Mongabay · Climate & nature

Natural emissions could amplify global warming by up to 30%, study finds

Greenhouse gases from thawing permafrost, wetlands, wildfires, and freshwater systems could add 0.2°-0.4°C to global warming by 2100, amplifying human-caused warming by 20-30%. Methane accounts for about half of this additional warming.

Most climate models exclude these natural feedbacks, suggesting current warming projections may be too low and carbon budgets too generous. This study is the first to combine these four natural emission sources to quantify their impact.

As the planet warms, thawing permafrost releases ancient organic matter, wetlands and freshwater microbes produce more methane, and drier forests burn more frequently, all releasing greenhouse gases.

The authors warn that future warming projections are likely underestimated as many climate models exclude these natural feedbacks. They aim to improve modeling for future IPCC assessments.

While cutting human emissions is critical, some natural sources, once triggered, may not have an "off switch." This has led researchers to explore methods for removing methane from the atmosphere.

Potential methane removal strategies include enhancing natural ecosystems' absorption capabilities and using reactors to oxidize methane. Unlike CO2 removal, methane removal does not require long-term storage.

Natural methane sinks like forest soil microbes and microbes on tree bark are being studied for their potential to absorb atmospheric methane. Protecting these ecosystems is key.

The study acknowledges limitations, noting that real-world warming could be higher or lower due to unconsidered offsetting processes or other emission sources. Uncertainty also stems from limited direct measurements.

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