Monday, June 19, 2006

Workshop talks

I'm off to the UK shortly, for a workshop on "Uncertainty, Probability, Models and Climate Change". It is such a highly top secret event that there is nothing about it on the web - in fact, there doesn't seem to be a programme yet at all - but that's ok cos it doesn't start until next week :-)

I understand that workshops such as this one represent the new NERC funding model - they won't actually pay anyone to do any research any more, but they will pay for us to talk to each other about what we would do if we had any money :-) I'm not complaining because I get a ticket home and I'm having a few extra days of holiday while I am there.

I'm giving two talks, which I've put here and here. I'm hoping that the first in particular will provoke a bit of discussion - the list of attendees includes some of those who have published extremely alarming "pdfs" in prominent journals, so it will be interesting to hear their defence.

5 comments:

Peter Hearnden said...

Caution, rant coming up...

Why can't these things be done by video conference? Why do scientists who know what is happening, have to go flying around the world to conferences that, if they find out, the sceptics will have a field day with? 'You don't think AGW is a problem else why are you swanning of to talking shops with you're mates?' they'll say 'Just wasting tax payer money, scrap the lot of them and stop them living of my tax' they'll add. Why do I both to try and tread lightly on the earth (and it's difficult and I'm not perfect either) when scientsts who COULD make a visible stand don't? Why did I protest to the NERC at recent cutbacks and then find they're funding climate scientists to go swaning around etc etc etc.

Perhaps AGW is all hype, spin put out by scientists who want to go to conferneces around the world and who see where the money is? Etc etc etc

Sorry.

Phil Hays said...

The climate sensitivity (defined as climate change for a doubling of CO2, for a short term, say roughly half a century) is roughly 3C, for a range of climates that extends from the LGM to today's climate, at minimum. However, climates outside that range may have rather different climate sensitivities.

The most compelling case for a large climate sensitivity comes from the Neoproterozoic. During this time, there is evidence that the entire surface was covered by ice, allowing the oceans to become oxygen free and setting up the conditions for depositing BIFs (banded iron formations).

Computer simulations suggest that when the polar ice cover gets to about 30 degrees from the equator, a very tiny decrease in CO2 causes runaway ice albedo and a frozen world, some 35C colder. This is a "tipping point" of climate.

http://www.nature.com/nature/journal/v405/n6785/fig_tab/405425a0_F2.html

For a tiny decrease of CO2 below the threshold, this freezing takes a few thousand years, as it requires growth of ice sheets. For CO2 at half of the threshold, it happens much faster.

Warmer climates are of more interest. If computer models could accurately reproduce past warmer climates, I would agree that there is little reason to suspect any serious non-linearity in climate in the warmer direction. Yet this does not seem to be the case. An ice free Arctic seems to have been present with CO2 levels not much different than today's level, and tropical temperatures seem to have been present with CO2 levels roughly 4 to 8 times current levels. Climate models do not reproduce either case. This leads me to suspect that there is a positive feedback in the Arctic that is not properly accounted for.

In terms of objections, I see two. The first is the artificial definition of climate sensitivity, which ignores slower feedbacks. If the missing feedback turns out to require a slow change, such as the deep oceans to warm, which will take at least hundreds of years, then it does not change the climate sensitivity as defined above. The second is the imperfect nature of understanding of past climates and climate boundary conditions.

Kit Stolz said...

The way you laid out the first talk was so clear even a non-mathematician such as I could follow it, mostly.

I hope you'll report back from the conference. As the top secret regulations allow, of course.

Anonymous said...

so you and your wife are still infighting with others about a 4.5K or a 6.8K or a 10K max sensitivity. Meanwhile McIntyre & McKitrick have just blown the hockey stick to pieces with the NAS report. So you have half a step forward and 10 steps back!

James Annan said...

Kit,

It wasn't really secret, just a bit ad-hoc in organisational terms :-) All the talks will probably be put on a web page some time. I will try to gather my thoughts although it was mostly rather technical for blogging.

Peter's rant is such a high quality it deserves a whole post in response :-)