Northern permafrost regions, areas of permanently frozen ground, are undergoing rapid changes due to global warming. These changes pose a potential risk to the climate, because permafrost stores enormous amounts of carbon—more than double the amount currently in the atmosphere.

Melting permafrost releases carbon into the atmosphere, which can lead to an increase in global warming. This process happens in two ways:

• When organic matter decomposes in the presence of oxygen, carbon dioxide (CO₂) is released.
• Methane (CH₄) is released in low-oxygen environments such as lakes and waterlogged soils.

Methane is a much stronger greenhouse gas than CO₂, meaning it traps more heat in the atmosphere. Melting permafrost is therefore leading to more methane release, which is of particular concern.

In addition to carbon, permafrost also contains nitrogen. Nitrous oxide (N₂O), another strong greenhouse gas, is released during the decomposition of organic matter.

Scientists from the Global Carbon Project analyzed greenhouse gas emissions in permafrost regions from 2000 to 2020. They found that:

• Permafrost is currently a moderate CO₂ sink, storing 29 to 500 million tons of carbon per year.
• Boreal forests in Canada and Russia absorb significant amounts of CO₂ due to increased plant growth and longer growing seasons.
• At the same time, lakes, rivers and fires are a source of CO₂.
• Wetlands are the biggest source of methane, while melting permafrost leads to more wetting of the soil.
• The largest sources of nitrogen oxide emissions come from dry tundra and boreal forests.

Over a 100-year horizon, the effect of all three greenhouse gases on global warming is nearly neutral, as CO₂ capture offsets the warming effect of methane and nitrous oxide. However, in the short term of 20 years, greenhouse gas emissions from permafrost are a net source of warming, mainly due to the strong warming potential of methane.

Future greenhouse gas emissions from permafrost regions are uncertain, but there are concerns that methane emissions will continue to rise. Earth system models suggest that CO₂ sequestration could continue into the 21st century, but these models often fail to account for local permafrost collapse and extreme fires, which can lead to rapid increases in emissions.

Fires in permafrost areas are a growing problem. For example, wildfires in Siberia in 2021 and Canada in 2023 released huge amounts of carbon, reducing and potentially reversing the effect of permafrost trapping CO₂.

In conclusion, permafrost represents a potential threat to the climate. The only way to prevent the release of carbon and other greenhouse gases from the permafrost is to quickly reduce and then stop greenhouse gas emissions from human activity. (Co2AI)