Reading this press release about a new paper in Palaeogeography, Palaeoclimatology, Palaeoecology spoiled my day. It might not be obvious to a casual reader just glancing through the morning news — but a couple of paragraphs leapt out at me:
Atmospheric carbon dioxide concentrations recently reached 400 parts per million for the first time since the Pliocene Epoch, three million years ago. During this era, Arctic surface temperatures were 15-20 degrees Celsius warmer than today’s surface temperatures.
Ballantyne’s findings suggest that much of the surface warming likely was due to ice-free conditions in the Arctic. That finding matches estimates of land temperatures in the Arctic during the same time. This suggests that atmospheric carbon dioxide concentrations of 400 ppm may be sufficient to greatly reduce the spatial extent and seasonal persistence of Arctic sea ice.
In other words, losing Arctic sea ice brings huge warming to the lands around the Arctic Ocean. This is extremely bad news for a number of reasons:
Continue reading “Arctic sea ice time bomb ticking: the bang’s gonna be huge”
In this guest post Neven Acropolis, the man behind the excellent Arctic Sea Ice blog, looks at the reasons why we need to pay attention to the rapid loss of sea ice in the Arctic Ocean.
Arctic sea ice became a recurrent feature on planet Earth around 47 million years ago. Since the start of the current ice age, about 2.5 million years ago, the Arctic Ocean has been completely covered with sea ice. Only during interglacials, like the one we are in now, does some of the sea ice melt during summer, when the top of the planet is oriented a bit more towards the Sun and receives large amounts of sunlight for several summer months. Even then, when winter starts, the ice-free portion of the Arctic Ocean freezes over again with a new layer of sea ice.
Since the dawn of human civilisation, 5000 to 8000 years ago, this annual ebb and flow of melting and freezing Arctic sea ice has been more or less consistent. There were periods when more ice melted during summer, and periods when less melted. However, a radical shift has occurred in recent times.
Ever since satellites allowed a detailed view of the Arctic and its ice, a pronounced decrease in summer sea ice cover has been observed (with this year setting a new record low). When the IPCC released its Fourth Assessment Report in 2007, it was generally thought that the Arctic could become ice-free somewhere near the end of this century. But changes in the Arctic have progressed at such speed that most experts now think 2030 might see an ice-free Arctic for the first time. Some say it could even happen this decade.
What makes this event significant, is the role Arctic sea ice plays as a reflector of solar energy. Ice is white and therefore reflects a large part of incoming sunlight back out to space. But where there is no ice, dark ocean water absorbs most of the sunlight and thus heats up. The less ice there is, the more the water heats up, melting more ice. This feedback has all kinds of consequences for the Arctic region.
Continue reading “Why Arctic sea ice shouldn’t leave anyone cold”
Grab some holly, deck your halls, heat up some mince pies, and then settle down to the last Climate Show of 2011. We look at the outcome of the Durban conference, discuss heavy rain in New Zealand and record-breaking weather extremes in the USA, and ponder the implications of news of more methane erupting from the seabed off Siberia. Glenn interviews Chris Paine, director of EV documentary Revenge of the Electric Car, and we round off the show with some optimistic news on possible energy solutions.
Watch The Climate Show on our Youtube channel, subscribe to the podcast via iTunes, listen to us via Stitcher on your smartphone or listen direct/download from the link below the fold…
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Continue reading “The Climate Show #23: Durban and the return of the electric car”
The latest estimate of methane release from the shallow seas off the north coast of Russia — the East Siberian Arctic Shelf (ESAS) — suggests that around 8 teragrams per year (1Tg = 1 million tonnes) of the gas are reaching the atmosphere. This is equivalent to previous estimates of total methane release from all oceans. The study, led by Natalia Shakhova and Igor Semiletov and published in this week’s Science (Extensive Methane Venting to the Atmosphere from Sediments of the East Siberian Arctic Shelf, Science 5 March 2010, Vol. 327. no. 5970, pp. 1246 – 1250 DOI: 10.1126/science.1182221), is based on fieldwork over 2003 – 2008. Over 80% of the bottom water over the ESAS was found to be supersaturated with dissolved methane, and 50% of the surface water. More than 100 “hotspots’ were discovered, where large quantities of methane are escaping from the sea-floor. Here’s Shakhova discussing the paper’s findings in a University of Alaska Fairbanks video (press release):
Continue reading “Siberian seabed methane: first numbers”
Methane release from the permafrost and hydrates under the East Siberian Shelf in autumn 2009 was the highest ever recorded, the leader of the International Siberian Shelf Study (ISSS), Igor Semiletov, has told the BBC. The results of last autumn’s research cruises are being prepared for publication in the near future. The BBC also quotes Semiletov’s colleague Prof Orjan Gustafsson from Stockholm University:
He said that methane measured in the atmosphere around the region is 100 times higher than normal background levels, and in some cases 1,000 times higher.
Gustaffson went on to say that “so far” there was no cause for alarm, and stressed the need for further study. Sounds like a scientist… For background, check out last year’s WWF Arctic report (I discussed the chapter on Arctic methane here), and my posts on the 2008 ISSS expeditions (one, two). Looks like the methane release is confirmed as chronic, but not yet (if we’re lucky) acute.