Birth of North Atlantic Ocean 55m years ago caused rapid global warming

<span>Photograph: NOAA Office of Ocean Exploration and Research/AP</span>
Photograph: NOAA Office of Ocean Exploration and Research/AP

About 55 million years ago, the remnants of the supercontinent, Pangea, ripped apart. North America went one way; Europe the other, and the North Atlantic Ocean flooded in to fill the gap. Global temperatures rose by more than 5C and many species went extinct. Quite why the world warmed so quickly has long been a puzzle, but a new study reveals that the rapid warming was driven by methane emissions associated with the ocean birth.

Scientists onboard an ocean drilling expedition collected rock samples from ancient volcanic vents that were active during the birth of the North Atlantic Ocean. Much to their surprise, analysis of the rocks showed that gas release from the vents happened in very shallow water – less than 100 metres. Their findings, which are published in Nature Geoscience, suggest that methane released from these hydrothermal vents would have escaped directly into the atmosphere, causing rapid global warming (unlike methane emitted from deep sea vents, which is mostly converted to carbon dioxide – a far less potent greenhouse gas – as it bubbles up through the water).

The rocks also show that the earth did recover from this episode, but that it took many millennia for the climate to cool down again: an uncomfortable truth when considering the consequences of the global heating occurring right now.