Should we still be concerned about the ozone layer?

In 1985 Scientists who were a part of the British Antarctic Survey published results showing that there was a hole in the ozone layer above the Antarctic shocking the scientific community as the decline was far higher than anticipated. In a rare case of quick action to an environmental threat, later that year nations agreed in Vienna to take "appropriate measures...to protect human health and the environment against adverse effects resulting or likely to result from human activities which modify or are likely to modify the Ozone Layer" and in 1987 in Montreal CFCs were banned, to be phased out by 2000. As a result of this the ozone layer is beginning to recover so should we still be concerned about it?

Should we still be concerned about the ozone layer?

Yes because... No because...

CFCs may be banned but there are other chemicals that destroy the ozone layer.

CFCs may well be the best known threat to the ozone layer but they are not the only threat. We can’t be complacent thinking that we have solved the problem when that may not be the case. Nitrous oxide (N2O) is now a threat to the ozone layer. As Nitrous oxide has been pretty much ignored by policy makers the use of nitrous oxide has been rising.

if nitrous oxide emissions are not reduced, they could be 30% more destructive to ozone in 2050 than the combined CFC emissions from 1987, when these were at their peak

Unfortunately Nitrous oxide was not included with other ozone depleting chemicals like CFCs in the international treaties banning their use. Instead it has been classified with greenhouse gasses, the regulation of which is so far not going anywhere fast.[[Lizzie Buchen, Ozone threat is no laughing matter; Nitrous oxide poses a growing atmospheric problem, Nature, 27/8.09, http://www.nature.com/news/2009/090827/full/news.2009.858.html

We have however always known the Nitrous oxide destroys ozone.

Richard Stolarski NASA's Goddard Space Flight Center

"Nitrous oxide sort of died out as a problem [for the ozone layer] in the 1970s, because we knew it was increasing at such a slow rate,... In our chemical climate models, where nitrous oxide increases by 15 or 20 per cent by 2100, we still end up with more ozone than we had in 1960 [before mass production of CFCs]."

[[Lizzie Buchen, Ozone threat is no laughing matter; Nitrous oxide poses a growing atmospheric problem, Nature, 27/8.09, http://www.nature.com/news/2009/090827/full/news.2009.858.ht ] the ozone layer has started to repair itself due to peoples common sense at last , the planting of trees and the less use of aerosols is starting to work, there has been a great improvement in the ozone layer areas.]

Should we still be concerned about the ozone layer?

Yes because... No because...

The largest ‘hole’ in the ozone layer is recent

While the Montreal Protocol banned chlorofluorocarbons (CFCs), halons, carbon tetrachloride, and methyl chloroform way back in 1987 the ozone hole continued to grow. The largest ever whole in the Ozone layer was on the 24th September 2006.[[http://ozonewatch.gsfc.nasa.gov/]] Scientists also admit that

Daniel L. Albritton director of the NOAA Aeronomy Laboratory

We expect to see year-to-year variations in the size of the ozone hole, because stratospheric temperatures can vary from year to year. In colder years, the same amount of ozone-depleting compounds can destroy more ozone, in comparison to warmer years.

[[National Oceanic and Atmospheric Administration, Antarctic Ozone Hole at Near Record Size This Year, Times Higher Education, 9/10/03, http://www.timeshighereducation.co.uk/story.asp?storyCode=184121&sectioncode=26 this makes it difficult to see how quickly the whole is repairing.

This increase in the size of the ozone hole after the signing of the Protocol is only because there was a long period during which countries could phase out using CFCs. CFC were therefore only banned in 2000 and the less damaging HCFCs (Hydrochlorofluorocarbons) are targeted for phasing out by 2040 they are still being used, often as a replacement for CFCs. Not surprisingly the production and use of HCFCs has increased over the last couple of decades.[[http://www.undp.org/chemicals/montrealprotocol.htm]] none the less as they are being banned in the future this is no longer a problem as the ozone hole will begin to repair in response. We could not expect to see there being much of a change while we were/are still producing these damaging chemicals. At the same time the chemicals we have already produced remain a problem.

James Laver, Director of NOAA's Climate Prediction Center

Although international protocols have greatly reduced the production and release of ozone depleting chemicals, they will remain active in the stratosphere for several decades.

[[National Oceanic and Atmospheric Administration, Antarctic Ozone Hole at Near Record Size This Year, Times Higher Education, 9/10/03, http://www.timeshighereducation.co.uk/story.asp?storyCode=184121&sectioncode=26

Should we still be concerned about the ozone layer?

Yes because... No because...

Not a political issue.

There is no debate about the need to repair the ozone layer, the debate is done and dusted and has political support. 196 countries have ratified the Montreal Protocol and almost as many have ratified its amendments at London (1990: 195 countries), Copenhagen (1992: 192), Montreal (1997: 181) and Beijing (1999: 164) [[http://ozone.unep.org/Ratification_status/]] implying that it would not be a problem to include new things into the protocol if necessary. The ozone layer does not matter because any problems with will be dealt with unlike for example tackling CO2 emissions.

Should we still be concerned about the ozone layer?

Yes because... No because...

The ozone hole is getting smaller.

The shrinking of the hole in the ozone layer may not be due to an overall recovery. In 2007 it was reported that there was a smaller hole in the ozone layer over the Antarctic than there had often been in the last couple of decades, especially compared to the biggest hole in 2006. The ozone loss in 2007 peaked at 27.7 million tonnes, compared to the 2006 ozone loss of 40 million tonnes. However this was due to mild temperatures in the stratosphere during the Antarctic winter. However unlike at ground level as greenhouse gases accumulate in the atmosphere, temperatures will fall in the stratosphere, increasing the threat of severe ozone holes in the future.[[Antarctic Ozone Hole Shrinking Because Of Mild Weather, Not Recovery, ScienceDaily, 22/10/07, http://www.sciencedaily.com/releases/2007/10/071021114804.htm This means that any reports that the holes in the ozone are no longer a concern need to be treated with scepticism.

In 2006 the hole in the ozone layer was 27.5 million km2[[http://earthobservatory.nasa.gov/IOTD/view.php?id=7044]], in 2007 it was 25million km2, in 2008 it went back up to 27 million and in 2009 it was similar to its 2007 size.[[ Ozone hole smaller in 2009 than 2008: WMO, Physorg.com 16/9/09, http://www.physorg.com/news172311361.html Although there is some variation the hole is beginning to close. Scientists predict that it could be closed by 2050.[[Ozone hole ‘set to shrink’, BBC News, 3/12/00, http://news.bbc.co.uk/1/hi/sci/tech/1050495.stm

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