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The Breakdown of Natural Systems Could Intensify Warming by 30 Percent

As the planet heats up, tundras are thawing, wetlands are fermenting, and forests are succumbing to larger and more frequent wildfires. The breakdown of these natural systems is unleashing huge volumes of emissions, further intensifying warming from the burning of fossil fuels. According to new research, such feedback loops could amplify human-driven warming by 20 to 30 percent.

Even if humans reach net zero emissions later this century, feedbacks would add another 0.2 degrees C of warming, according to the modeling study, published this week in Environmental Research Letters. And if the world fails to reach net zero, and countries continue to produce some residual emissions through the end of this century, the added warming would be closer to 0.4 degrees C.

The world is already 1.4 degrees C hotter than in the preindustrial era, and fossil fuel emissions continue to grow, putting the Earth on course to surpass 2.5 degrees C of warming this century, scientists say, well in breach of international climate targets. And yet, while the added warming from feedback loops will further hasten the rise in temperatures, emissions from the breakdown of natural systems are largely absent from the most influential climate models, those that inform climate negotiations.

"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," said lead author Sam Abernethy, a researcher at Spark Climate Solutions, a San Francisco-based nonprofit that aims to identify climate "blind spots" and account for them in policy. "To close that gap, we need to understand these processes better and build them into the models we rely on."

The challenges are steep. Feedback loops are difficult to model, and emissions data is lacking in hard-to-reach places, such as Siberia or the Congo Basin. But as Yale Environment 360 recently reported, scientists around the world are now racing to forecast emissions from natural systems.

"If you're not including all the emissions going into the atmosphere, you're hamstrung from the get-go," Brian Buma, a climate scientist at the Environmental Defense Fund, told e360. "People are recognizing that the longer we go without taking these emissions into account, there's just going to be a bigger gap."