News stories have been reporting that the IPCC will make a statement about the relation between global warming and hurricanes:
During marathon meetings in Paris, the Intergovernmental Panel on Climate Change approved language that said an increase in hurricane and tropical cyclone strength since 1970 "more likely than not" can be attributed to man-made global warming, according to Leonard Fields of Barbados and Cedric Nelom of Surinam.
The blogosphere is already awash with discussion about this (see here and here), and I expect all the usual suspects to weigh in on this soon.
Some commenters have been arguing that this statement fundamentally disagrees with a recent statement by the World Meteorological Organization (WMO). The implication is that this disagreement shows that the IPCC process cannot be trusted -- and therefore, we should not believe the IPCC's conclusions.
Let's compare their statements. In the IPCC's language, "more likely than not" means something like a 51% chance -- a smidge more than a coin flip. The alternative phrasing by the WMO is that while there is evidence "both for and against" a connection, "no firm conclusion can be made at this point." (PDF here).
To my eye, these statements mean pretty much the same thing. But like the hockey stick debate, I suspect that doesn't really matter much. What matters is that this mole hill will be blown up to a mountain by advocates who want to use this difference to launch attacks on the IPCC.
Sadly, this delightfully noisy but substance-free argument will take away from the IPCC's most important result: the Earth just keeps getting warmer, and we're primarily to blame.
(Also see my previous post on why we should trust the IPCC here.)
On ‘climategate’
What to make of the new climate poll
Comments
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Benny Big Eye Posted 6:59 am
01 Feb 2007
Yep. And it looks like one of the usual suspects is launching a preemptive strike.
Benny Big Eye
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Steve Bloom Posted 11:32 am
01 Feb 2007
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Andrew Dessler Posted 12:17 pm
01 Feb 2007
You're correct. Footnote 7 of the TAR WGI SPM did not list anything like that. On the other hand, "more likely than not" has a reasonably simple interpretation --- more so than words such as "likely". I'll be quite interested to see what actually comes out in the report.
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Steve Bloom Posted 7:52 pm
01 Feb 2007
Virtually certain > 99% probability of occurrence,
Extremely likely > 95%,
Very likely > 90%,
Likely > 66%,
More likely than not > 50%,
Unlikely < 33%,
Very unlikely < 10%,
Extremely unlikely < 5%
Hmm, "less likely" seems to be missing in action. Maybe they don't use it anywhere.
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asipocz Posted 2:19 am
02 Feb 2007
Lastly, Larry Soward, the commissioner of the Texas Council on Environmental Quality (our air and water quality agency) and the govenor's former chief of staff, gave the closing address. Started out normal, great job everyone etc., and then suddenly it seemed like he dropped his notes and went on a tear about how there is no downside to the reduction of green house gases. He discussed the adverse effects of climate change and rising seas on Texas very eloquently. The conference gave him a spontaneous standing ovation. Afterwards I learned it was the first time he gave this address. This is the agency that will have to approve new coal fired power plants in Texas.
Andrew Sipocz
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David Roberts Posted 2:22 am
02 Feb 2007
www.grist.org
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asipocz Posted 3:53 am
02 Feb 2007
Andrew Sipocz
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amazingdrx Posted 5:35 am
02 Feb 2007
Texas is number one in wind power, I think? In growth and installed capacity.
http://amazngdrx.blogharbor.com/blog
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merwin Posted 11:11 pm
07 Feb 2007
Could i ask you to put me on the right track here, since i'm discussing global warming and hurricanes in another forum.
The trouble i'm having is to define which statements that are acceptable in light of the WMO and/or the IPCC consensus. I'll use Katrina here as an example - but this really isn't about it. The discussion boils down to these two statements:
Katrina was caused by global warming
Katrina was not caused by global warming
From my personal reading both of these two statements are wrong. I know that its not possible to pin down the attribution in intensity to a single event, and i'm also well aware that the AMO probably has a much larger impact on north atlantic cyclones, and that land-use changes and development is the real culprit in the damages from hurricanes (both for Katrina and in general), since i do read prometheus once in a while...
Hopefully you can help me in assessing whether i'm correct or entirely off track in this. I don't mind being wrong - i'd rather correct any mistakes that i've made.
Thank you,
Kim.
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Andrew Dessler Posted 12:58 am
08 Feb 2007
It is impossible to attribute (at least with our current knowledge) any single event to global warming. Ditto for saying that global warming had no effect on any single event.
So, as you surmised, both statements are wrong: we cannot say what effect global warming had on Katrina.
What can you say? From the IPCC: Based on a range of models, it is likely that future tropical cyclones (typhoons and hurricanes) will become more intense, with larger peak wind speeds and more heavy precipitation associated with ongoing increases of tropical SSTs.
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