Ozone hole over Canadian Arctic — twice the size of Ontario

Scientist speaks out after finding ‘record’ ozone hole over Canadian Arctic | News | National Post: "

OTTAWA — A senior Environment Canada scientist... has highlighted the importance of maintaining the country’s world-leading atmospheric monitoring network after new research showed a record hole in the planet’s ozone layer above the Arctic.

David Tarasick was among four Canadian authors of the international study, published Oct. 2 in the British scientific journal Nature, that reported on the hole — twice the size of Ontario — in the ozone layer that protects life on Earth from the sun’s harmful radiation."

“We’ve been doing this [for] about 45 years now,” Tarasick said in a telephone interview supervised by Environment Canada officials. “The Canadian stations have been the backbone of the global network [of monitoring] ever since we started measuring ozone.”

Tarasick explained that the monitoring network already has “limited resources” for maintaining the existing quality of data collected and used in the recent Nature study.

 He explained that the monitoring work has numerous implications regarding issues such as pollution, as well as weather forecasting.

“Ozone is very important in many ways,” he said. “In effect, it determines the large-scale circulation of the atmosphere. We didn’t start measuring ozone because we were worried about ozone depletion. We started measuring ozone back in the 1950s because we were trying to understand the circulation of the atmosphere better and to improve weather forecasting . . . and it was fortunate that we had a long data set when people started to notice that the ozone was changing.”

Ozone is considered to be a pollutant that affects air quality in the lower atmosphere, but in the upper atmosphere, it acts as a shield for life on Earth from the sun’s ultraviolet radiation.

According to computer models, it could take 10 to 40 years for the ozone layer to recover from depletion caused by substances released prior to an international agreement — signed in 1987 in Montreal — to phase them out of products such as spray cans and refrigerators. Scientists say there is uncertainty in the predictions partly because of the ongoing release of some ozone-depleting substances that can be tracked through the existing monitoring and measurements.

“It’s really a global problem, which is why there is so much interest in our data from around the world,” said Tarasick. “To be trite, the atmosphere is a global atmosphere.”

Meantime, Tarasick said the Nature study also discusses some uncertainties in existing models about global warming in the Arctic. He also noted other research that shows how the increasing concentration of greenhouse gas emissions in the atmosphere is trapping heat in the lower part, and resulting in cooling temperatures in the upper atmosphere, which can contribute to ozone depletion.

Environment Canada measurements show that the hole over the Arctic resulted in somewhat lower ozone over most Canadians this summer, and UV levels about three to five per cent higher than what would be expected if there had not been a hole. Canadians should not have health concerns because of the recent ozone depletion.

Postmedia News
mdesouza@postmedia.com

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