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Climate ‘feedback loops’ could add significantly to global warming, study finds

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Natural changes triggered by rising temperatures could amplify global warming by as much as 30% by the end of the century, according to new research examining climate “feedback loops.”

The study, published in the journal Environmental Research Letters, examined greenhouse gas emissions from thawing permafrost, wetlands, freshwater systems and wildfires.

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Scientists have long known that warming caused largely by the burning of fossil fuels can trigger natural processes that release additional carbon dioxide and methane. Those gases then contribute to further warming, creating a feedback loop.

Researchers found that these natural emissions could amplify warming by 20% to 30% by 2100, potentially adding another 0.2 to 0.4 degrees Celsius to average global temperatures. The amount would depend in part on how quickly countries reduce human-caused greenhouse gas emissions.

The process can take several forms. Rising temperatures thaw permafrost, allowing greenhouse gases stored in frozen soils to escape. Hotter and drier conditions can contribute to more intense wildfires, releasing carbon stored in forests. Warming wetlands, lakes and other freshwater environments can also increase emissions of methane and carbon dioxide.

The researchers say emissions from such natural sources are not adequately included in many climate projections used to guide government policy.

The study found that reducing fossil fuel emissions would also limit the additional warming produced by natural sources. Under a scenario involving rapid emissions reductions, feedback loops would add an estimated 0.2 degrees Celsius of warming. Under a higher-emissions scenario, the increase could reach about 0.4 degrees.

The findings add to concerns about climate tipping points, in which changes to major natural systems could accelerate warming or become difficult to reverse.

Researchers stressed, however, that the findings do not mean uncontrolled or runaway warming is inevitable. Instead, they said the study demonstrates how human-caused warming can set in motion natural processes that further increase temperatures.

Source: The Guardian

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