Hidden climate feedbacks could amplify global warming by 30 percent

The planet itself may be quietly working against efforts to slow climate change. 

New research shows that as temperatures rise, natural systems such as thawing permafrost, drying wetlands, and bigger wildfires could amplify global warming by roughly 20 to 30 percent.

This would add an extra 0.2 to 0.4 degrees Celsius on top of whatever humans directly cause this century.

The study represents the largest effort yet to quantify these effects, bringing together researchers from Stanford University, Spark Climate Solutions, the Environmental Defense Fund, and the Woodwell Climate Research Center.

Researchers have suspected for years that rising temperatures wouldn’t just result from human emissions. 

Thawing permafrost releases ancient organic matter that begins to decompose.

Warmer wetlands and lakes release more methane, particularly in the tropics, while drier landscapes fuel larger wildfires that burn through carbon long locked away in forests.

This new study is the first major attempt to put hard numbers on all four of these feedbacks at once, covering both carbon dioxide and methane emissions from permafrost thaw, wildfires, wetlands, and inland waters together.

“What surprised us was the size of the feedback: we found that natural systems could amplify global warming by 20 to 30 percent,” said Sam Abernethy, a research scientist at Spark Climate Solutions. 

“This hidden multiplier is missing from the models guiding climate policy, so those models are likely underestimating how much warming is coming – and overestimating how much carbon we can still afford to emit.” 

“To close that gap, we need to understand these processes better and build them into the models we rely on.”

Permafrost is doing half the damage

Of the four feedbacks studied, permafrost thaw stands out as the single biggest contributor. According to the research, it accounts for roughly half of all the anticipated warming-induced emissions.

Study co-author Christina Schädel is a senior research scientist at the Woodwell Climate Research Center.

“Permafrost scientists have long warned that thawing soils would become a significant emissions source as the planet warms. This paper shows that permafrost thaw accounts for half of the anticipated warming-induced emissions,’ said Schädel.

“Warming-induced emissions are already in motion, and they scale with every fraction of a degree.”

“Every little bit of warming we can avert today matters for what the climate looks like in the long term.”

Not just a future problem

Even in a future where human-caused emissions hit net-zero, these natural feedbacks wouldn’t simply switch off.

Under a stronger climate action scenario known as SSP1-2.6, the researchers project these feedbacks could still add about 0.2°C of warming by 2100. Under a higher-emissions scenario, SSP4-6.0, that figure roughly doubles to around 0.4°C.

That’s not a small technicality, according to co-author Robert Jackson, chair of the Global Carbon Project at Stanford. 

“We’ve expected warming to boost the carbon cycle for years and now we’re seeing it happen in real time. This paper provides the numbers to support substantial emissions increases from permafrost, wetlands, freshwaters, and wildfires,” Jackson said.

“The results are a wake-up call, and it’s imperative that they be included in the next generation of climate policies. Failure to do so will make meeting the world’s climate goals less and less likely.”

A blind spot in models guiding policy

Perhaps the most consequential finding here isn’t the size of the effect; it’s the fact that most Earth system models don’t currently account for it at all. 

These warming-induced emissions are largely absent from the models used to project how temperatures will respond to human emissions, meaning current climate forecasts are likely underestimating how much warming is actually coming.

Researchers around the world are now working to close that gap, comparing different models of these feedbacks and pushing to get them incorporated into major policy and planning processes, including future IPCC assessments.

“This research makes clear that the earth and climate system doesn’t stand still while we debate policy,” said co-author Brian Buma, a senior climate scientist at the Environmental Defense Fund. 

“Emissions from permafrost, wetlands, and wildfire could meaningfully erode our remaining time to warming thresholds – and they are unaccounted for in most scenarios.”

“This means rapid fossil fuel emissions reductions are even more urgent than current projections suggest. The good news is that it’s in our hands – lower emissions now limit how severe these feedbacks become.”

Still within human control

There’s a hopeful thread running through the findings. 

The amount of extra warming these natural systems generate scales directly with how much warming humans cause in the first place.

Cut direct emissions, and these feedback emissions shrink along with them.

Senior author Benjamin Poulter from Spark Climate Solutions said the findings show why warming-driven emissions need to be better tracked and accounted for.

In other words, these feedback loops aren’t fixed. How powerful they become still depends in part on how much additional warming humans cause.

The study is published in the journal Environmental Research Letters.

—-

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates.

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

——