Margaret Munro, with files from Mike De Souza, The Ottawa CitizenPublished: Thursday, May 15, 2008
Shrinking glaciers, melting permafrost, earlier spring river runoff, and warmer water bodies point to pervasive physical changes, they say.
And earlier spring blossoms, bird migrations and altered distribution -- salmon showing up in the Arctic, the mountain pine beetle expanding into vast tracks of Western Canada's forests -- point to the many biological impacts.
"Significant changes in physical and biological systems are occurring on all continents and in most oceans," the international team reported yesterday in the journal Nature.
The study's release coincides with an announcement yesterday by the U.S. government declaring polar bears a threatened species due to shrinking Arctic sea ice caused by global warming. Canada has not made a similar announcement.
Meanwhile, the study builds on the work of the United Nations' Intergovernmental Panel on Climate Change, which last year concluded that human-induced climate warming is "likely" -- within 66 to 90 per cent probability -- having a "discernible" effect on physical and biological systems.
The new study mined even more data and concludes human-influenced climate change is the main driver of what is being observed, outstripping more modest effects of deforestation and other land-use changes.
"Anthropogenic climate change is having a significant impact on physical and biological systems globally," says the team, led by Cynthia Rosenzweig of at Columbia University in New York.
The team analysed data from hundreds of studies in peer-reviewed journals since 1970 and is the first to "formally" link observed global changes in physical and biological systems to human-induced climate change and greenhouse, says Francis Zwiers, director of climate research at Environment Canada.
"Making the link using a rigorous scientific method is a pretty big advance," says Mr. Zwiers, co-author of a commentary on the study, also in Nature.
The study is not without its limitations, says Mr. Zwiers. It would be better to have evidence stretching back 50 to 100 years, but he says the study "largely overcomes the sampling limitations because of the sheer number of changes" included in the assessment.
Meanwhile, the federal government reacted to the U.S. announcement on polar bears, saying the concerns raised are clearly linked to global warming and the urgency of addressing pollution from industry.
"Let's be clear that there's no doubt that global warming is a major factor and a major concern in this," Environment Minister John Baird said. "It's not just global warming, but it's human-induced global warming which is what we need to take action on."
Conservation groups said Mr. Baird should follow through next month by clearly establishing a conservation plan if his government gives a green light to major oil and gas companies for new exploration in the Beaufort Sea, where melting ice and declining populations are considered to be a particular concern to polar bear populations.
The Canadian Arctic is home to 13 of 19 polar bear populations in the world, while the U.S. is home to two. Mr. Baird has indicated he plans to accept recommendations of an independent Canadian panel that suggested polar bears should be listed as a species of special concern -- a category below threatened or endangered.
Source : http://www.canada.com/ottawacitizen/news/story.html?id=4d409262-a3d9-40b6-8c54-5cf08a15f948
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