From the latest edition of Nature Magazine....

Chemical ozone destruction occurs over both polar regions in local winter–spring. In the Antarctic, essentially complete removal of lower-stratospheric ozone currently results in an ozone hole every year, whereas in the Arctic, ozone loss is highly variable and has until now been much more limited. Here we demonstrate that chemical ozone destruction over the Arctic in early 2011 was—for the first time in the observational record—comparable to that in the Antarctic ozone hole. Unusually long-lasting cold conditions in the Arctic lower stratosphere led to persistent enhancement in ozone-destroying forms of chlorine and to unprecedented ozone loss, which exceeded 80 per cent over 18–20 kilometres altitude. Our results show that Arctic ozone holes are possible even with temperatures much milder than those in the Antarctic. We cannot at present predict when such severe Arctic ozone depletion may be matched or exceeded.

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As alarming as that is, there is a Canadian back story.....

[...]

The hole covered two million square kilometres — about twice the size of Ontario — and allowed high levels of harmful ultraviolet radiation to hit large swaths of northern Canada, Europe and Russia this spring, the 29 scientists say.

The discovery of the “unprecedented” hole comes as the Canadian government is moving to cut its ozone monitoring network.

Environment Canada scientist David Tarasick, whose team played a key role in the report published Sunday in the journal Nature, is not being allowed to discuss the discovery with the media.

Environment Canada told Postmedia News that an interview with Tarasick “cannot be granted.” Tarasick is one of several Environment Canada ozone scientists who have received letters warning of possible “discontinuance of job function” as part of the downsizing underway in the department.

click link for complete article ‘Unprecedented’ ozone hole opens over Canadian Arctic
 

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Our democratically elected government is now muzzling scientists from discussing their published work.

All of this is appalling on so many levels.