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.”


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
[5] Regular NASA images of the Antarctic ozone hole:

NASA – A year in the life of Earth’s carbon dioxide

An ultra-high-resolution NASA computer model has given scientists a stunning new look at how carbon dioxide in the atmosphere travels around the globe.

Plumes of carbon dioxide in the simulation shift and swirl as winds disperse the greenhouse gas away from its sources, which are dominated by North American, European and East Asian centres.

The simulation also illustrates differences in carbon dioxide levels in the northern and southern hemispheres and distinct swings in global carbon dioxide concentrations as the growth cycle of plants and trees changes with the seasons.

The carbon dioxide visualisation was produced by a computer model called GEOS-5, created by scientists at NASA Goddard Space Flight Center’s Global Modeling and Assimilation Office.

How can we weigh a cloud?

JimCGS air quality expert Dr Jim McQuaid has been filming a BBC two-part documentary Operation Cloud Lab: Secrets of the Skies. The documentary follows a team of scientists as they explore the earth’s atmosphere, travelling in an airship. The expedition begins with an examination of clouds and how we can determine the weight of an average cloud.You might be surprised at the result!

You can watch the first episode on BBC iplayer.



How polluted is the air you’re breathing?


The Atlantic has recently published a global map of air quality. Take a look at the interactive map to find out how the quality of the air you’re breathing compares with other countries and cities.The news isn’t good if you’re in China, India, Nepal, Pakistan, and Bangladesh.

The map overlays two sources of data on air pollution: for cities, the World Health Organization’s ambient (outdoor) air pollution in cities database 2014; for countries, ground-level exposures to fine particulate matter (PM2.5) are derived from satellite measures used in the 2014 Environmental Performance Index, a biennial global ranking produced by Yale and Columbia researchers that compares countries on high-priority environmental issues.


More information:
[1] See the interactive on the Atlantic website at
[2] Read more about global air quality at
[3] Read more about PM2.5 at
[4] Find out more about the Environmental Performance Index at