Rebuilding the ozone layer

International Ozone Day on 16 September this year marked the 20th anniversary of the Montreal Protocol on Substances that Deplete the Ozone Layer — arguably the world’s most successful multilateral environmental agreement.

The Montreal Protocol limits the production and release of certain human-made substances that trigger damage to the protective blanket of ozone in the stratosphere (10–50km above the Earth’s surface).

Over the past 30 years the action of such chemicals and the special meteorological conditions found in the winter polar stratosphere, particularly over Antarctica, have resulted in dramatic episodes of enhanced ozone destruction during spring — and the formation of the ‘ozone hole’. The scientific study of this phenomenon in the 1980s provided the basis for the swift cooperative action that lead to the Montreal Protocol.

After 20 years of international action there has been a 95% reduction in global emissions of ozone depleting substances and there are initial indications of ozone recovery in certain parts of the atmosphere. However, the international scientific community is still intensively examining human influences on ozone to ensure that we can accurately assess the state of the atmosphere and the effectiveness of our actions.

During this, the International Polar Year (IPY), the ‘ORACLE-O3’ project (also know as ‘Ozone layer and UV radiation in a changing climate evaluated during IPY’) will conduct extensive measurement and modelling studies of ozone in the Antarctic and Arctic (Australian Antarctic Magazine 12: 12–13). The Antarctic measurements include a network of nine stations that are measuring the vertical distribution of ozone with balloons — with Australia’s Davis station contributing ozone and other atmospheric measurements to the project.

ANDREW KLEKOCIUK, Ice, Ocean, Atmosphere and Climate programme, AAD
MANDY McKENDRICK, Information Services, AAD