Rise in Wildfires Depletes Forests’ Carbon Store

In a warming world, forest fires could be about to put more carbon dioxide into the atmosphere than the trees absorb.

New research by US scientists looked at decades of wildfire incidence in Alaska, and they have found that at least one region is now a net exporter of carbon.

This is a reversal of the normal arrangements, whereby trees photosynthesise tissue from the carbon dioxide in the atmosphere.  As they absorb carbon, they sequester it in roots, timber and leaves, and then in leaf litter in the forest soils.

Fire is a natural hazard, and some geographical zones –the Mediterranean, the US southwest, and Australia – are adapted to periodic fire.

But as the planet warms, there have been increasing levels of fire even in the rainforests of the Amazon and in the boreal forests of the near-Arctic.

The Arctic and sub-Arctic forests contain almost one-third of the planet’s store of terrestrial carbon.

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