Rapid climate change 56 million years ago explained

The release of methane from the seafloor was much slower than previously thought during a rapid global warming event 56 million years ago that caused the extinction of many species, a new study has found.
The study led by researchers at the University of Southampton in the UK could allow scientists to better understand the potential effects of rising ocean temperatures worldwide on current and future climate change.
Around 56 million years ago, during the Paleocene-Eocene Thermal Maximum (PETM), temperatures in the deep ocean rose by about five degrees Celsius and sea surface temperatures increased by up to nine degrees Celsius.

The PETM period lasted for about 100,000 years and caused the extinction of many species.
Based on evidence from tiny fossils deposited in sediments at the bottom of the ocean, which record information about the chemical composition of the ocean in their shells, current theories suggest that at the same time as the warming there was a massive release of methane gas from the solid earth into the ocean and atmosphere.
A large proportion of the Earth's methane is stored beneath the oceans in the form of an ice-like material called hydrate.

This hydrate can melt if the ocean above warms, and melting of hydrate provides a widely accepted mechanism for the methane outburst.

However, the research from the University of Southampton and the National Oceanography Centre casts doubt on this mechanism.
Using computer models of the warming process, the researchers simulated the effects of PETM ocean warming on sediments that may have contained methane hydrate and tracked how methane transport mechanisms would have affected its release into seawater.
"Our results show that hydrate melting can indeed be triggered by ocean temperature change, but the result is not necessarily a rapid outburst of methane," said lead author of the study, Tim Minshull, Professor at Southampton.
"This is because the methane gas formed by hydrate melting below the sea floor takes time to travel up to the seabed, and on the way it can refreeze or dissolve and then be consumed by microbes that live below the seabed," Minshull said.

"Only a fraction of the methane may escape into the ocean and the part that does escape may take thousands of years to do so," he said.
"To explain the geological observations by melting of hydrate, much more hydrate must have been present globally than is perhaps reasonable for such a warm late Palaeocene Ocean," said Professor Paul Wilson from Southampton.
"And special transport routes would have been needed - perhaps cracks and fissures - to allow the methane to rise to the seabed quickly," he added.
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Pershing said India should opt for a fuel that is carbon free to reduce its greenhouse gas emissions.

Part of the reason for the US and China being number 1 and 2 respectively in greenhouse gas emissions was due to their failure to address the carbon issue, said Pershing, who is in India as part of the US-India Strategic and Commercial dialogue.
Addressing students on the impact of climate change and the urgent need to address it, Pershing said electricity contributes one-third to GHG emissions, and a collective effort at the global level is necessary to reduce the emissions.
This could be done through use of better technology and also the use of renewable sources of energy such as solar, wind, hydro and nuclear energy, he said.

"I am agnostic about nuclear energy. It is for each country to decide on which source to use. It is necessary to ensure the source does not produce carbon," he said.
To ensure that global temperatures do not rise above 1.5 degrees Celsius, the US government has made it mandatory for all manufacturers to incorporate climate change in every decision, Pershing said.
The US agriculture department is working on processes for farming which lower GHG emissions, he said.
"Climate change makes everything we worry about such as high tides, rains, and droughts worse. We are at the edge and a small tip would lead to chaos," he said.

"Ours is the generation that could change the situation. Our parents did not have the chance to do so and our children won't have it," he added.