Business-as-usual estimates from MIT


in Politics, Science, The environment

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Researchers at MIT have updated their climatic models and reached conclusions generally in line with the Hadley Centre in the UK, in terms of the amount of warming that would occur by 2100 under a business-as-usual case, in which no significant emissions reductions are achieved:

[T]here is now a nine percent chance (about one in 11 odds) that the global average surface temperature would increase by more than 7°C (12.6°F) by the end of this century, compared with only a less than one percent chance (one in 100 odds) that warming would be limited to below 3°C (5.4°F).

It is difficult to express how enormous a change 7°C would be. Conservative estimates of the point at which anthropogenic climate change should be considered ‘dangerous’ tend to cluster around the 2°C target adopted by the European Union, and others. As the MIT model suggests, a world that does not mitigate emissions may face a 99% probability of experiencing average warming a full degree above that target.

When politicians talking about climate change say that they ‘accept the science,’ people should be asking them if these kinds of projections are part of the science they accept. If so, they ought to be asked why they are treating climate change with such an utter lack of seriousness, concentrating far more on matters of fleeting political concern. In retrospect, it seems that people three or four generations from now will judge our current leaders largely on the basis of their failure to respond effectively to this threat.

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{ 10 comments… read them below or add one }

Dave February 24, 2009 at 9:30 am

I certainly agree that future generations will judge us on our actions in the coming years – not to mention our actions in the past. Unfortunately, it seems that Canadian politics is moving in the opposite direction. We know full well that Stephen Harper cares little about the issue, except insofar as he can be forced into it by public opinion. And Ignatieff is little better, given his recent comments to the effect that we can use the oil sands to win concessions from the U.S.

Milan February 24, 2009 at 9:51 am


Leadership in Canada is not forthcoming. It is also a shame that carbon taxes (a perfectly good policy option) will always be associated with Dion’s failed leadership.

Anon February 24, 2009 at 2:03 pm

A lot of the uncertainty in climate projections comes from uncertainty about what emissions will be, rather than uncertainty about how the climate system will respond to any particular level of emissions. That is demonstrated by the Special Report on Emissions Scenarios (SRES) developed by the IPCC.

You can get hugely different results for the climate in 2100 by making different assumptions about how much coal, oil, and gas people will burn in the interim.

It is also challenging to define a ‘business-as-usual’ pathway. If we are going to see a temperature increase of over 3°C by 2100, it seems almost certain that whatever business exists in 2090 will not be ‘as usual’ by today’s standards.

. February 24, 2009 at 4:55 pm

Policy vs. No-Policy: Updated Estimates
Visualizing the risks and probabilities of success

mek February 25, 2009 at 6:43 am

Speak for yourself, Milan – in BC’s case, at least, carbon taxes are tolerated. While Canada’s chosen path (for now) is obviously environmentally destructive, Harper government policy is not nationally compelling.

Milan February 25, 2009 at 8:56 am

I hope you’re right.

The biggest problem with cap-and-trade schemes seems to be that they give governments too many opportunities to do special favours. The beauty of a carbon tax is that it should produce abatement at whatever sector and whichever facilities where doing so is cheapest. It is also comprehensible and comparably easy to administer.

Tristan February 25, 2009 at 9:23 am

I still believe Carbon taxes are politically possible in Canada. Dion with carbon taxes was a perfect storm – complex policy (not actually, but by election standards), inarticulate leader. And, it was something like a perfect storm in the liberal party which produced him as leader in the first place.

Milan February 25, 2009 at 10:11 am

In the end, though, carbon taxes are not the only sensible policy available. Cap-and-trade with 100% auctioning has most of the advantages, and the added perk that you can set a hard limit on total emissions.

Milan February 25, 2009 at 10:15 am

Also, the whole point of either system is to create certainty for businesses and individuals about paying a price for carbon in the future. The clearer the future values of that price, the more rational decisions can be made. As such, it probably would not be wise to move from a working cap-and-trade system to a carbon tax, or vice versa.

. February 25, 2009 at 4:29 pm

Getting real
M.I.T. joins climate realists, doubles its projection of global warming by 2100 to 5.1°C

The Massachusetts Institute of Technology Joint Program on the Science and Policy of Climate Change has joined the climate realists. The realists are the growing group of scientists who understand that the business as usual emissions path leads to unmitigated catastrophe (see, for instance, here and below).

“The take home message from the new greenhouse gamble wheels is that if we do little or nothing about lowering greenhouse gas emissions that the dangers are much greater than we thought three or four years ago,” said Ronald G. Prinn, professor of atmospheric chemistry at MIT. “It is making the impetus for serious policy much more urgent than we previously thought.”

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