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Research says 'enact policies now' to limit risk of climate catastrophe

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October 6, 2009

Ronald Prinn, director of MIT's Center for Global Change Science, and his group have revis...

Ronald Prinn, director of MIT's Center for Global Change Science, and his group have revised their model showing how much hotter the Earth's climate will get in this century. (Photo: Donna Coveney)

Researchers at MIT have continued a study of climate risk and released a new report to show that even moderate carbon-reduction policies can substantially lower the risk of future climate change. It also shows that action is needed quickly if global emissions reductions are to provide a good chance of avoiding a temperature increase of more than 2°C above the pre-industrial level — a widely discussed target. But the researchers determined that failing to take prompt action could result in extreme changes that could become much more difficult, if not impossible, to control.

“Our results show we still have around a 50-50 chance of stabilizing the climate at a level of no more than a few tenths above the 2°C target," says Ron Prinn, co-director of MIT's Joint Program on the Science and Policy of Global Change and a co-author of the new study. "However, that will require global emissions, which are now growing, to start downward almost immediately. That result could be achieved if the aggressive emissions targets in current U.S. climate bills were met, and matched by other wealthy countries, and if China and other large developing countries followed suit with only a decade or two delay. That 2°C increase is a level that is considered likely to prevent some of the most catastrophic potential effects of climate change, such as major increases in global sea level and disruption of agriculture and natural ecosystems.”

"The nature of the problem is one of minimizing risk," explains Mort Webster, assistant professor of engineering systems, who was the lead author of the new report. He says the public discussion over climate change policies gets polarized as a debate between extreme views such as: “the world is ending tomorrow, versus it's all a myth," he says. "Neither of those is scientifically correct or socially useful."

"It's a tradeoff between risks," he says. "There's the risk of extreme climate change but there's also a risk of higher costs. As scientists, we don't choose what's the right level of risk for society, but we show what the risks are either way."

That's why the research team looked at the probabilities of various outcomes, rather than focusing on the average outcome in a given climate model, he said. It was “a more useful way to think about it,” he added.

The new study, published online by the Joint Program, builds on one Gizmag covered earlier this year that looked at the probabilities of various climate outcomes in the event that no emissions-control policies at all were implemented. It found alarming probabilities of extreme temperature increases that could devastate human societies. This study examined the difference that would be made to those probabilities under four different versions of possible emissions-reduction policies.

Not reinventing the wheel

Both studies used the MIT Integrated Global Systems Model, a detailed computer simulation of global economic activity and climate processes that has been developed and refined by the Joint Program on the Science and Policy of Global Change since the early 1990s.

This new research involved hundreds of runs of the model using slight variations in input parameters, so that each run had about an equal chance of being correct based on what scientists know and understand currently. The MIT model is the only one that interactively includes detailed treatment of possible changes in human activities — such as the degree of economic growth, with its associated energy use, in different countries.

Quantifying the odds

"One of the common mistakes in the [scientific] literature," says Webster, "is to take several different climate models, each of which gives a 'best guess' of temperature outcomes, and take that as the uncertainty range. But that's not right. The range of uncertainty is actually much wider."

This study produced a direct estimate of probabilities by running 400 different probability-weighted simulations for each policy case, looking at the actual range of uncertainty for each of the many factors that go into the model, and how they interact. By doing so, the researchers say it produced more realistic estimates of the likelihood of various outcomes than other procedures — and the resulting odds are often significantly worse.

They say an earlier study, by Tom Wigley of the National Center for Atmospheric Research, estimated that the Level 1 emissions control policy — the least-restrictive of the standards studied - would reduce by 50 percent the odds of a temperature increase of more than 2°C, but the more detailed analysis in the new study finds only a 20 percent chance of avoiding such an increase.

The good news is that the team found that even relatively modest emissions-control policies can have a big impact on the odds of the most damaging climate outcomes. For example, under the strongest of the four policy options, the average projected outcome was a 1.7°C reduction of the expected temperature increase in 2100, but for the most extreme projected increase (with 5 percent probability of occurring) there was a 3.2°C reduction. And that's especially significant, the authors say, because the most damaging effects of climate change increase drastically with higher temperature, in a very non-linear way.

"These results illustrate that even relatively loose constraints on emissions reduce greatly the chance of an extreme temperature increase, which is associated with the greatest damage," the report concludes.

Webster says: "this is a problem of risk management," and adds that, while the technical aspects of the models are complex, the results provide information that's not much different from decisions that people face every day. He used the analogy of people using their seat belts and having a car with airbags to reducing the risks of injuries while driving, but that it didn’t mean they couldn’t still be injured or killed. "No, but the risk goes down. That's the return on your decision. It's not something that's so unfamiliar to people. We may make sure to buy a car with airbags, but we don't refuse to leave the house. That's the nature of the kind of tradeoffs we have to make as a society."

4 Comments

This article exemplifies the sales problem global warming has faced. Nowhere in this article is there any observed data. We'd all like the honor of actually proving AGW exists, so it's a challenge for anybody including these guys.

"Running 400 different probability-weighted simulations" is NOT scientific proof of AGW. It is proof that they ran 400 simulations. How about running 500 simulations? Or 600? Will that create even more proof?

Several years ago the same MIT model predicted that ocean levels would be up a foot by this very time. And to their credit MIT has been straightforward about adjusting the model.

The polar icecaps are exactly where they should be, and are not shrinking. If they were, it would be plain to see everywhere in the media, and not just the eco-blogs. If the warmists would just provide actual observed data, we would be convinced. But in lieu of that I understand their frustration.

Todd Dunning
6th October, 2009 @ 10:19 pm PDT

Why won't the just admit that the planet goes through warming and cooling cycles (probably caused by the sun) that run approximately 500 years. It is funny, but many of you probably remember that in the late 60s "science" was fearful of a new iceage. It doesn't appear that Greenland was always under ice. Will our behavior change the forest fires, volcanos and the ice caps on mars?

All of this said, I like electric vehicle technology and good stewardship. It would be nice to see data and hear honesty instead of fear mongering and deception by Al Gore ditto heads.

Wade A Patterson
7th October, 2009 @ 07:42 am PDT

I'm always suspicious when someone tells me that if they have found the perfect solution to all my problems... this new item cleans my house, makes my grass green, finds me a better job, picks the kids up from school, and makes my car run without gasoline.

Now we come to Global Warming... which amazingly enough happens to perfectly match everything ecology movements have wanted for 50 years... and I do mean everything. Wouldn't you think there'd be at least one area where prior ecological movements and the Global Warming theory didn't overlap? An instance where ecologists were wrong and something needed to be done that wasn't exactly in line with everything they've ever wanted?

If Global Warming were a serious threat to life and the planet, wouldn't every single ecologist be urgently advocating the largest actions that can be taken with current technology? For instance, it is physically possible that 100% of electrical generation be moved to nuclear technology, isn't it? If money were no object, plants could be built to cover the electrical needs of the world. They'd certainly end the lion's share of man-made carbon production, and by moving transportation to electrical also, possibly end virtually all of it. Since that's actually possible... we have the technology today... you would expect to see the majority of global warmingists pushing for it, wouldn't you?

Instead, we hear about "cap and trade" bills, carbon credits (which increase costs, and government revenues, but do little to actually reduce CO2 output), wind and solar energy... technologies that are still unable to pay for themselves (come on, you can't count government subsidies in that formula) and are certainly unable to replace even a noticeable percentage of current energy production, let alone 100%.

If it really really requires a reduction in output of CO2 of, say, 10% or else THE WORLD ENDS!!!!! and China and India insist they need to push out more... aren't they threatening the world with extinction? Wouldn't this be the time to say "reduce, or we'll reduce your output for you"? Or, perhaps, is it not really that serious?

Global Warming just seems too much like the terminal disease my neighbor Vinnie contracted... poor guy says he has to sleep with a new woman every night, or else die... thankfully, he seems to find an unending stream of generous women to help him cope. Funny thing... they all drive Prius's.

Eddie Sarphie
11th October, 2009 @ 09:11 am PDT

The Global Warming Hoax has permenantly damaged the reputation of science .

Every single self-serving scientist supporting Global Warming should be listed and fired

and never again allowed to be paid with any taxpayer funds..

bgstrong
31st May, 2011 @ 07:35 am PDT
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