The Earth’s protective ozone layer is well on track to recovery in the next few decades thanks to concerted international action against ozone depleting substances, the latest assessment by scientists across the world has said.
According to the assessment, carried out by the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO), without the Montreal Protocol and associated agreements atmospheric levels of ozone depleting substances could have increased tenfold by 2050.
There have in fact been decreases in atmospheric abundance of gases such as chlorofluorocarbons (CFCs) and halons, which are used in refrigerators, spray cans, insulation foam and fire suppression. The full report will be issued in early 2015.
The Scientific Assessment of Ozone Depletion, 2014 was prepared and reviewed by 282 scientists from 36 countries. In 1987, ozone-depleting substances contributed about 10 gigatonnes CO2-equivalent emissions per year.
The Montreal Protocol, which was adopted that year with the aim of reducing ozone depleting substances, has been successful in reducing these emissions by more than 90 per cent. This decrease is about five times larger than the annual emissions reduction target for the first commitment period (2008-2012) of the Kyoto Protocol.
According to global models, the Protocol will have prevented 2 million annual cases of skin cancer by 2030, averted damage to human eyes and immune systems, and protected wildlife and agriculture.
This is the first comprehensive update in four years, and the summary document says the phase-out of ozone depleting substances has had a positive spin-off for the global climate because many of these substances are also potent greenhouse gases.
However, the report cautions that the rapid increase in certain substitutes, which are themselves also potent greenhouse gases, has the potential to undermine these gains.
It also notes that there are possible approaches to avoiding the harmful climate effects of these substitutes.
“However, the challenges that we face are still huge. The Montreal Protocol community, with its tangible achievements, is in a position to provide strong evidence that global cooperation and concerted action are the key ingredients to secure the protection of our global commons,” said U.N. Under-Secretary-General and UNEP Executive Director Achim Steiner said.
“International action on the ozone layer is a major environmental success story,” said WMO Secretary-General Michel Jarraud.
Book review: >Environmental protection — Protecting the ozone layer — The United Nations History
