European scientists have discovered more than 250 plumes of methane (CH4) gas bubbles rising from the seabed of the West Spitsbergen continental margin in the Arctic, at a depth of 150 to 400 meters. The warming of Arctic currents by 1° over the last 30 years has triggered the release of methane, a potent greenhouse gas, from methane hydrate stored in the sediment beneath the seabed. Methane released from gas hydrate in submarine sediments has been identified as an agent of past climate change.
,Methane hydrate is an ice-like substance composed of water and methane, which is stable in conditions of high pressure and low temperature. Thirty years ago, methane hydrate was stable at depths as shallow as 360 meters in the ocean off Spitsbergen. Now, it is not stable – the water is not cold enough – until depths of 400 meters or more. This is the first time that such behavior in response to climate change has been observed in the modern period.
The likelihood of methane being released in this way as the ocean warms in the future had been widely predicted. “Our survey was designed to work out how much methane might be released by future ocean warming; we did not expect to discover such strong evidence that this process has already started,” said Professor Tim Minshull, Head of the University of Southampton’s School of Ocean and Earth Science.
Gas hydrates are found all over the world, with particularly large deposits located off the coast of southeast Asia. Many countries in the region view these hydrates as a valuable source of natural gas. India and China have reported finding massive reserve of methane hydrates off their coasts, which they hope to tap to fuel their growing economies. They, along with Japan, South Korea and Taiwan, have invested millions researching this untapped source of energy.
Some scientists warn that exploiting these reserves could trigger massive releases of methane, a greenhouse gas more than 20 times more potent than CO2. Other believe that the hydrates can be used as a place to store CO2 captured from the atmosphere, replacing every one methane molecule extracted with five molecules of CO2.
Most of the methane currently released from the seabed is dissolved in the seawater before it reaches the atmosphere. However, methane seeps are unpredictable and it is possible that periods of vigorous outflow will occur as the ocean warms further. Furthermore, methane dissolved in the seawater contributes to ocean acidification. Graham Westbrook Professor of Geophysics at the University of Birmingham, warns: “If this process becomes widespread along Arctic continental margins, tens of megatonnes of methane per year – equivalent to 5-10% of the total amount released globally by natural sources, could be released into the ocean.”