Patching up the ozone hole: The success of the Montreal Protocol

New model results show that the Antarctic ozone hole would have grown in size by 40% by 2013 if ozone depleting chemicals had not been banned in the 1980s.

CGS researchers at the University of Leeds’ School of Earth and Environment used computer models to determine the impacts of ozone damaging substances (ODSs) on the Earth’s ozone layer. They show that international efforts to control the release of ODSs has had a significant and measurable impact on reducing the size of the hole in the ozone layer.

The results from the study are published in Nature Communications.

Arctic ozone without the Montreal Protocol (left) and following its implementation (right).

Arctic ozone without the Montreal Protocol (left) and following its implementation (right).

The Montreal Protocol is regarded as one of the most important global treaties in history. The protocol was signed in 1987 with the aim to control the international use of ozone damaging substances. Without it, the researchers reveal that not only would the ozone hole over Antarctic be much bigger now but there would also be a significant hole over the Arctic region. The Arctic hole would have been large enough to affect much of northern Europe, including the UK. This ozone loss would have led to increases in surface ultraviolet radiation of up to 14% in the United Kingdom with a consequent increase in skin cancer and other related skin illnesses.

The new research simulated what the ozone hole would have been like today if nothing had been done. Lead researcher, Professor Martyn Chipperfield told the BBC: ”We would be living in an era of having regular Arctic ozone holes.”

Background

The ozone layer is a region of the Earth’s atmosphere that absorbs most of the sun’s harmful ultraviolet radiation. It contains higher amounts of ozone (O3) compared other parts of the atmosphere, hence the name.

False-color view of total ozone over the Antarctic pole. The purple and blue colors are where there is the least ozone, and the yellows and reds are where there is more ozone.  Source: NASA

False-color view of total ozone over the Antarctic pole on 23rd May 2015. The purple and blue colours are where there is the least ozone, and the yellows and reds are where there is more ozone.
Source: NASA

In the late 1970s scientists began to notice large holes appearing within the ozone layer over the Antarctic. The discovery of the annual depletion of ozone above the Antarctic was first announced by scientists at the British Antarctic Survey, in a paper which appeared in Nature, 1985. The cause of the depletion was linked to the use of chlorine, bromine and other chemical gases reaching the atmosphere. These were thought to be released from the extensive use of chlorofluorocarbons (CFCs) in business and industry during the 60s and 70s.

The discovery of the Antarctic ozone hole helped stimulate the signing in 1987 of the Montreal Protocol, an international treaty to limit production of chlorine-and bromine-containing ozone depleting substances.

The study concludes that, since the signing and enforcement of the Montreal Protocol levels of chlorine and bromine containing ozone depleting chemicals in the atmosphere have peaked and then declined. And this has resulted in a steady recovery of the holes in the ozone layer over the past two decades.

More information:

[1] Quantifying the ozone and ultraviolet benefits already achieved by the Montreal Protocol, Nature 2015
[2] CGS and Leeds researchers involved in the study:
Professor Martyn Chipperfield
Dr Sandip Dhomse
[3] http://www.nature.com/nature/journal/v315/n6016/abs/315207a0.html
[4] http://ozone.unep.org/new_site/en/montreal_protocol.php
[5] Regular NASA images of the Antarctic ozone hole: http://ozonewatch.gsfc.nasa.gov/

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