Permafrost

The impacts of permafrost degradation range from local to global. Locally, permafrost thaw can lead to ground subsidence, which has dangerous and costly consequences. Already, harmful accidents have occurred with the collapse of residential, industrial, and oil and gas infrastructure built on thawing permafrost and many communities are being forced to relocate. Globally, immense amounts of carbon dioxide and methane released by thawing permafrost will amplify the current warming trend; it’s estimated that up to 1600 Gt of carbon are stored in permafrost, nearly twice as much as is in the atmosphere.

Changing permafrost extent

This analysis uses modeled soil temperature data to project the vastly shrinking extent of permafrost in the Arctic and the surrounding high latitude region. We represent the likelihood of permafrost extent as a function of warming above pre-industrial levels. Seven general circulation models (GCMs) from the 6th Coupled Model Intercomparison Project (CMIP6) were used that fit the following criteria: available surface air temperature, available soil temperature to at least 3 m below the surface, and horizontal grid-spacing of approximately 1° latitude and longitude. All of the GCMs used have integrated land surface schemes that represent soil hydrology processes.

Considering present conditions, most CMIP6 models slightly underestimate the current land area of permafrost coverage relative to observations. Considering the future, however, models are expected to underestimate the feedbacks that will further contribute to permafrost degradation. For example, the frequency and severity of wildfires—which are not well represented in models—in the Arctic have increased in recent decades at alarming rates. Not only do wildfires contribute to permafrost thaw by burning the insulating layer above the frozen ground, but they exacerbate warming on a global scale by burning carbon-rich biomass.