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New low for global warming Since 1979, when satellite readings began, the six lowest sea-ice extents
have all occurred in the past six years, from 2007 to 2012. Vast methane reservoir beneath Antarctic ice likely Prof Yash
Pal THIS UNIVERSE
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New low for global warming THE latest news from the Arctic cirlce should be, environmental campaigners say, a global wake-up call. The ice cap covering the top of the world is now smaller than it has been at any point since scientists started to measure it precisely from space. Satellite data released early this week show that the sea ice floating on the Arctic Ocean has reached a record low, retreating further than it has done since detailed records began more than 30 years ago. The US National Snow and Ice Data Centre in Boulder, Colorado, said the 2007 record was broken on Sunday with two or three weeks of the melt season still remaining, suggesting that this year’s sea ice will retreat substantially further than at any time in the satellite era. The snow and ice centre said that the surface area of the Arctic Ocean covered by floating sea ice fell to 4.10 million square kilometres, which was 70,000 square kilometres below the previous record minimum of 4.17 square kilometres set in September 2007. This means that since 1979, when satellite readings began, the six lowest sea-ice extents have all occurred in the past six years, from 2007 to 2012. The sea ice retreat was particularly rapid this August and may have been exacerbated by an intense storm over the Arctic region. However, scientists believe that global warming caused by rising levels of carbon dioxide in the atmosphere is the only plausible explanation for the continued loss of Arctic sea ice, which is one of the most visible consequences of man-made climate change. “By itself, it’s just a number, and occasionally records are going to get set. But in the context of what’s happened in the last several years and throughout the satellite record, it’s an indication that the Arctic sea ice cover is fundamentally changing,” said Walt Meier, a sea-ice specialist at the snow and ice data centre. “The Arctic used to be dominated by multi-year ice, or ice that stayed around for several years. Now it’s becoming more of a seasonal ice cover and large areas are now prone to melting out in summer,” Dr Meier said. Mark Serreze, director of the data centre, said the previous record set in 2007 occurred because of near-perfect summer weather for melting sea ice, with clear skies and intense sunshine dominating the region’s weather. “Apart from one big storm in early August, weather patterns this year were unremarkable. The ice is so thin and weak now, it doesn’t matter how the winds blow,” Professor Serreze said. It is normal for sea ice floating on the Arctic Ocean to ebb and flow with the seasons. It thickens and grows in the cold winter months and melts and retreats again in the summer, reaching a seasonal minimum each summer during early September. However, since 1979 Arctic scientists have observed that the September minimum is significantly smaller in terms of surface area of the ocean covered by sea ice. This trend has accelerated in recent years. Computer models of how the sea ice would respond to global warming initially suggested that the region could be free of summer sea ice by the end of the century. Later models suggested this could occur as early as 2030 or even earlier, but none had predicted the rapidity of the observed loss of sea ice. Sea ice is seen as important because of its disappearance could lead to other important changes to the Arctic environment. One immediate effect is the opening up of shipping lanes that could lead to new oil and gas explorations within the region, triggering political tensions as well as further releases of carbon dioxide from the mining and burning of fossil fuel. The record minimum was announced just two days after the Royal Dutch Shell’s drilling ship, the Noble Discoverer, took advantage of reduced sea ice and started sailing from Alaska to the Chukchi Sea, in anticipation of final US government approval for oil exploration in the region. Scientists have already observed a link between disappearing sea ice and the release of methane, a greenhouse gas that is more than 20 times more potent than carbon dioxide, from beneath the Arctic Ocean. Researchers flying over the melting sea ice reported last May that significant quantities of methane are being released from between the cracks in the ice. John Sauven, executive director of Greenpeace, said that the latest data on how fast the sea ice is in retreat should be a warning to the world. “Let’s be clear about what today means – our planet is warming up at a rate that puts billions of people’s future in jeopardy,” Dr Sauven said. “These figures are the effects of man-made global warming caused by our reliance on dirty fossil fuels,” he said. — The Independent
Vast methane reservoir beneath Antarctic ice likely A vast reservoir of the potent greenhouse gas methane may be locked beneath the Antarctic ice sheet, a study suggests.
Scientists say the gas could be released into the atmosphere if enough of the ice melts away, adding to global warming. Research indicates that ancient deposits of organic matter may have been converted to methane by microbes living in low-oxygen conditions. The organic material dates back to a period 35 million years ago when the Antarctic was much warmer than it is today and teeming with life. Study co-author Professor Slawek Tulaczyk, from the University of California at Santa Barbara, said: “Some of the organic material produced by this life became trapped in sediments, which then were cut off from the rest of the world when the ice sheet grew. Our modelling shows that over millions of years, microbes may have turned this old organic carbon into methane.” Half the West Antarctic Ice Sheet and a quarter of the East Antarctic Ice Sheet lie on pre-glacial sedimentary basins containing around 21,000 billion tonnes of carbon, said the scientists, writing in the journal Nature. British co-author Professor Jemma Wadham, from the University of Bristol, said: “This is an immense amount of organic carbon, more than 10 times the size of carbon stocks in northern permafrost regions. “Our laboratory experiments tell us that these sub-ice environments are also biologically active, meaning that this organic carbon is probably being metabolised into carbon dioxide and methane gas by microbes.” The amount of frozen and free methane gas beneath the ice sheets could amount to four billion tonnes, the researchers estimate. Disappearing ice could free enough of the gas to have an impact on future global climate change, they believe. “Our study highlights the need for continued scientific exploration of remote sub-ice environments in Antarctica because they may have far greater impact on earth’s climate system than we have appreciated in the past,” said Prof Tulaczyk. The Antarctic ice sheet covers the southern continent’s land-mass and not the sea around it. Methane hydrates — a combination of frozen water ice and methane — are also found at the bottom of the oceans where they form as a result of cold temperatures and high pressures. — The Independent
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THIS UNIVERSE How do flies float in the air unaffected by the movement of a bus? I think you are trying to discover something very deep in a situation that should be self-evident. When you have a bus with all its windows closed, the air in the bus is traveling with it. Whether you have a fly floating in the middle or a small balloon floating, they will not be conscious of the fact that the bus is travelling on a smooth road at 70 km an hour or more. Indeed, you think of a fly in an aeroplane flying at a thousand kilometers per hour and it will be no more aware of the great speed at which it is moving than a person sitting in a comfortable seat. It is useful to think of us all and the flies we see around going on a continuous journey of thousands of kilometers an hour while sitting on a chair in our garden — we have to remember that our chair, the garden, and the lawn around are all moving, along with the air that surrounds us. Let me also remind you in that example of the fly in the bus that when the fly happens to come near a partially or fully open window, it is quickly swept away. I am sure you can yourself think of many circumstances and happenings that will assure you that I am not talking non-sense. Readers wanting to ask Prof Yash Pal a question can e-mail him at palyash.pal@gmail.com
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Newly discovered dust-obscured galaxies may be missing link
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THE latest news from the Arctic cirlce should be, environmental campaigners say, a global wake-up call. The ice cap covering the top of the world is now smaller than it has been at any point since scientists started to measure it precisely from space.
