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Arctic ozone hole causes concern

Stratospheric ozone loss in the Arctic has this year reached a level never observed before in the northern hemisphere.

Observations made since January from the ground and from balloons show that 40% of ozone molecules have been destroyed over the Arctic. The highest ozone loss previously measured in early spring, when ozone depletion reaches its maximum, was 30% in 2005. Nature first reported on this last month.

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Scientists with the World Meteorological Organisation and the Alfred Wegener Institute of Polar and Marine Research (AWI) released the figures today at the general assembly of the European Union of Geosciences in Vienna.

There was a palpable sense in the EGU press room that the Arctic has indeed experienced its first-ever full-fledged ozone hole – massive ozone loss previously only observed over colder Antarctica.

“It’s a fair question to ask if there’s any difference left between seasonal ozone depletion in the Arctic and in Antarctica,” says Markus Rex, an ozone researcher with AWI.


“It’s unprecedented, but not totally unexpected,” says Geir Braathen of the WMO’s atmospheric environmental research division.

The main reason for the record ozone loss this year is that unusually cold stratospheric temperatures, extending until late in the season, have favoured the formation of polar stratospheric clouds. The catalytic chemical destruction of ozone molecules occurs on the surface of these clouds which form at 18-25 kilometres height when temperatures drop below -78 C.

Ozone-depleted air has in the past few weeks reached Scandinavia and northern China. More densely populated areas in Europe, Asia and North America have been spared so far, but an excursion of ozone-depleted air to mid-latitudes could still happen any time in the next two weeks or so.

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The stratospheric ozone layer absorbs the bulk of harmful UV-B radiation reaching the Earth. Current conditions mean that, unprotected, people might get sunburned in 20-30 minutes.

“It’s not dramatic, but people do need to know this,” says Rex.

The phasing out of ozone-destroying chemicals since 1987 has so far merely led to an average 10% or so recovery of the polar ozone layers. Stratospheric ozone is not expected to fully recover to 1980 levels before the end of the century.

Image 1: CRNS. Image 2: Location of Arctic polar vortex on April 4, 2011 / AWI

Comments

  1. Report this comment

    Caw Mentor said:

    The hole exists, because the ozone is being forced out of the area by the cold air.

    Ozone O3 is a 3 piece oxygen molecule created by a reaction of sunlight and oxygen in the atmosphere. It is always being created anywhere the sun hits the air, and destroyed by the UV light.

    In the antarctic the ice is so thick that a polar vortex always forms during their long night of winter ( a month or so with no sunlight at all.) during that time the cold air pushes all the warm air out and forms almost a wall of cold.

    Because the Ozone is formed by sunlight it is warm when created, so is also pushed out. It’s dark during the arctic winter so no Ozone is created there during that time so a hole forms.

    Now normally because there is no land mass at the North pole, and very little inside the arctic circle, there is not normally enough ice mass to set up a polar vortex there, but this year it was unusually cold. A vortex formed and then so did an Ozone hole.

    In both the arctic and the antarctic the ozone hole collapses once the sun rises again and heats the air enough to break the vortex.

    There is a risk though for maybe a few weeks that this cold air mass before it breaks up does not have the ozone levels in it to guard against UV radiation in these very northern cities and towns and they could be at risk to skin cancer from the elevated UV.

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    Edward C. De Fabo said:

    Once again Mr. Schiermeier gives us an important article on stratospheric ozone depletion in that it raises the awareness that ozone depletion is still with us and, indeed, is encroaching further over populated areas. Unfortunately, many have been lulled into a false sense of security that this phenomenon is long gone and one gets the impression that stratospheric ozone loss is not really that important-to wit the focus on sunburn in many recent press reports and blogs addressing current northern ozone depletion. This is not to downplay sunburn. If one receives enough solar UVB radiation to get sunburned, skin damage has already begun which could be important in melanoma and non-melanoma skin cancer formation. Rather, I point out that not all that much “extra” UVB may be needed to cause many other potentially harmful changes to human health, changes which get little or no mention. The types of potential health damage one might expect were detailed in a report I wrote for the International Journal of Circumpolar Health in 2005 http://www.ncbi.nlm.nih.gov/pubmed/16440613. Indeed, 5 years before in the same Journal I called for a vigorous research program precisely addressing neglected UVB impacts modeled after the decade-long projects for both the International Arctic Science Committee (IASC) and for the Scientific Committee On Problems of the Environment (SCOPE) which I chaired (1991-2000). These projects, developed by select teams of international experts in the relevant fields, addressed the need for a global research program to address specifically UVB effects on health and the environment and especially addressed a critical need for UVB dose-response studies. UVB radiation can cause many different biological, biochemical and biophysical effects that to give these changes short shrift by focusing on sunburn, is doing so at everyone’s peril.

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    Jukka Nukainen said:

    If that continues with the same speed as it does, in the next 20-30 years every living thing in northern part of the globe will be fried alive when going outside.

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