Siberian tundra case study

Where is the Siberian tundra?

The Siberian tundra covers 22% of landmass and extends from Eastern Europe to Eastern Asia across countries such as Kazakhstan, China, Russia and Mongolia.

Why is the Arctic experiencing a very fast rate of warming?

• Ice and snow cover reduces with warming temperatures.

• This exposes a surface of rock with a lower albedo, allowing it to absorb more solar radiation and warm the air above it in a positive feedback loop.

Where is carbon stored in the Siberian tundra?

Carbon is mostly stored in the thick layers of permafrost that have accumulated in the Siberian Arctic over eight or more ice advances.

What is permafrost?

Layers of soil that have been permanently frozen for more than two consecutive years, containing organic material.

How is permafrost formed?

• Ice sheets and rock are ground up to form loess deposits downwind.

• Vegetation grows on each new layer of deposits during inter-glacial periods, before becoming frozen in the next ice advance.

• Layers of alternating loess and vegetation continue to form with each glacial/inter-glacial period.

How is carbon released from the tundra?

• Surface layers of permafrost begin to melt due to warming temperatures.

• This exposes frozen organic material, which is subject to decomposition.

• This releases carbon dioxide (or methane in anaerobic, swampy conditions).

How much carbon is stored in the Siberian tundra?

• Between 210 and 450 GtC out of the 1,400 GtC that is estimated to be stored in permafrost globally.

• The Yedoma region (from Eastern Siberia to Alaska) is thought to have particularly rich deposits.

Does the Siberian tundra currently act as a carbon source or sink?

Currently, it acts as a sink. This is because increased atmospheric CO2 + a longer growing season increase vegetation growth, meaning at the moment more carbon is absorbed than released.

How could the Siberian tundra turn into a source and why would this be an issue?

• If more permafrost thaws, more carbon will be released than absorbed, and a positive feedback cycle of increasing warming could be established if a 'tipping point' is reached.