Bugs Ready to Munch on Climate Time-Bomb
Many strands of our climate's future criss-cross in the far north of the planet. The frozen Arctic is one of the fastest warming parts of our globe, so perhaps that shouldn't come as a surprise. Here you will find fast-shrinking ice-caps; fabled sea-ice passages that have newly opened; mysterious methane hydrates, buried in cold sea-muds, that could one day release a stupendous global warming belch. And frozen bugs.
Surprisingly, it is the frozen bugs in the permanently iced soils – or permafrost – of the Arctic that has scientists worried. Those bugs are sitting in a climate time-bomb; some 1,600 billion tons of carbon that's been locked into the icy soils for millennium. It comes from the dead remains of plants that lived in the far north before the last Ice Age. The bugs were locked in place too, and for them, that rich organic matter is food for when the soils next melt.
And that permafrost melting is already starting in places – so how those defrosted bugs respond is critical in deciding what happens to the massive permafrost carbon store. Which is why scientists from the Lawrence Berkeley National Laboratory have been looking at the gassy effluence of the permafrost microbe community, in n a study just published in Nature.
They have found that, when the bugs spring back to life, they start munching on the dead plant remains straight away – producing methane and CO2 in equal measure. Both are important greenhouse gases, but methane has a stronger short-term boost to warming. But the researchers noticed that the methane production slowed down within a couple of days; it seems that some bugs seem to find methane a tasty alternative food for themselves.
That is possibly good news, if the same story pans out for the real-world defrost of the permafrost. Methane is twenty times more potent a greenhouse gas than CO2. But the team also found a worrying sign that another greenhouse gas – nitrous oxide – may be a player too. No microbes seem to put this on their menu, so it could be released in higher quantities than previously thought.
Ultimately, though, the only way to avoid putting Arctic bugs in charge of the planet's thermostat would be to avoid trigger further melt-off in the far north. And that requires us humans to get a handle of our own gaseous pollution – and to do so a lot more quickly than has so far been managed.