Wednesday, December 02, 2015

Trivial pursuits

So for some reason I got invited to participate in the latest Bray and von Storch survey of climate scientists, having not (IIRC) been asked previously. I barely got started on the meat of it before giving up. Screeds of hopelessly vague multi-choice questions with no context, like: how well do you think climate models can deal with clouds (answer from "very adequate" to "very inadequate"). Can or do deal with? Adequate for what? I'm not impressed.

More interestingly, I swapped a couple of emails with the author of this article over the past couple of weeks while he was writing it. Seems that I didn't say anything quotable enough to get quoted in it, but it looks pretty good to me.

Edit: Oops, first time round I was focussing on the quotable quotes to see if I disagreed with them. On a more careful re-read the author seems to think the last glacial maximum was only 1C colder than the present. No, it was 4C colder (than pre-industrial, ie 5C colder than now).

12 comments:

EliRabett said...

Oher than disagreeing pretty violently with the article, what is there to say. The most important number IEHO is total emissions. Climate sensitivity is the luckwarmers cuddle blanket for reasons the idiot tracker laid out.

http://theidiottracker.blogspot.fr/2010/09/between-science-and-hard-place-part-two.html
http://theidiottracker.blogspot.com/2010/09/between-science-and-hard-place.html

Doug McNeall said...

The author clearly hasn't been keeping up to date with their required portion of XKCD. https://xkcd.com/1379/

Paul Skeoch said...

From the perspective of the thousands of years preceding the LGM it may have only been a 1C drop... but maybe that's missing the point.

James Annan said...

The prior interglacial we had hippos living round these parts...

EliRabett said...

Hippies?

Paul Skeoch said...

I've always found it odd that the LGM is talked about in terms of a cooling from present day, rather than present day as a warming from the LGM :)

James Annan said...

Paleo people usually have time running backwards :-)

Unknown said...

Whoops! That's my bad on the temp difference. Fortunately, this is the web so I've fixed it. Do let me know if you find any other factual errors and thanks again for your help.

MikeR said...

"The most important number IEHO is total emissions." Rabbett, I can't follow this. Why isn't it essential to know how much temperature rise there will be? That would seem to be the money number, not the two numbers that go into it (emissions, sensitivity)? That is what determines damage, more or less, and therefore how far we would need to go to offset the damage.
Are we really bound by idiottracker's opinions on the "scientific consensus" on sensitivity, ignoring more recent results, and also by his opinions, stricter than the consensus, on how much warming is disastrous? The net effect seems to me to be an attempt to convince the rest of us to focus only on the more alarming possibilities.

crandles said...

> I can't follow this. Why isn't it essential to know how much temperature rise there will be?

Part of the trillion tons stuff perhaps:
"We find that the peak warming caused by a given cumulative carbon dioxide emission is better constrained than the warming response to a stabilization scenario."
http://www.nature.com/nature/journal/v458/n7242/abs/nature08019.html

Obviously there is uncertainty and we cannot know exactly how much warming there will be. Minimising that uncertainty would be useful.

It is being suggested there is less uncertainty looking at total cumulative emissions than using the atmospheric GG levels and an uncertain sensitivity number.

However, I am not sure that I follow correctly. Knowing the total cumulative emissions so far does not tell you with certainty the eventual cumulative emissions or the final atmospheric level. Is it getting to less total uncertainty by assuming knowledge of future emissions levels? Or maybe atmospheric level and an uncertain sensitivity number is a bad way to dice and splice the uncertainties?

Is there really less uncertainty using total emissions? Surely your real best estimate of the actual uncertainty in future temperature rise is that amount of uncertainty however you dice and splice it?

Perhaps Eli is thinking rather differently.

A simpler possibility might be:
Asking for the actual future temperature rise is just asking for the unobtainable. There is the expected future temperature rise and there is the uncertainty in that number but that is more than one number whereas total emissions is one number that implies both of those.

BBD said...

From the SA article:

Take for example the Eocene, some 30 million years ago, the warmest period in recent Earth history where atmospheric concentrations of CO2 rose above 700 ppm and palm trees and crocodile-like animals thrived in near Arctic latitudes.

Nit-picky, I know, but the Eocene *ended* nearly four million years before the date given.

MikeR said...

"Asking for the actual future temperature rise is just asking for the unobtainable." I hear, but I don't know what the conclusion should be. Tell me an estimate of the damages, tell me the cost of avoiding various levels of CO2, and I can try to make an actuarial estimate of how much avoidance is appropriate. Refuse to tell me the damages and I will only be able to act if I believe that the cost is zero.
I know that there are those who believe that - but many people don't. They feel that minor mitigation is going to accomplish little, and major mitigation is going to kill lots of people: people who live out their short lives in poverty in places like India and Africa when easier access to energy would have raised them up and saved them. That's a big cost, a tremendous cost. Don't expect them to support major mitigation if you can't convince them that the damage exceeds that cost.