MOSCOW, September 11 (RIA Novosti) - The Earth's protective ozone layer may fully recover in the next few decades thanks to harmonized international action against ozone depleting substances, a new assessment by the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO) reads.

"There are positive indications that the ozone layer is on track to recovery towards the middle of the century. The Montreal Protocol - one of the world's most successful environmental treaties - has protected the stratospheric ozone layer and avoided enhanced UV radiation reaching the earth's surface," said UN Under-Secretary-General and UNEP Executive Director Achim Steiner in a press-statement Wednesday.

Scientific Assessment of Ozone Depletion 2014 carried out by 300 scientists has found out that actions taken under the Montreal Protocol are enabling the return of the ozone layer to benchmark 1980 levels, as they led to a significant decrease in substances causing greenhouse effect. Moreover, according to UNEP, the Protocol will have prevented 2 million cases of skin cancer annually by 2030, averted damage to human eyes and immune systems, and protected wildlife and agriculture.

However, the report also warns that the rapid increase in certain substitutes for these substances, which are themselves also potent greenhouse gases, has the potential to undermine the gains.

The stratospheric ozone layer is a fragile shield of gas that protects the Earth from harmful ultraviolet rays of the sun. The Montreal Protocol on Substances that Deplete the Ozone Layer is an international treaty designed to protect the ozone layer by phasing out the production of numerous substances that are responsible for its depletion.

The treaty entered into force in 1989 and is ratified by 196 countries, including Russia. Without the Montreal Protocol and associated agreements, atmospheric levels of ozone depleting substances could have increased tenfold by 2050, according to UNEP.