Methane is changing the climate

Methane is a greenhouse gas. Its heat-trapping capacity is twenty times greater than that of carbon dioxide. Currently, there is little methane in the atmosphere, but this was not always the case. Methane is suspected of causing numerous ecological catastrophes in the past, including in the late Paleocene—55 million years ago.

Many species of marine organisms became extinct at that time, as Earth's temperature suddenly rose by 7°C. Catastrophic climate change was caused by methane emissions from submarine deposits disintegrating due to the rising ocean floor. During the Ice Age, when significant amounts of water were trapped in ice sheets, ocean levels dropped by 140 meters. The reduction in pressure caused hydrates to disintegrate, sometimes explosively – craters 700 meters in diameter and 350 meters deep have been discovered on the floor of the Barents Sea. Similar craters were discovered at Blake Ridge in the Atlantic. Methane escaping into the atmosphere caused climate warming and mitigated the effects of glaciation.

During the warmer periods of the Ice Age, sea levels rose, far exceeding their present level. The sea encroached on permafrost areas, where, just as today, methane ice deposits existed. The temperature of the frozen ground rose, causing the hydrates to break down. In this case, the gas intensified warming and accelerated the melting of further ice sheets.

We still know little about the relationship between climate and methane hydrates, but it is certain that they are of great importance. Efforts are underway to estimate methane emissions, as hydrate deposits are unstable. Images from the Gulf of Mexico seafloor show gas plumes rising above sediment domes that cover methane ice cushions. High emissions have also been observed in the Sea of Okhotsk and in canyons that cut through the Blake Ridge deposit.

Ocean warming is causing concern among researchers: the amount of methane contained in hydrates exceeds the current concentration of this gas in the atmosphere by 3,000 times. Therefore, there is reason to be concerned...

Methane escaping from submarine sediments doesn't always form massive deposits. On ocean slopes, it often fills only certain crevices, cementing loose sediments. This effectively immobilizes the slope. If the icy cement breaks, the slope slides downhill. The problem seems trivial—what harm, besides spooking fish, can landslides cause? Well, they can—undersea landslides generate tsunamis. For the inhabitants of the Bahamas, the Virgin Islands, and Hawaii, it's a matter of life and death. The entire Bahamas, with its steep slope plunging 5 km into the ocean, is practically held together by clathrate cement. Evidence from the recent past serves as a reminder of the scale of the threat: 8,000 years ago, a large chunk of continental slope near Trondheim slid 800 km from its original location into the Norwegian Sea. The volume of the loosened rock mass is estimated at 5,300 km³! The immediate cause of this gigantic landslide was likely the disintegration of hydrates cementing the slope.