research can inform whether changing the way we manage land near lakes could help reduce carbon emissions.

For example, we might want to plant fewer aquatic plants such as cattails in lakeside areas, because they produce much higher concentrations of greenhouse gases than organic matter from forests.

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.


Click here to subscribe to our climate action newsletter. Climate change is inevitable. Our response to it isn’t.The Conversation

Andrew J Tanentzap, Reader in Global Change Ecology, University of Cambridge

This article is republished from The Conversation under a Creative Commons license. Read the original article.

——–

Bonus video added by Informed Comment:

Filed Under: Climate Crisis, Soil Carbon Release, Water

About the Author

The Conversation is an independent, not-for-profit media outlet that works with academic experts in their fields to publish short, clear essays on hot topics.

Primary Sidebar

Support Independent Journalism

Click here to donate via PayPal.

Personal checks should be made out to Juan Cole and sent to me at:

Juan Cole
P. O. Box 4218,
Ann Arbor, MI 48104-2548
USA
(Remember, make the checks out to “Juan Cole” or they can’t be cashed)

STAY INFORMED

Join our newsletter to have sharp analysis delivered to your inbox every day.
Warning! Social media will not reliably deliver Informed Comment to you. They are shadowbanning news sites, especially if "controversial."
To see new IC posts, please sign up for our email Newsletter.

Social Media

Bluesky | Instagram

Popular

  • Israel's Netanyahu banks on TACO Trump as he Launches War on Iran to disrupt Negotiations
  • Iran's Hypersonic Missiles Hit Israeli Refinery, Military Sites, as Israel does the same to Tehran
  • A Pariah State? Western Nations Sanction Israeli Cabinet Members
  • Israel: Will Ultra-Orthodox Jews' Opposition to Conscription Bring down Netanyahu's Gov't
  • Will Iran reply to Israeli Attacks with "War of Attrition?" Will its Nuclear Red Line Hold?

Gaza Yet Stands


Juan Cole's New Ebook at Amazon. Click Here to Buy
__________________________

Muhammad: Prophet of Peace amid the Clash of Empires



Click here to Buy Muhammad: Prophet of Peace amid the Clash of Empires.

The Rubaiyat of Omar Khayyam


Click here to Buy The Rubaiyat.
Sign up for our newsletter

Informed Comment © 2025 All Rights Reserved