Record depletion of ozone recorded over Arctic: UN
Stephanie Nebehay, Reuters · Apr. 5, 2011
GENEVA — Record loss of the ozone, the atmosphere layer that shields life from the sun’s harmful rays, has been observed over the Arctic in recent months, the World Meteorological Organization said on Tuesday.
"Depletion of the ozone...has reached an unprecedented level over the Arctic this spring because of the continuing presence of ozone-depleting substances in the atmosphere and a very cold winter in the stratosphere," the WMO said in a statement.
Observations from the ground, balloons and satellites show that the region has suffered an ozone column loss of about 40 percent from the beginning of the winter to late March, according to the United Nations agency.
The highest ozone loss previously recorded over the Arctic, about 30 percent, occured in several seasons over the past 15 years or so, according to a WMO spokeswoman.
"If the ozone depleted area moves away from the pole and towards lower latitudes one can expect increased ultraviolet (UV) radiation as compared to the normal for the season," WMO said, adding that the public should check their national UV forecasts.
But any increase in UV radiation over lower latitudes away from the Arctic — which could affect parts of Canada, Nordic countries, Russia and Alaska in the United States — would not be of the same intensity as one suffers in the tropics, it said.
UV-B rays have been linked to skin cancer, cataracts and damage to the human immune system. "Some crops and forms of marine life can also suffer adverse effects," the agency said.
Unlike over Antarctica, large ozone loss is not an annually recurring phenomenon in the Arctic stratosphere, where meteorological conditions vary much more each year.
The record ozone loss over the Arctic comes despite the "very successful" Montreal Protocol aimed at cutting production and consumption of ozone-destroying chemicals such as chlorofluorocarbons (CFCs) and halons, the WMO said.
The substances were once present in refrigerators, spray cans and fire extinguishers, but have been phased out.
Nevertheless, due to the long lifetimes of these compounds in the atmosphere, it will take several decades before their concentrations return to pre-1980 levels, the target laid down in the 1987 pact, it said.
Scientists concerned massive pool of fresh water in Arctic Ocean could alter Atlantic currents
AMSTERDAM - Scientists are monitoring a massive pool of fresh water in the Arctic Ocean that could spill into the Atlantic and potentially alter the ocean currents that bring Western Europe its moderate climate.
The oceanographers said Tuesday the unusual accumulation has been caused by Siberian and Canadian rivers dumping more water into the Arctic, and from melting sea ice. Both are consequences of global warming.
If it flushes into the Atlantic, the infusion of fresh water could, in the worst case, change the ocean current that brings warmth from the tropics to European shores, said Laura De Steur, of the Royal Netherlands Institute for Sea Research.
German researcher Benjamin Rabe, of the Alfred Wegener Institute, said the Arctic’s fresh water content had increased 20 per cent since the 1990s, or by a 8,400 cubic kilometres. That is the equivalent of all the water contained in Lake Michigan and Lake Huron in the U.S. or double the volume of water in Lake Victoria, Africa’s largest lake.
Increased runoff from the great northern rivers “could potentially impact the large scale ocean circulation in the Atlantic Ocean. This is important for us in Western Europe because our climate is pretty much dictated by the Thermohaline ocean circulation,” said De Steur.
The Thermohaline current loops like a conveyer belt from the tropics to the North Atlantic, driven by the differences in salt content and wind patterns. Warm water from the south gains in salinity and grows heavier as it cools. At its northern end the current is further chilled by cold air and sinks, warming again and rising as it travels south.
That cycle could be affected when the pool of fresh water is released into the Atlantic, said De Steur and Rabe. The icy water has been kept bottled up in the Arctic by wind patterns, which have not shifted their general clockwise direction for the unusually long time of 12 years. Normally, the winds change at intervals of five to 10 years.
The two scientists spoke to The Associated Press as part of a European Union initiative, called Clamer, to collate and publicize information from 300 EU-funded research projects conducted over the last 13 years on climate change and marine ecology. Rabe and colleagues from the Alfred Wegener Institute in Bremerhaven, Germany, published their research last year in the journal Deep Sea Research on the effects of higher river runoff on ocean salinity.
De Steur said most of the excess fresh water has collected in the Canada Basin, but in the last three years changes also have been noticed in the Eurasian side of the Arctic Ocean.
“It’s important to monitor this to see if this can be transported to the Atlantic, where it might potentially effect the Gulf Stream and the Thermohaline circulation,” she said.
Rabe cautioned that scientists have not been studying the situation long enough to predict what may happen, and the results of model simulations also were inconclusive.
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