Stern takes bleaker view on warming?

Says the FT, via DSB. Since I've already argued that Stern is over-bleak, Im surprised he has got more pessimistic. Whats up?

Apparently "We underestimated the risks . . . we underestimated the damage associated with the temperature increases . . . and we underestimated the probabilities of temperature increases.... Stern said data published since the report came out had led him to change his mind.

Aha! Interesting. What is this new data?

He highlighted the publication last year of the most comprehensive study yet undertaken of climate change science. Conducted by the Intergovernmental Panel on Climate Change, a body of the world's leading climate scientists convened by the United Nations, it predicted a temperature rise of 3°C within the next 100 years.

Well, no, it didn't; but you're not going tooo far wrong reading it to say that. However, all that was available from the TAR. The AR4 didn't really revise any TAR projections. So Sterns assertion that new data has caused him to revise his opinions would seem to be nonsense.

Catastrophic consequences for the planet were predicted unless greenhouse gas emissions were stabilised and then cut within the next decade.

And now we're off in la-la land. Who appointed this man to do a serious review? Though to be fair to Stern (must I be?) those may be the FTs words rather than his, its hard to be sure.

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I don't yet know enough about Stern's latest comments, but:

neo-classical economics =>
standard economic forecasts of growth =>
Stern Report

and I'm starting worried that neoclassical econ isn't a good approximation for the next century, i.e., a nice 1-3% CAGR for GDP.

I don't understand neo-classical econ well enough, but to be honest, the biophysical economics of Charlie Hall, or Bob Ayres/Benjamin Warr makes a lot more sense to me, and in the presence of Peak Oil+Gas, which neoclassical economics seems to ignore, the biophysical econ makes *very* different predictions about the economic trajectory over the next 100 years.

If the standard stuff is right, then people can argue about discount rates as much as they like - continued growth takes care of it.

If the biophysical folks are right, discount rate arguments aren't going to matter so much, and there won't be much of this "everybody will be a lot richer" belief. There will be a lot of "where will we get enough energy to keep GDP even flat? or keep the lights on?" (coal?)

They have some pretty good models that seem to show that the largest component of economic growth is energy-used * efficiency = work done, and that with oil+gas going down, efficiency must go up very fast just to stay even.

See page 46 of Ayres PPT , or see Ayres paper or Charlie Hall's balloon graph.
Also, Hall's Need to Reintegrate the Natural Sciences with Economics is good.

I'm sensitized to all this by having just attended "Preparing for Sea Level Rise in the Bay Area", in which SF Bay Area local governments are trying to plan for next 50-100 years, how to zone, where to build, where not to build, and how much it will cost (a lot), and how to deal with long SLRs. This is down-to-earth planning by people who actually have to do it in the real world.

Anyone dealing with sea level rise 100 years from now won't have cheap petroleum to help build sea walls (steel & concrete) or push dirt for dikes. Several of our bridges are very near sea level, as are both big airports, most sewage plants, many major roads, and big parts of Silicon Valley, and various residential areas.

There will be very unpleasant priority calls, and the politics will be very fierce, and this is one of the wealthier places on the planet...

By John Mashey (not verified) on 19 Apr 2008 #permalink

Does more catastrophism matter? Nobody seems to be *really* scared about the future (except J. Hansen?) - nobody will to anything meaningful to reduce carbon and/or ecological footprint. BTW, 8% of richest people emit about 50% of anthro CO2... so what?

Didn't the TAR think that Antarctica would remain in balance?

[From memory, the TAR has Ant as a contributor to decreasing sea level. Just like AR4 -W]

A separate quote from a report linked to by MT at In It, has Stern mentioning emissions rates and sink changes, so those may be the sections to look at? From memory the emissions rate is a little higher than expected (though that's CO2 alone, not GHG total)?

Not defending his position here, just trying to see where he's got it from. Might need to see the whole Reuters interview to follow his line though.

All of the studies of Antarctica summarized in AR4 Figure 4.18 show that it is currently losing ice. You're right that the projections show a contribution to decreasing sea level, which is yet another reason why the models cannot be trusted when it comes to ice (unless the models are right and the trend reverses itself).

An example of AR4 being more pessimistic is in the treatment of the carbon cycle. The A2 scenarios show additional warming of up to 1.5 degrees by 2100 if these factors are considered.

Stern uses the standard mainstream economic growth models -
usual sources -> IPCC -> Stern,
and on p183, footnote 35 it says:
annual GDP (per capita) growth of 1.9%, population growth 0.6%, or total GDP 2.5% growth.

The biophysical economists (like Charlie Hall or Robert Ayres/Benjamin Warr) use models that think *energy* (or rather work = energy*efficiency) is a stronger determinant of economic growth than labor or capital. Given Peak Oil & Gas, Ayres would predict that GDP flattens at some level depending on efficiency:
see p. 34 of Ayres.

At 2.5% CAGR, US GDP would be about 65X that of 1900 (to put on same scale as Ayres chart), i.e., 2X larger than peak of Ayres' best model.

Biophysical economics may be a weird minority position, or it may be a better model. If it's a better model, all these arguments about discount rates and exactly how much damage when isn't going to matter much if we haven't gone all-out for efficiency and building renewables soon. Pressure to burn coal to keep the lights on, and to do synfuels, will be enormous. See Charlie Hall's Balloon Graph to see how far we have to go.

[Not sure about the various econ models. But apologies for leaving your prior comment to languish in the queue for days -W]

By John Mashey (not verified) on 22 Apr 2008 #permalink

No problem - I thought the great bit-bucket had eaten it. Do consider taking a quick look at the Ayres & Hall stuff. I get very nervous with the standard models that seem to explain about half of economic growth, and leave the rest to some vague "technological progress", i.e., "Solow residual". If I saw the equivalent in a physics model, I'd be seriously worried. Ayres & co may or may not have a better approximation, but at least they seem to explain GDP better.

By John Mashey (not verified) on 23 Apr 2008 #permalink