What is Permafrost?

Imagine soil, gravel and sand stuck together by ice. That is what we call permafrost.

Soil, gravel and sand? Wait… how come? And where? Let’s first start by explaining what permafrost is. It is ground that is permanently frozen for at least two years in a row (if you want to be precise!). Ground that remains frozen for more than 15 days is called seasonally frozen ground (how original…). If it freezes for less that 15 days it’s called… intermittently frozen ground.

How thick can the permafrost layer be? It can go from 1 meter to 1.000 meters/1km thick and you can find it in regions where it is usually freezing, mostly by the north and southern poles of our planet.

Can you always see it? Not necessarily, permafrost can even be found under seabeds! It is also covered by a smaller layer called the active layer which is not frozen. Imagine the icing on your cake being the active layer and once you cut it, you can see the inside of the cake/ground. This is what we call permafrost.

Why doesn’t the active layer freeze? It does, but not all year long. This is what differentiates it from the layer of permafrost below it. This is why you will not always see permafrost covered in snow! Why is this information important? Do you remember how ice freezes around an object and protects it from the outside world, well it can be useful for some things such as protecting grains from all over the world, but it can also contain threatening elements that could be dangerous to humankind if they are liberated (viruses, bacterias,…).

Do you want the good news or the bad news first? The bad one being that with climate change and global warming, these layers are melting, releasing water (yes, ice melts…) and greenhouse gases trapped within the layers. Scientists believe that our planet’s permafrost increased 6 extra degrees during the 20th century. Not good… How does that have an impact on the release of greenhouse gases? The organic carbon/plants that were once trapped could not decompose because of the cold. With global warming, these materials reach out to the surface and therefore get in contact with warmer temperatures, allowing them to decompose and release carbon dioxide and methane (do not forget to read our article about our love/hate relationship with carbon). The other bad news is that melting permafrost creates a not so solid soil for us to build on. Older buildings once built on cold permafrost will therefore find themselves on not so solid permafrost and therefore not be stable… this could destroy a lot of infrastructure!

So what’s the good news? The good news is that now you know what permafrost is! How can we preserve it and avoid more bad news (we are sick of all the bad news), well once again, by avoiding global warming… It is easier said than done but if you are aware of the situation of our permafrost, we are already one step closer! Well done explorer!

See you next week for a new MANOA Nature post!