A fungal solution to climate change?

The fight against future climate change may have an unexpected ally, in the form of mushrooms living on the soils of northern Spruce forests of Alaska, Canada and Scandinavia.

Steven Allison and Kathleen Tresede from the University of California Irvine conducted experiments in Alaska and found that when temperature increases, fungi living on the forest floor dry out and emit less carbon dioxide, the opposite of what the researchers expected to find since colder climates are thought to slow down the processes by which fungi produce carbon dioxide.

The study, published in the journal Global Change Biology this week, involved Allison and Tresede going out into the forests of Alaska and setting up several small greenhouses. At the start of the experiment - the beginning of the growing season in May - the scientists kept the conditions inside the greenhouses the same as in nearby control plots. Then, they closed the greenhouses and the temperature of the air went up by 5 degrees Celsius, while the temperature in the soil went up by 1 degree.

By carefully measuring the gases in all these experimental plots they found that by the end of the growing season in August, the amount of carbon dioxide produced by the soil in the greenhouse plots was around half of that produced in the unheated control plots.

Allison and Tresede found that there was about half as much fungi inside the heated greenhouses as in the unheated plots, indicating that when the temperature increases, much of the fungi die while some become inactive and stop producing as much carbon dioxide.

What we don't currently know is whether this change in carbon production will have a significant effect on the climate. Halving of the CO2 output with a 5 degrees increase in temperature certainly sounds like a major change. And this could be particularly important since northern forests are thought to lock away half of the world's soil carbon.

But of course we know very little about how the ecosystem as a whole might respond and adapt to increasing temperature over the longer term and what other changes might be triggered. Ecosystems are notoriously complex, unpredictable things.

There is also the possibility of knock-on effects of this reduction in fungal activity. The soil fungi are doing a really important job of breaking down dead organic matter like fallen leaves, so presumably, halving their numbers could well have an important effect on the functioning of the ecosystem.

While these findings certainly help us understand a little better what is going on and for once this is something that could help alleviate the problems of climate change rather than make them worse, but the picture is still not clear cut and this certainly won't mean the end of global warming.