Rob Jackson reports:

Controlling methane provides our best, and perhaps only, lever for shaving peak global temperatures over the next few decades. This is because it’s cleansed from the air naturally only a decade or so after release. Therefore if we could eliminate all methane emissions from human activities, methane’s concentration would quickly return to pre-industrial levels. Essentially, humans have released in excess of 3bn tonnes of methane into the atmosphere in the past 20 years. Quashing those emissions within a decade or two would save us 0.5C of warming. No other greenhouse gas gives us this much power to slow the climate crisis.

If the Earth keeps warming, though, reducing emissions from human activities may not be enough. We may also need to counter higher methane emissions in nature, including from warming tropical wetlands and thawing Arctic permafrost. The highest natural methane emissions come from wetlands and seasonally flooded forests in the tropics – such as the Brazilian Amazon forest I recently visited at the Mamirauá sustainable development reserve – and they are expected to rise with warming. Tropical wetlands yield so much methane because they are warm, wet (by definition) and low-oxygen environments perfect for growing methane-emitting microbes.

On my most recent trip there a year ago in July, El Niño [warming of sea surface temperatures] was strengthening and the tropical Atlantic was baking. Ocean temperatures off the coast of Florida approached hot-tub levels of 40C (104F) – close to temperatures suggested for cooking salmon and the highest surface ocean temperatures measured. [Continue reading…]