Depletion of the ozone layer over the Arctic has reached record levels, the UN weather agency according to WMO, blaming harmful substances in the atmosphere and a very cold winter.
The Arctic ozone layer suffered a loss of about 40 per cent from the beginning of winter to late March, up from the previous record of about 30 per cent over the entire winter, according to the World Meteorological Organisation.
“Depletion of the ozone layer – the shield that protects life on earth from harmful levels of ultraviolet rays – 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.
Meanwhile, 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 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 8,400 cubic kilometres. That is the equivalent of all the water in Lake Michigan and Lake Huron in the US or double the volume of water in Lake Victoria, Africa’s largest lake.
Increased run-off 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 Dr 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 Ms De Steur and Mr 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 as part of a European Union initiative, called Clamer, to collate and publicise information from 300 EU-funded research projects conducted over the last 13 years on climate change and marine ecology.
Mr 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 run-off on ocean salinity.
Dr 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.