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Global warming is "an emergency unlike anything humankind has ever faced before," Prof. Thomas Homer-Dixon argued Saturday in his Globe essay The sequel to Kyoto
"A few years ago, scientists regarded global warming as a matter of serious concern," he wrote.
"Now many appear to think that it's a matter of grave urgency — that we may be running out of time . . .
"Climate scientists are now beginning to discuss a topic that only two years ago many fervently hoped they'd never have to discuss — geoengineering, or the intentional human modification of the planet's climate to arrest or slow global warming.
Prof. Thomas Homer-Dixon
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"Geoengineering would involve, for example, putting sulphates aerosols into the atmosphere or putting mirrors into space to try to block a fraction of incoming solar radiation.
"Today the topic is at the margins of the public-policy dialogue about climate change.
"But I expect it will be at the centre of public discussion within five years.
"In 10 years, we will see demands from some segments of the public and many opinion leaders that we carry out geoengineering.
"And we'll probably start doing it within 20 years, likely when it becomes apparent that the Greenland ice sheet is starting to collapse."
Whether you agree or not, it's a provocative argument and we are pleased that Prof. Homer-Dixon was online earlier today to take your questions on this essay and on global warming.
Your questions and Prof. Homer-Dixon's answers appear at the bottom of this page.
Prof. Thomas Homer-Dixon holds the George Ignatieff Chair of Peace and Conflict Studies at the Trudeau Centre for Peace and Conflict Studies at University College, University of Toronto.
He was born in Victoria and received his B.A. in political science from Carleton University in 1980 and his Ph.D. from MIT in international relations and defense and arms control policy in 1989.
He then moved to the University of Toronto to lead several research projects studying the links between environmental stress and violence in developing countries.
Recently, his research has focused on threats to global security in the 21st century and on how societies adapt to complex economic, ecological, and technological change.
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Jim Sheppard, Executive Editor, globeandmail.com: Good morning, Prof. Homer-Dixon, and thanks for joining us today to take questions from the readers of globeandmail.com on your Globe essay last Saturday on global warming.
You presented a detailed argument that geo-engineering may eventually be necessary to reverse or slow down the current process of climate change.
Do you personally think the world will get to that stage within the next two decades? Or do you expect that enough action will be taken before then to make those kinds of dramatic moves unnecessary?
Prof. Thomas Homer-Dixon: First, let me be clear that I think geo-engineering is an appalling prospect. Some people misread my article as suggesting that I advocate this policy.
I was careful to write the piece simply to say that: (1) senior scientists are starting to talk about geo-engineering seriously because they think we may have to do it and (2) in my opinion, given the current trajectories of both emissions and warming, we will probably have to engage in some form of geo-engineering within the next few decades.
I don't like this conclusion at all, but the accumulating evidence drives me to it.
Globally, humankind has made virtually no progress on mitigation (cutting carbon emissions).
In fact, as I mentioned in the Saturday article, data recently released show that 2006 global carbon emissions were (at 8.4 billion tons) almost half a billion tons above the worst-case IPCC emissions estimate for the year.
