Of course, we'll never be absolutely certain about the causes and future trends of climate change. That's not the way science works. But according to the Intergovernmental Panel on Climate Change, we're getting pretty darn close to that magical 19-times-out-of-20 territory that passes for conclusive evidence in scientific language.
The Toronto Star has got ahold of what is most like a next-to-final draft of the IPCC next report, due Feb. 2, and the language could scarcely be more worrisome. Here are the excerpts,as reported by Peter Gorrie:
"It is very likely that (man-made) greenhouse gas increases caused most of the globally average temperature increases since the mid-20th century."
"Discernible human influences now extend to other aspects of climate, including continental average temperatures, atmospheric circulation patterns and some types of extremes."
It is "very likely that hot extremes, heat waves and heavy precipitation events will continue to become more frequent."
"[The multitude of authors] support the conclusion that it is extremely unlikely that global climate change of the past 50 years" was caused by solar flares or other natural events..
There's also the almost prosaic, at this point:
"Warming of the climate system is unequivocal."
And the somewhat more equivocal:
"Values higher than 4.5 C cannot be excluded" because of "feedbacks," such as the increased ability of the atmosphere to absorb water vapour - an extremely potent greenhouse gas - as it heats up, and the greater warmth absorbed as Arctic ice melts.
The New York Times' Andrew Revkin weighed in a day later. His version of the story contains no quotes, because
"The language is far from final," said Kevin E. Trenberth, a senior scientist at the National Center for Atmospheric Research in Boulder, Colo., who is a lead author of one section. "You can't say what the I.P.C.C. says until it actually says it."
But really, Feb. 2 is only a few days away, so how much is it going to change? But Revkin does make mention of some important numbers, such as:
...it is more than 90 percent likely that global warming since 1950 has been driven mainly by the buildup of carbon dioxide and other heat-trapping greenhouse gases, and that more warming and rising sea levels are on the way.
...
In its last report, published in 2001, the panel concluded that there was a 66 to 90 percent chance that human activities were driving the most recent warming.
...
Drafts of the report project a most likely warming of 4 to 8 degrees if the concentration of carbon dioxide in the atmosphere rises to twice the 280 parts per million that it averaged for many centuries before the Industrial Revolution.
It will be interesting if Trenberth's hint of substantial edits to come prove prescient. But considering that none of what we've seen so far strays far from the overwhelming consensus, I would think that it would hard to justify significant changes to either the levels of certainty expressed or the range of values provided.
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In the context of statistical testing, a .95 confidence level has a clear meaning. In the present context, I fear, such claims are rhetorical fluff, being based on little more than "gut feelings." Of course gut feelings have a place in scientific practice, since scientists are creatures with guts. But dressing up feelings in statistical garb doesn't make them objective measures of likelihood.
Bob Koepp: You're right. The weakening of their statement to only 90% rather than the scientifically justified virtually 100% likelyhood is about the US's "gut feelings" that anything except uncontrolled burning of fossil fuels is behind the globalwide increase in temperatures.
The science is in at this point: We are driving the climate change. We aren't arguing about that now: We are arguing about how bad is it going to get and how fast.
I am cynical enough that I don't believe the US will take effective action to control CO2 emissions until it is much too late. Once the climate feedbacks kick in, we aren't at the steering wheel anymore. At that point, we are in for a wild ride as the climate system switches from 'ice planet' to 'hothouse planet' mode.
I'm just lucky to be old enough that I probably won't live to see it get really bad.
Probably.
I guess I would have to agree with Benjamin as well...that is, regarding the cynicism of actually doing something about CO2 emissions in the US.
In a weird way, it's unfortunate that the CO2/global warming connection (or misinformation) gets so much attention in the press. There are myriad of reasons to cut emissions in addition to the greenhouse pollution reason. All under the umbrella of reducing energy consumption in general. If, as Benjamin points out, the feedbacks really get going...we oughta be focused on adaptation to climate rather than management of it.
Wouldn't that be something. Once all the contrarians are convinced that humans caused climate change and they are ready to do something...the scientific community turns around and says 'it's too late, nothing we do can affect the climatic system now'. Man, will they be ticked off.
Criticizing the rhetorical use of scientific terminology isn't quite the same as denying AGW. My comment reflects more my concern about damage being done to the integrity of scientific processes than the damage being done to our environment. But I imagine people will still find reasons to take offense.
Do you see the latest story about Climate Change?
Due to constant sea level rising, Ashar Chorâs natives are already moving to other parts of the country. This is resulting to an increase in the number of climate refugees in Bangladesh. There have been 62 weather-related disasters in Bangladesh since 2000 and that the number is set to rise as global warming rises.
The Bangladeshi delegation argues strongly that industrialized countries should agree to cut their emissions by 25%-40% in the next 15 years to reduce the effect of global warming, and all countries should agree to a binding obligation to reduce carbon emissions. Although it is a good initiative that has been taken; hopefully is going to be established within the 15 years predictable time line. Though we do not know when and how Mother Nature is going to change its face to brutality again and constant sea level rise never stops. The effects of climate changes, The Ashar Chor Island may vanish after five to ten years later.
http://www.globalpost.com/dispatch/global-green/091223/sinking-island-c…