Press release – Is there a link between climate warming and methane emissions from the Arctic Ocean floor?
There was a massive methane release from the ocean floor in the Arctic during the last Ice Age, a new study finds. Release of the greenhouse gas coincided with a period of global warming 13 000 years ago. This data was recorded in, and retrieved from the shells of the smallest creatures on the planet – foraminifera.
Frozen deposits of the greenhouse gas methane, so called gas hydrates, lay in huge amounts under the ocean floor in the Arctic. They are sensitive to climate change and warming of the ocean. 170 m3 of methane gas is concentrated in 1m3 of frozen methane. Potential escape of methane from the ocean into the atmosphere can be significant if hydrates melt.
– The stability, longevity and significance of the Arctic methane hydrates for the global climate budget are poorly understood. Some of the smallest creatures on the planet, foraminifera, may however provide some answers, says associate professor Giuliana Panieri at the Centre for Arctic Gas Hydrate, Environment and Climate (CAGE) – University of Tromsø, The Arctic University of Norway. Panieri is presenting the new results this week at the General Assembly of the European Geosciences Union in Vienna.
Foraminifera residing at the ocean floor store clues to understanding methane release in their shells. Giuliana Panieri and colleagues have examined shells of foraminifera for several isotopes to reveal historical emissions of methane as far back as 16 000 years.
Through sediment cores from the ocean floor they have been able to determine that the Earth suffered a long and intensive methane emission 13 000 years ago. This coincided with global warming during the final stages of the last Ice Age. The evidence of emissions from the Earth’s ocean floor is similar to the data found in the ice core records in the Greenland Ice. This means that warming accelerated at the end of the last Ice Age, at the same time as massive amounts of methane were released from the ocean floor.
The big climate question is whether the present global warming will melt Arctic methane hydrates rapidly, and lead to a similar release of the greenhouse gas.
– Warming in the Arctic Ocean will occur faster than in any other region of the world. Methane deposits are especially vulnerable to the warming, as they are found at shallower depths. Climate warming at contemporary rates will not trigger catastrophic release of methane gas from hydrates. But we believe that such release will happen primarily on the Arctic Ocean shelves and upper continental margins.
Predictions are difficult, continues Panieri, because the climate sensitive Arctic is not an easily accessible area. That is why our research ships are deployed extensively across the frozen Arctic to get the data vital for modelling past and future changes.