Scientists Issue Warning: Microbes Hold Key to Climate

Jun 23, 2019

Microbes determine whether salt marshes trap carbon or release it.
Credit jenneva72 / Pixabay

By Becca Cox

A group of nearly three dozen scientists from around the world have issued a warning to humanity: pay attention to microbes. They may be microscopic, but they play critical roles in the Earth’s climate systems and we ignore them at our own peril.

“We live in a microbial world,” explained David Mark Welch, director of the Marine Biological Laboratory’s Bay Paul Center and one of the signatories of the warning in the journal Nature Reviews Microbiology. “Microbes had been around for billions of years before plants and animals evolved. All major biogeochemical functions on this planet came about because of microbes, and continue to be run by microbes.”

Microbes are the major biological influence on climate, aside from human-produced greenhouse gases. As our climate changes, microbes will react in significant ways, but whether those reactions will be beneficial or harmful to the climate is unknown.

“We really have no idea how microbial communities will be responding to the changing climate,” said Mark Welch.

For example, microbes in the ocean are responsible for about half of the carbon fixation on the planet, drawing carbon dioxide out of the atmosphere. But microbes – different species, or under different conditions – also put carbon dioxide into the atmosphere. The effect of rising ocean temperatures on these microbial processes is unknown.

There is similar speculation about changes in changes microbial communities due to ocean acidification and rapidly melting permafrost.

“Microbes will either metabolize all of that carbon in the permafrost and release it as CO2 - potentially doubling or even more tripling the amounts of carbon dioxide in the atmosphere - which would be beyond catastrophic,” said Mark Welch. “We don't know if that's what the microbes are going to do, or if they're going to ignore it, or if they're going to evolve other functions.”

Despite the drastic effects that microbes can have on the climate, most of the attention around climate change has been spent on what we can see and understand, like forests and polar bears.

“It’s impossible to see the microbes, so they are much less on our minds, and much less on the minds of policy makers and people who think about climate change,” said Mark Welch.

It is not only policy makers who can address this, however. Action can be taken at a community level to create healthier ecosystems that encompass microbes. For example, wetlands restoration and flood control projects can influence whether salt marshes suck up or release the powerful greenhouse gas methane. At a personal level, choosing to eat less beef or switching to grass-fed beef can lessen environmental impacts, as bacteria in cows’ guts are major sources of methane in the atmosphere.

“Microbes are everywhere, and they dominate everything that happens on this planet,” said Mark Welch.

Mark Welch says we need a better scientific understanding and popular appreciation of them, and must consider their influences strongly as we address climate change.