How will permafrost affect and be affected by global environmental change?

Permafrost is defined as ground that remains at or below 0°C for at least two consecutive years. Permafrost underlies approximately 25 % of the land area in the northern hemisphere and can be up to 1500 m thick. Under current climate-change scenarios, permafrost degrades from both the top and bottom, increasing the depth of the “active layer”, and the extent of talik formation.

The deepening of the active layer could trigger the massive decomposition of organic matter stored in the first three meters below surface. The most recent estimates put the organic carbon pool in permafrost at 50% of the global soil organic carbon pool. This pool is equivalent to twice the amount of carbon in the atmosphere. The decomposition processes would lead to the emission of vast quantities of greenhouse gases, including methane and carbon dioxide, which could greatly affect the global climate.

Under the sea, permafrost occurs as subsea permafrost. Its presence on Arctic shelves is intrinsically linked to the occurrence of gas hydrates which are released to the atmosphere through “holes” in the permafrost, called gas seeps. Its exact distribution on the shelves of the Arctic has not yet been correctly assessed, which hampers the attempts to correctly depict the mechanisms of gas hydrate occurrence and release.

In alpine areas, permafrost is responsible for the occurrence and the preservation of landforms that could evolve dramatically, resulting in large scale natural hazards for alpine valley settlements. In the Arctic, rapid coastal erosion of permafrost is expected to increase dramatically following the drastic reduction of summer sea ice extent, threatening the existence of Inuit communities.

Permafrost observation and monitoring is probably one of the most important challenges of the twenty-first century

More information on theIPA website

What is the potential level of positive feedback that may come with the release of methane in the permafrost regions and continental shelves?

Given the potency of methane as a greenhouse gas, and also given the tremendous amount of methane stored both in the permafrost regions as well as the continental shelves, critical research needs to be done as to the level of positive feedback that may occur as some of this methane being released.

Massive releases of methane in earth’s past have played a pivotal role in dictating the direction and degree of climate change. While much attention has been given to carbon dioxide releases and sequestration, only a few scientists are currently studying methane releases going on in the thawing permafrost regions. Much more research needs to be conducted. The obstacles to doing this will be to move the focus of the press and policy makers from primarily carbon dioxide, to methane, as it is far more potent a greenhouse gas, and much more prone to significant positive feedback loops.

How long can the Earth System sustain the present rate of human-induced global-environmental change?

Humans are modifying the planet at an alarming rate. Cropland and pasture now cover almost 50% of the entire land surface. This has led to massive habitat destruction, fragmentation and pollution and, together with overhunting, is causing a critical loss in biodiversity. Agricultural pollution is also having a devastating impact on aquatic and marine ecosystems which, together with industrial fishing, is causing collapse of key species populations within these ecosystems. Industrial pollution and burning hydrocarbons is causing polar warming which threatens to destabilize the remaining ice-sheets and reservoirs of methane stored in the polar oceans and permafrost. With populations in the US, China and India still rising, these clearly unsustainable practices are set to continue. The critical question is how long can planetary environmental processes continue to function before these human-induced changes trigger negative feedbacks that result in a switch to an alternate and less supportive Earth System state?