We hear a lot about climate "tipping points" in the news. You may very well be wondering what a tipping point is and whether it's something to be concerned about.
To understand a tipping point, imagine that you're sitting in a canoe and you start to lean your body over one side. The canoe will slowly rotate (I think the nautical term is "list") as you lean ever further -- until, that is, you lean just far enough, and suddenly the canoe flips over, sending you into the water. You've just encountered a tipping point.
The worry is that the climate will slowly warm as CO2 is added -- until we cross a tipping point, at which point the climate abruptly shifts into a new and possibly very different state. If this happens, it would likely be a disaster of Biblical proportions, unleashing unimaginable suffering and hardship.
The two most often talked about are a shutdown of the thermohaline circulation, which could cause a rapid cooling of Western Europe, or a disintegration of the West Antarctic Ice Sheet, which would raise sea levels by about 20 feet.
We have evidence that both these things have occurred in the past, so we must consider the possibility they could happen again. However, most scientists believe the chance that these or other tipping points will be reached this century is remote. Climate models do not predict their occurrence in the next century, nor do we have any direct evidence of an impending tipping point.
As a society, we are relatively good at dealing with obvious, near-term risks. One of the many challenges for policymakers is to construct a climate policy that accounts for low-risk but high-consequence events like climate tipping points.
What about people like Jim Hansen who say that we're 10 years from a tipping point? They are using the term in a different way. What they're saying is that if we take no action to reduce greenhouse-gas emissions within 10 years, we'll pass some threshold where severe and possibly irreversible climate impacts will become unavoidable. This might be right (there is much uncertainty in the science behind it), but it is also quite different from the canoe-model tipping point.
Realclimate has a post on this topic that is also worth reading.
‘Copenhagen Diagnosis’ offers a grim update to the IPCC’s climate science
Cast your vote for the best climate journalism
The science behind a climate headline
Comments
View as Flat
Zarkov Posted 7:37 am
06 Nov 2006
as if, Katrina is just classical :)
>> people like Jim Hansen who say that we're 10 years from a tipping point?
or maybe we have already past it, years ago ! LOL
You think there is a way out of this don't you ?
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johnmcc793 Posted 12:27 am
10 Nov 2006
I contend we would not recognize a tipping point, in our lifetime, if it hit us in the face.
Is the now-accelerated melting of the Andean glaciers a 'tipping point' for the world of AGW believers? Seems not. But, it is a large and frightening moment in time for down slope farmers, villagers and municipalities reliant upon glacial melt water for irrigation and drinking water.
Lets assume Dr. Hansen is correct in saying that we're 10 years from a tipping point...I agree with him we are ten years or less from more consequences of a warming world. Starting the clock today, I can assure you the politics in the US, Australia, China and India are not in place nor in the riaght frame of mind to do much of anything to [reduce greenhouse-gas emissions within 10 years]. Thus, [we'll pass some threshold where severe and possibly irreversible climate impacts will become unavoidable]. I accepted that as well --- about ten years ago.
The Nov. 10, Washington Post opinion piece of Robert Samuelson " Greenhouse Guessing" at:
http://tinyurl.com/uoa79
is a graphic depic...
It is an 8 meg report but it will convince you, perhaps, that having reached a "tipping point" might depend upon where you stand and when it changes your life.
John L. McCormick
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johnmcc793 Posted 12:50 am
10 Nov 2006
take it from here :
depiction of the paralysis of the AGW response. Whether you agree with his views or not, they are the backdrop for Dr. Hansen's warning and one might conclude they represent the political tipping point of AGW debate.
He says people say they are worried but don't act that way. Climate-forcing emissions continue to rise despite the Kyoto Protocol. Why?
In his words:
"With Today's technologies, we don't know how to cut greenhouse gases in politically and economically acceptable ways" my comment: Please refrain from saying renewables and conservation if you believe Dr. Hansen's warning.
"In rich democracies, policies that might curb greenhouse gases require politicians and the public to act in exceptionally "enlightened" (read: "unrealistic") ways." My comment: That holds true for the US 110th Congress under control of the Democratic party.
"Even if rich countries cut emissions, it won't make much difference unless poor countries do likewise - and so far, they've refused because that might jeopardize their economic growth and poverty-reduction efforts." My comment: Peruvians measure the lost glacial melt runoff in economic terms but are powerless to reverse the inevitability of greater reduced stream flow. Likewise for farmers and villagers reliant upon diminishing flows from diminishing Himalayan glaciers. Globally or locally, we don't miss the water til the well runs dry.
In conclusion, Mr. Samuelson's view is hard to argue. And, he has just described the political and economic dynamics that will forever follow closely behind the global AGW debate..... perhaps not in every instance but he has described the dark cloud hanging over the UNFCCC COP 12. Politicians are hard-wired in ways that Samuelson described.
So, tipping points come and go, as former residents of New Orleans know first hand. Inuit and Maldevians will have their own tipping points to confront.
I believe firmly that the world community had a moment of truth back in 1958 and 1959 when Dr. Keeling documented CO2 atmospheric concentrations were increasing. We did not act then for reasons of ignorance of the consequences. Today and tomorrow we will not act for reasons of Mr. Samuelson's rendition.
Two essential components of human survival are water and food...in that order. Read the recently published UN Development Program's "Human Development Report, 2006"
At:
http://tinyurl.com/y72yjz
It is an 8 meg report but it will convince you, perhaps, that having reached a "tipping point" might depend upon where you stand and when it changes your life.
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EliRabett Posted 4:51 am
10 Nov 2006
I on the other hand see the climate war tipping points as cultural.
As an aside I see Coby and you joining the blorg as a step backwards.
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