The global methane bomb is starting to detonate

A hotter planet could be losing its ability to absorb our pollution.

- David Fickling

For all the damage that humanity is causing through our production of greenhouse gases, the numbers involved can seem impossibly slight.

Every year, we release about 9.6 billion tonnes of carbon into the atmosphere as CO2 or carbon dioxide – but there are about 58 trillion tonnes stored away in organic and fossil matter in the atmosphere, land and oceans.

For decades, that has suggested an alarming prospect. By heating the planet, we risk changing the delicate conditions that ensure those trillions of tonnes stay locked up in soils, plants and seawater. Tip the balance too far, and we might provide the catalyst for these immense natural reserves to start disgorging themselves, like a bottle of soda fizzing up when it's opened.

The result could be a "methane bomb" – a rapid and devastating release of greenhouse gases that could overwhelm our best efforts to hold back warming.

To date, there's been hearteningly little evidence that such so-called climate feedbacks – where climate change triggers natural processes which then accelerate warming in a self-amplifying spiral – are occurring on a scale we should worry about.

The Intergovernmental Panel on Climate Change's latest assessment in 2021 found warming and cooling feedback effects are essentially cancelling each other out. As the temperature rises, more sea spray, dust and other fine matter are lofted into the atmosphere, helping to reflect more of the sun's warming rays back into space.