“Jekyll & Hyde” peat bogs turn up the heat

We’re all used to the idea that rising levels of carbon dioxide (CO2) in the air are causing our climate to change. And we’re used to the idea that it’s our burning of oil, gas and coal that’s driving the process. But this new study shows that extra CO2 is getting into the atmosphere by a completely different route – and it’s all our own fault.

For thousands of years, peat bog plants have taken up carbon dioxide from the air and turned it into peat (part-decomposed plants) that can reach several meters in depth. This is clearly a “good process” because it helps to remove the CO2 we release by burning fossil fuels.

“But now there are signs that nitrogenous gases in air pollution can make peat bogs give off more carbon dioxide than they lock-up”

The amount of carbon contained in peat is not far off the total amount of carbon dioxide in the entire atmosphere by some estimates. The carbon is held in place by what Prof Freeman described in Nature recently as an “Enzymic latch”. In this, special chemicals called “phenolics” are produced by peat-bog plants that can stop plants decomposing after they’ve died. “They’re a bit like preservatives in food” explained Prof Freeman “only in this case they’re preserving huge stores of carbon in the form of peat, rather than food”.

The study in PNAS tells how a network of scientists led by Chris Freeman and his colleague Luca Bragazza from Italy, have studied samples taken from bogs all around Europe with varying levels of nitrogen in their rainfall. The results showed very clearly that bog plants growing in areas with higher levels of nitrogen form less phenolics. This is worrying because the less phenolics the plants produce, the weaker the enzymic latch becomes. This can ‘jump-start’ decomposition back into life and cause a ‘Jekyll and Hyde transition’ in the character of our bogs: Instead of being “good guys” – helping us by taking up our fossil fuel CO2 emissions, they become “bad guys” and start giving off even more carbon dioxide to the atmosphere than they take up.

Perhaps the most worrying aspect is that these results suggest that even if we managed to stop all further fossil fuel CO2 emissions (by switching to biofuels for example), atmospheric CO2 levels would continue to rise due to CO2 release from peat bogs.

Clearly putting an end to global warming is going to be more difficult than we thought. We need to address other aspects of air pollution too.