Ozone treaty is delaying first ice-free Arctic summer

Newswise — Fresh research indicates that a 1987 worldwide agreement aimed at safeguarding the ozone layer is postponing the advent of the initial ice-free Arctic summer by approximately 15 years.

The Montreal Protocol, the primary accord ratified by every UN nation, governs around 100 artificial chemicals known as ozone-depleting substances (ODSs).

Although the primary objective was to preserve the ozone layer, it is worth noting that ODSs, in addition to their ozone-depleting properties, also act as potent greenhouse gases. As a result, the agreement has contributed to a deceleration in global warming.

According to the recent study, the consequences of this accord include a potential delay of up to 15 years in the occurrence of the first ice-free Arctic summer, which is currently projected to happen in the middle of this century. The extent of this delay is contingent upon future emissions.

The team of researchers, comprised of experts from UC Santa Cruz, Columbia University, and the University of Exeter, has estimated that for every 1,000 tonnes of ODS emissions prevented, approximately seven square kilometers of Arctic sea ice can be preserved.

Dr. Mark England, a senior research fellow at the University of Exeter and the Royal Commission for the Exhibition of 1851, emphasized that although ODSs may not be as prevalent as other greenhouse gases like carbon dioxide, they still have a substantial influence on global warming.

"ODSs exhibit notably robust impacts in the Arctic region, and they have played a significant role in propelling climate change in the Arctic during the latter half of the 20th century.

"While the cessation of these effects was not the primary objective of the Montreal Protocol, it has proven to be a remarkable serendipitous outcome."

Dr. England highlighted that opponents of the protocol had predicted various adverse consequences, many of which did not materialize. Instead, there is a multitude of documented instances showcasing unintended climate benefits resulting from the protocol.

Professor Lorenzo Polvani from Columbia University emphasized that the occurrence of the first ice-free Arctic summer, which signifies a significant reduction of sea ice in the Arctic Ocean, will be a pivotal milestone in the progression of climate change.

"Our findings unequivocally illustrate the significant impact of the Montreal Protocol as a highly effective treaty for climate protection. It has achieved far beyond its original purpose of healing the ozone hole over the South Pole."

“Its effects are being felt all over the world, especially in the Arctic.”

ODS decline

The study, employing novel climate model simulations, reveals that the preservation of the ozone layer did not directly contribute to the mitigation of Arctic sea ice loss. Instead, all the benefits observed can be attributed to the role of ODSs as greenhouse gases.

ODSs, including chlorofluorocarbons (CFCs), are compounds that were developed in the previous century for industrial applications such as refrigerants and propellants.

The Montreal Protocol, which has been ratified by all 198 United Nations member states, implemented regulations for these compounds to safeguard the ozone layer. This protective layer shields humans and the environment from excessive levels of ultraviolet radiation, which can be detrimental.

This collective endeavor has achieved success, as atmospheric concentrations of ODSs have been declining since the mid-1990s. There are promising indications that the ozone layer has begun to heal as a result.

Nonetheless, research has indicated a slight increase in ODS concentrations between 2010 and 2020. Therefore, Dr. England emphasized the importance of remaining vigilant and maintaining ongoing efforts to address this issue.

The study was funded by the US National Science Foundation.

The paper, titled "The Montreal Protocol is delaying the occurrence of the first ice-free Arctic summer," has been published in the journal Proceedings of the National Academy of Sciences.