If you go somewhere very cold and dry, such as the Arctic, and dig deep beneath the ground, you’ll find a layer of permanently frozen soil, called permafrost. What is it, and why is it important?
The permafrost makes it very difficult for trees to grow in these environments, yet they are just as good at taking in carbon dioxide from the atmosphere and storing it as warm, leafy forests.
While the layer of permafrost always stays frozen, the top layer of soil melts during the summer months. It is just deep enough for small plants, such as shrubs, to bury their roots. Like all plants, these shrubs absorb a lot of carbon dioxide, which they use to help them grow.
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A picture explaining how permafrost thaw releases carbon dioxide (Source: Charlotte Ames-Ettridge).
When the shrubs die, they break down in the soil. The carbon they contain is absorbed by the layer of permafrost. As long as the soil remains frozen, the carbon will stay trapped there for millions of years. In fact, permafrost contains around 14% of the world’s carbon! Environments like this, which take in more carbon than they give out, are called carbon sinks.
But climate change is causing the permafrost in some parts of the world to melt. All the carbon stored inside the permafrost is then released into the atmosphere as carbon dioxide or methane, another harmful greenhouse gas. Because carbon dioxide traps heat from the sun, it leads to even warmer weather, causing more permafrost to melt. It is a dangerous, never-ending cycle.
As many regions begin to lose their permafrost, they are releasing more carbon than they take in. This means they are no longer carbon sinks, but carbon sources. Scientists predict that we will see more and more carbon sinks turn into carbon sources in the future. That’s why it’s important for governments to take action against climate change and decrease the amount of carbon emissions we release!