Why do we call permafrost “eternal” and is it correct? Let's delve into this question with an expert from AIM Carbon.

Permafrost refers to a layer of soil, rocks, and sand that has remained frozen for more than two years. The ground temperature in these areas does not rise above 0°C for extended periods, ranging from several years to millennia. However, ecologists in recent years argue that the term “eternal permafrost” is inaccurate. It is more appropriate to refer to it simply as “perennial permafrost.” Here’s why:

There is a common misconception that permafrost never thaws. In reality, not all permafrost regions are constantly covered with snow or ice. Under certain conditions, during warmer months, the top layer of permafrost can thaw and refreeze as temperatures drop. This top layer, known as the active layer, can vary in depth from 10 centimeters to several meters. 

Frozen soils are conventionally categorized into three types:

•  Short-term — the ground freezes for a few hours or days;
•  Seasonal — the ground freezes for several months;
•  Perennial — the permafrost persists for hundreds or thousands of years.

There are intermediate forms and transitions between these categories. Permafrost formed several million years ago in dry, cold climates with a thin ice cover. It is a global phenomenon found on nearly all continents, excluding Australia. About 25% of the world's landmass is covered by perennial permafrost, with more than 60% in Russia.

Recent international studies show that permafrost is not eternal. According to 2019 observations, due to climate change, the average temperature of perennial permafrost has increased by 0.29°C to 0.12°C across its extent.

The deepening climate crisis over recent decades has disrupted the stability of permafrost, with increases in atmospheric carbon dioxide and methane levels. This explains the current glacier melting and climate changes.

“In the last decade, permafrost has been melting faster than ever before, due to climate warming and human-induced disturbances to the permafrost layer. The ongoing degradation of permafrost, as current research indicates, justifies replacing the traditional term with 'perennial permafrost,' which is more relevant today,” comments Alexey Mamedov, AIM Carbon expert and leader of the project on preserving perennial permafrost and reducing greenhouse gas emissions.

Global warming has caused irreversible changes to the climatic conditions of our planet's most vulnerable regions, disrupting the balance of once stable and unique natural phenomena such as permafrost.

Permafrost is changing just like other elements of the biosphere, thus, it is now more accurate to call it "perennial" rather than "eternal permafrost."