Carbon emissions from thawing permafrost will result in a substantial arctic contribution to climate change

Alaska tundraCarbon emissions from the Arctic will threaten our ability to stay within the 2°C target of limiting global warming set by the UNFCCC Paris Agreement, according to an expert assessment published last week. The assessment, which involved several WHRC scientists, looked at the amount of carbon that will be emitted from the northern high latitudes by the end of the century, including releases from thawing permafrost and absorption by increases in biomass resulting from warming.

The vast majority of carbon in the Arctic is contained in permafrost, which is vulnerable to thawing and degradation under climate warming. However, models suggest that some permafrost carbon emissions may be offset by greater plant growth in the Arctic as the climate warms. The exact amount of emissions is difficult to know, because models either neglect or poorly account for key processes, such as fires, insects, drought, and migrating vegetation, all of which interact and are expected to increase over the next hundred years. A comprehensive survey of 98 experts was undertaken to help fill this knowledge gap.

The expert assessment, recently published in Environmental Research Letters, finds that biomass is unlikely to offset a significant fraction of permafrost carbon emissions after 2050 due to water stress and increased disturbances, such as collapsing coastlines and fires.

According to the study, “Some have dismissed the importance of [the permafrost carbon] feedback, asserting that increases in biomass will offset any carbon losses from soil, or that changes will occur too slowly to concern current governments. Our study highlights that arctic and boreal biomass should not be counted on to offset permafrost carbon release and suggests that the permafrost region will become a carbon source to the atmosphere by 2100 regardless of warming scenario.”

All is not doom and gloom, however. Among the more than ninety experts who contributed to the study were WHRC scientists Scott Goetz, Susan Natali and Brendan Rogers. “One important message from this assessment,” says Dr. Rogers, “is that we very much control the amount of high-latitude carbon that stays in the ground.”

According to Dr. Goetz, “Permafrost emissions during the next 10-20 years are likely to increase, but productive forest and tundra areas will offset some of those emissions.” After that, explains Dr. Natali, “If global CO2 emissions continue relatively unchecked, we could face a real problem as carbon release from permafrost accelerates.” Indeed, the assessment concluded that 85% of carbon emissions from the permafrost zone could still be avoided with aggressive international policies, but that window of opportunity is rapidly closing.

The experts did not always agree on the extent of change. Nonetheless, the overarching message is clear, and according to lead author, Dr. Benjamin Abbott, all of the scientists agreed that “the rate and magnitude of current warming is taking us into uncharted territory in regard to permafrost carbon.”

View the complete article: Biomass offsets little or none of permafrost carbon release from soils, streams, and wildfire: An expert assessment

WHRC is an independent research institute where scientists investigate the causes and effects of climate change to identify and implement opportunities for conservation, restoration and economic development around the world.