What will I be looking for in the SPM4? There’s not much fun in trying to predict their temperature estimate when they’ve already leaked that it’s 2-4.5 deg C by 2100. So here are some things that I’m going to be looking for.
1. First – and I realize that it’s far down the list for the world at large – but, if you’ll forgive me a little self-indulgence, I’ll check to confirm that “warmest in 1300 years” or “hottest in 1300 years” made it into the SPM. It would be fun if a spaghetti graph made it up the food chain, but that would be a pleasant surprise
2. Second, I’ll see if a “battalion of intergalactic smoking missiles” has arrived in Paris, as Andrew Weaver has told us. Since this document is supposed to a Summary of the WG1 Report, which itself was a literature review, it’s hard to see how even resourceful IPCC couriers could have smuggled an “intergalactic smoking missile” through security into Paris for presentation as new evidence tomorrow – it won’t be like one of the old Russian May Day parades. If IPCC council changes a probability rating of something from likely to very likely, that is not something that I would regard as an intergalactic smoking missile, although maybe this is a big deal in Team-world and to the BBC. Do I expect any new evidence in the SPM? No.
3. Third, I’ll cross-check the SPM4 to the TAR SPM (SPM3). My guess is that some of the statements in the two documents are going to be surprisingly similar. For example, SPM3 said: “…There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities.” I suspect that SPM4 will also say “…There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities.” However, it seems to me that most of the evidence available today – whatever its merit – was equally in play in 2001. So it will be interesting to see whether they specify what the “new and stronger” !$r evidence is.
4. Antarctica seems to be a bit of a battleground issue between IPCC factions. TAR said that Antarctic was projected to gain mass in the 21st century. The WG1 text said that precipitation over Antarctica would increase and that the resulting accumulation on the continent would have a negative impact on sea levels. Obviously some factions want to project melting in Antarctica and a positive contribution to sea levels. So let’s watch what happens. Will they mention “polar amplification”? Given recent cooling over Antarctic, my guess is that the term will not be used.
5. I think that we’ll hear a lot more in SPM4 than SPM3 about the Four Horsemen of the New Apocalypse: Drought, Hurricanes, Sea Level Rise and you-pick-it (Sea Ice Decline, Heat Waves, even old-fashioned Pestilence, although it is more a WG2 interest). The Horsemen of the Apocalypse only had bit roles in TAR WG1. Here I’ll be looking for language. Drought is particularly interesting as the WG1 paleoclimate chapter says that there is proxy evidence for much more extensive historic droughts than modern droughts and the model projections chapter reports moister monsoons under global warming. However, one suspects that they will try to saddle up Drought on a pale horse.
6. It sounds like they’re going to take a swipe at solar and promote the low variability view of Wang et al 2005. I get the impression that Wang et al 2005 is very speculative and not the sort of thing that should be incorporated into a mainstream poilcy position at this point. However, this will be amusing if they do, since the low variability Wang solar theory is inconsistent with solar irradiance in all the millennium paleoclimate simulations.
7. In one press story, they said the following:
11 of the past 12 years rank among the warmest since humans began taking accurate temperature measurements in the 1850s, a record of extremes so pronounced it is unlikely to be due to chance.
The WG1 report does not include the last phrase. Was this inserted in the press story or the leaked SPM? It would be delicious if it were in the SPM, since this introduces a statistical opinion on long-term persistence that seems outside the mandate of the SPM authors. Will they add this phraseology back into the AR4 to make it “consistent” with the SPM? Or just ignore the inconsistency?
8. I guess that we already know that their temperature projection to 2100 is 2-4.5 deg C (as opposed to 1.4-5.8 deg C in 2001). A story says that the report says “Large uncertainties remain about how clouds might respond to global climate change”. I’ll check to see. Im sure that they’ll say that “models are improving”. Just to demonstrate the remarkable progress in understanding over only one generation, the Charney Report in 1979, an interesting commissioned report by a NAS panel on 2xCO2 by eminent scientists, estimated the effect of 2x CO2 to be 1.5-4.5 deg C, said that the biggest problem with models and the biggest contribution to uncertainty was clouds, but that models are improving. Ten years earlier, Joni Mitchell said it better:
Rows and floes of angel hair
And ice cream castles in the air
And feather canyons ev’rywhere
I’ve looked at clouds that way
But now they only block the sun
They rain and snow on ev’ryone
So many things I would have done
But clouds got in my way
I’ve looked at clouds from both sides now
From up and down, and still somehow
It’s cloud illusions I recall
I really don’t know clouds at all
Here are some URLs to news stories about the preview that readers have sent in or that I’ve noticed.
CNN http://www.cnn.com/2007/TECH/science/01/23/climate.report.ap/index.html This isn’t a smoking gun; climate is a batallion of intergalactic smoking missiles.”
MSNBC http://www.msnbc.msn.com/id/16760730/ S
http://www.msnbc.msn.com/id/16884620/ clouds a puzzle