The ozone layer is regenerating, and could be back up to strength by the middle of the century, according to a UN report.
It concludes that international efforts such as the Montreal Protocol are successfully protecting the ozone layer, which protects life on Earth from harmful levels of ultraviolet rays.
The report, titled Scientific Assessment of Ozone Depletion 2010, was written and reviewed by around 300 scientists and is the first comprehensive update in four years.
The Montreal Protocol, it says, is working. "It has protected the stratospheric ozone layer from much higher levels of depletion by phasing out production and consumption of ozone depleting substances," says the report. Almost 100 substances once used in refrigerators, aerosols and other products have been phased out.
"Without the Montreal Protocol and its associated Vienna Convention atmospheric levels of ozone-depleting substances could have increased tenfold by 2050," said Achim Steiner, UN under-secretary general and UNEP executive director.
"This in turn could have led to up to 20 million more cases of skin cancer and 130 million more cases of eye cataracts, not to speak of damage to human immune systems, wildlife and agriculture."
Given that many substances that deplete the ozone layer are also
potent greenhouse gases, the report says that the Montreal Protocol
has "provided substantial co-benefits by reducing climate change."
In 2010, the Protocol led to a reduction of ozone-depleting
substances that was five times larger than the 2008-2012 reduction
resulting from the Kyoto Protocol, the greenhouse emissions reduction
The report says that an important challenge which still remains is to
examine the complex linkages between ozone and climate change.
Changes in climate are expected to have an increasing influence on
stratospheric ozone in the coming decades, it says. The changes
derive mainly from the emissions of long-lived greenhouse gases,
mainly carbon dioxide, associated with human activities.