Archive for the ‘Arctic’ Category
According to a Reuters report published 29.10.2009, the multi-year ice covering the Arctic Ocean has effectively vanished.
The disappearance of Arctic multi-year ice is a disaster for polar ecosystems
This is important news for several reasons:
- *It is some of the best (or worst?) evidence yet of the rapidity and severity of Arctic warming (and by extension the globe).
*It is many years ahead of what modelers were predicting just a few short years ago.
*It potentially is the start of accelerated Arctic warming (runaway warming) due the loss of the albedo effect and activation of positive feedback loops (like permafrost thawing).
*It opens the Arctic up to shipping, exploration, drilling and other forms of environmentally-questionable activity.
The report describes how Canadian scientist David Barber (Research Chair in Arctic System Science at the University of Manitoba) went searching for multi-year pack ice and found very little. “We are almost out of multiyear sea ice in the northern hemisphere,” he said in a recent presentation to the Canadian Parliament.
Reuters says that Barber spoke shortly after returning from an expedition that sought (and largely failed to find) a huge multiyear ice pack that should have been in the Beaufort Sea off the Canadian coastal town of Tuktoyaktuk.
This type of ice can be tens of metres thick and to date has been the barrier closing the fabled Northwest Passage:
Vast sheets of impenetrable multiyear ice, which can reach up to 80 meters (260 feet) thick, have for centuries blocked the path of ships seeking a quick short cut through the fabled Northwest Passage from the Atlantic to the Pacific. They also ruled out the idea of sailing across the top of the world.
Barber also said that the Arctic is now, from a practical perspective, almost seasonally ice-free. The scale and rapidity of the changes astounded Barber. “I’ve never seen anything like this in my 30 years of working in the high Arctic … it was very dramatic,” he said.
An increasing number of experts feel the North Pole will be ice free in summer by 2030 at the latest, for the first time in a million years.
The Arctic is an early indicator of what we can expect at the global scale as we move through the next few decades … So we should be paying attention to this very carefully, according to Barber
Posted in The Arctic sea ice pack thawed to its third-lowest summer level on record – up slightly compared to the last two years but continuing an overall decline due to climate change.
Minimum extent was reached on 12 September (2009) when it covered just 5.1 million square kilometres. This falls 20 percent below the 30-year average minimum ice cover for the Arctic summer (since satellites began measuring in 1979), and 24 percent less than the 1979-2000 average.
This year’s minimum represents a loss of about two-thirds of the winter maximum (measured at the height of winter in March). In contrast, sea ice shrank by just over half each summer during the 1980s and 1990s.
Shrinking sea ice extent endangers polar bears and the entire Arctic ecosystem
The lowest summer minimum ever recorded was reached in September 2007, with the second lowest level reached last year. This year’s minimum comes in third lowest.
Even though this year’s minimum is higher than the last two years, it does not mean that global warming has stopped or reversed. Scientists expect fluctuations from year to year in many biological phenomena (including sea ice) – It is the direction and slope of the trend that is important, rather than any one year’s measurement.
Related: Arctic geese don’t fly south for winter.
An important research paper published earlier this month shows something that climate researchers have long feared – widespread release of methane from the Arctic sea-bed, due to warming currents.
There is a huge amount of methane contained in the Arctic sea floor as methane clathrates (CH4 trapped within water molecules) and deposited at the bottom of the region’s seas.
The clathrates remain stable at low temperatures, but as climate-change induced warming of northern ocean currents continues, scientists worry that methane could be liberated and released into the atmosphere.
As methane is a potent greenhouse gas (GHG), it is possible that runaway global warming (where positive environmental feedback loops lead to accelerated heating and spiralling liberation of GHG from methane clathrates, boreal permafrost, and other sources) could occur.
Once this happens it will be out of our power to stop the climate system from “tipping” to a significantly different, much hotter, state.
Sonar image of methane plumes rising from the Arctic Ocean floor (Image: National Oceanography Centre, Southampton)
Clathrates have been implicated in past environmental change, including the Permian extinction event -
WIKIPEDIA: The clathrate gun hypothesis is the popular name given to the hypothesis that rises in sea temperatures (and/or falls in sea level) can trigger the sudden release of methane from methane clathrate compounds buried in the seabeds and their permafrost, which, because the methane itself is a powerful greenhouse gas, in turn causes further temperature rise and further methane clathrate destabilization – in effect initiating a runaway process, as irreversible once started as the firing of a gun. There is strong evidence that runaway methane clathrate breakdown may have caused drastic alteration of the ocean environment and the atmosphere of earth on a number of occasions in the past…..most notably in connection with the Permian extinction event, when 96% of all marine species became extinct 251 million years ago.
The paper’s abstract says:
More than 250 plumes of gas bubbles have been discovered emanating from the seabed of the West Spitsbergen continental margin, in a depth range of 150–400 m, at and above the present upper limit of the gas hydrate stability zone (GHSZ). Some of the plumes extend upward to within 50 m of the sea surface. The gas is predominantly methane. Warming of the northward-flowing West Spitsbergen current by 1°C over the last thirty years is likely to have increased the release of methane from the seabed by reducing the extent of the GHSZ, causing the liberation of methane from decomposing hydrate. If this process becomes widespread along Arctic continental margins, tens of Teragrams of methane per year could be released into the ocean.
Read more about methane clathrates at New Scientist.
NASA Earth Observatory: Intense fires burning in the boreal forests of Russia, Alaska and Canada darkened Northern skies with smoke in July 2009. Large fires were burning in both Russia and Alaska in late July, and this image tracks the smoke from those fires by illustrating the concentration of carbon monoxide in the atmosphere.
Smoke from Fires in Russia and Alaska
CO Concentrations
Tundra fires are important for several reasons:
- About a third of the world’s soil-based carbon is locked-up in high-latitude tundra and boreal forest ecosystems.
- Burning tundra releases CO2 and destroys stored carbon (in organic matter) – one study estimates that 50 years of accumulated plant matter was lost after one severe fire.
- Severely burned tundra emits twice as much carbon as undamaged tundra normally stores away, for up to a year after burning.
- It also absorbs around 70 per cent more solar radiation, warming faster (due to blackening and loss of vegetative cover) – this causes thawing of the underlying permafrost (up to 10 centimetres deep).
- Thawing permafrost undergoes anaerobic decomposition and releases methane (a greenhouse gas 25 times more potent than CO2).
- This creates a positive feedback loop – burning and its later effects release carbon and melt permafrost. This causes more warming and makes further fires more likely.
- Tundra fires will become more frequent in future because higher temperatures and increasing dryness increase the amount of vegetation available to burn (by prompting a shift from tundra comprised mainly of small herbs and grasses to one dominated by larger shrubs).
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The image above was made with data collected by the Measurements of Pollution in the Troposphere (MOPITT) sensor on NASA’s Terra satellite between July 20 and July 26, 2009. Spots of red show where carbon monoxide concentrations were high, while orange areas point to moderate concentrations. Gray regions indicate places where no measurements were made, probably because of persistent clouds. The highest concentrations of carbon monoxide are centered over large fire complexes in Russia. Fires in Alaska were also pumping carbon monoxide into the atmosphere.
Carbon monoxide is a component of smoke that can be tracked long after the smoke has dispersed enough to no longer be visible. Carbon monoxide helps reveal where smoke’s other invisible fine particles and polluting gases end up. These invisible particles and gases, including carbon monoxide, are ingredients in the production of ground-level ozone, a harmful pollutant.
This article based on these two New Scientist articles:
Alaskas biggest tundra fire sparks climate warning.
Global warming may raise tundra wildfire risk.
