###################################################################### "steady state economics"
http://www.pik-potsdam.de/news/press-releases/4-degrees-briefing-for-the-world-bank-the-risks-of-a-future-without-climate-policy Humankind’s emissions of greenhouse gases are breaking new records every year. Hence we’re on a path towards 4-degree [Celsius, or hotter by 7.2 degrees Fahrenheight] global warming probably as soon as by the end of this century. This would mean a world of risks beyond the experience of our civilization ..affecting hundreds of millions of people, and regional [crop] yield failures impacting global food security" “The planetary machinery tends to be jumpy, this is to respond disproportionately to disruptions that come with the manmade greenhouse effect,” PIK’s director Hans Joachim Schellnhuber points out. “If we venture far beyond the 2-degree guardrail, towards 4 degrees, we risk crossing tipping points in the Earth system.” World Bank President Jim Yong Kim who ..has personally been briefed on the..report [and said] "A 4-degree warmer world can, and must be, avoided – we need to hold warming below 2 degrees. Lack of action on climate change threatens to make the world our children inherit a completely different world than we are living in today. Climate change is one of the biggest single challenges facing development, and we need to assume the moral responsibility to take action on behalf of future generations" The poorest in the world are those that will be hit hardest, making development without climate policy almost impossible, the researchers conclude. --Results of a report for the World Bank, conducted by the Potsdam Institute for Climate Impact Research (PIK) and Climate Analytics in Berlin. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - "Even with the current..commitments and pledges fully implemented, there is roughly a 20 percent likelihood of exceeding 4°C by 2100. If they are not met, a warming of 4°C could occur as early as the 2060s. Such a warming level..would not be the end point: a further warming [past 2100] to levels over 6°C, with several meters of sea-level rise, would likely occur over the following centuries." from the pdf of the executive summary - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - "In Amazonia, forest fires could as much as double by 2050 with warming of approximately 1.5°C to 2°C above preindustrial levels" while expected changes "would be..even more severe in a [world warmer by] 4C" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - The full scope of damages in a 4°C world has not been assessed to date. Large-scale and disruptive changes in the Earth system are generally not included in modeling exercises, and rarely in impact assessments. As global warming approaches and exceeds 2°C, the risk of crossing thresholds of nonlinear tipping elements in the Earth system, with abrupt climate change impacts and unprec- edented high-temperature climate regimes, increases. Examples include the disintegration of the West Antarctic ice sheet leading to more rapid sea-level rise than projected in this analysis or large-scale Amazon dieback drastically affecting ecosystems.. ====================================================================== C= (5/9)(F-32) thus, F= BUT (change-in-F) = (5/9)(change-in-C) Example: "hotter by 0 F means hotter by ____C? clearly, also 0. So can't use first pair of formulas ###################################################################### if on deserted island people are just as happy this year to consume 5% less wood and thereby let the trees grow back more, is that neutral, good, or bad? Looked at on the purely physical level, clearly, if they are (by assumption) just as happy.....then... ######################################################################
The new research involved 400 runs of the model with each run using slight variations in input parameters, selected so that each run has about an equal probability of being correct based on present observations and knowledge. Other research groups have estimated the probabilities of various outcomes, based on variations in the physical response of the climate system itself. But the MIT model is the only one that interactively includes detailed treatment of possible changes in human activities as well - such as the degree of economic growth, with its associated energy use, in different countries.
Study co-author Ronald Prinn, the co-director of the Joint Program and director of MIT's Center for Global Change Science, .. in the peer-reviewed literature, the MIT model, unlike any other, looks in great detail at the effects of economic activity coupled with the effects of atmospheric, oceanic and biological systems.
The new projections, published this month in the American Meteorological Society's Journal of Climate, indicate a median probability of surface warming of 5.2 degrees Celsius by 2100, with a 90% probability range of 3.5 to 7.4 degrees. ..he difference is caused by several factors rather than any single big change. Among these are improved economic modeling and newer economic data showing less chance of low emissions than had been projected in the earlier scenarios. Other changes include accounting for the past masking of underlying warming by the cooling induced by 20th century volcanoes, and for emissions of soot, which can add to the warming effect. In addition, measurements of deep ocean temperature rises, which enable estimates of how fast heat and carbon dioxide are removed from the atmosphere and transferred to the ocean depths, imply lower transfer rates than previously estimated.
..While the outcomes in the "no policy" projections now look much worse than before, there is less change from previous work in the projected outcomes if STRONG policies are put in place now to drastically curb greenhouse gas emissions [my emphasis, their word; elsewhere, they use the phrase "agressive policy change "
"To my knowledge, this is indeed the most exhaustive end-to-end analysis of climate change impacts yet performed," notes Michael Mann, a climatologist at Penn State University and also an IPCC author. " http://usatoday30.usatoday.com/tech/science/environment/2009-05-20-global-warming_N.htm?imw=Y ]
["substantial policy change." http://web.mit.edu/newsoffice/2009/roulette-0519.html#]
.."There's no way the world can or should take these risks," Prinn says. And the odds indicated by this modeling may actually understate the problem, because the model does not fully incorporate other positive feedbacks that can occur, for example, if increased temperatures caused a large-scale melting of permafrost in arctic regions and subsequent release of large quantities of methane, a very potent greenhouse gas. Including that feedback "is just going to make it worse," Prinn says.
...Beyond this, "we do the research, and let the results fall where they may," he says. Since there are so many uncertainties, especially with regard to what human beings will choose to do and how large the climate response will be, "we don't pretend we can do it accurately. Instead, we do these 400 runs and look at the spread of the odds."
The first draft of the paper had said the vast majority of such analyses should carry the following label: “WARNING: to be used ONLY for cost-benefit analysis of non-extreme climate change possibilities. NOT INTENDED to cover welfare evaluation of extreme tail possibilities, for which a complete accounting might produce ARBITRARILY DIFFERENT welfare outcomes.”
The final version(http://www.economics.harvard.edu/faculty/weitzman/files/REStatFINAL.pdf) , “On Modeling and Interpreting the Economics of Catastrophic Climate Change,” eliminated that disclaimer, but replaced it with a longer statement that is equally devastating (see below).
For Weitzman, disaster is a temperature change of > 6°C (11°F) in a century, as he explains in an earlier paper on the Stern Review on the economics of climate change: """With roughly 3% IPCC-4 probability, we will “consume” a terra incognita biosphere within a hundred years whose mass species extinctions, radical alterations of natural environments, and other extreme outdoor consequences of a different planet will have been triggered by a geologically-instantaneous temperature change that is signicantly larger than what separates us now from past ice ages."""
Weitzman says the IPCC Fourth Assessment gives the probability of such an “extreme” temperature change as 3%, and that “to ignore or suppress the signi…ficance of rare tail disasters is to ignore or suppress what economic theory is telling us loudly and clearly is potentially the most important part of the analysis” — more important than the discount rate.
For me, what is especially important about Weitzman’s analysis is that the science is now crystal clear that there is far greater chance than 3% chance we will have a total warming of 6°C in a century or so if we don’t reverse emissions trends soon. Indeed, there is a very high chance we will see above 5.5°C warming or more this century according to the prestigious Hadley Center (see “Hadley Center: Catastrophic 5.5-7°C warming by 2100 on current emissions path“). Same for the normally staid and conservative International Energy Agency, which noted in its most recent World Energy, “Without a change in policy, the world is on a path for a rise in global temperature of up to 6°C.” In fact, a close reading of the 2007 IPCC report makes clear that absent a very strong and immediate emissions reduction effort, we are aiming right at 1000 ppm or higher — which is a 5°C warming or higher this century — as I explained in my recent Nature online article.
[Note: Let me be clear that 550 ppm to 750 ppm or a 3°C to 4°C total warming from preindustrial levels -- which takes us to the same temperature the planet had the last time sea levels were 80 to 250 feet higher -- would be an unmitigated catastrophe for the planet -- that is Hansen's point. In any case, if we get that warm, the defrosting of the permafrost and or one (or more) of the myriad other amplifying feedbacks will probably take us to 6°C warming within a few decades (see Study: Water-vapor feedback is "strong and positive," so we face "warming of several degrees Celsius").]
the mainstream economic policy think tank — Resources for the Future (RFF) — wrote a major report, “An Even Sterner Review,” that concluded, “we find no strong objections to the discounting assumptions adopted in the Stern Review” (a point I have made, also, based on Quiggin). It also concluded Stern could have used “rising relative prices” from future scarcity to get the same result. The RFF report pointed out: If we were to combine the low discount rates in the Stern Review with rising relative prices, the conclusions would favor even higher levels of abatement. This would in fact lead us to consider some of the levels of carbon content that Stern deems unrealistic, that is, aiming for a target of less than 450 ppm CO2 equivalents.
Weitzman still thinks that Stern is mostly right for the “wrong reasons” — because the “the implications of large consequences with small probabilities” — like the many scenarios of catastrophic climate change (ice sheet instability, tundra melting) — matter more than the choice of discount rate.
In short, cost-benefit analyses (CBAs) are garbage in garbage out (GIGO), or perhaps, mainstream economics in, garbage out (MEIGO). Weitzman continues by explaining the uselessness of conventional “Integrated Assessment Model”s (IAMs) in the face of his central analytical point, which he calls the Dismal Theorem or DT (first emphasis below in original):
Even just acknowledging more openly the incredible magnitude of the deep structural uncertainties that are involved in climate-change analysis –and explaining better to policy makers that the arti…cial crispness conveyed by conventional IAM-based CBAs here is especially and unusually misleading compared with more-ordinary non-climate-change CBA situations –might go a long way towards elevating the level of public discourse concerning what to do about global warming. All of this is naturally unsatisfying and not what economists are used to doing, but t in rare situations like climate change where DT applies we may be deluding ourselves and others with misplaced concreteness ss if we think that we are able to deliver anything much more precise than this with even the biggest and most-detailed climate-change IAMs as currently constructed and deployed.
Weitz: "Perhaps in the end the climate-change economist can help most by not presenting a cost-bene…fit estimate for what is inherently a fat-tailed situation with potentially unlimited downside exposure as if it is accurate and objective –and perhaps not even presenting the analysis as if it is an approximation to something that is accurate and objective –but instead by stressing somewhat more openly the fact that such an estimate might conceivably be arbitrarily inaccurate depending upon what is subjectively assumed about the high-temperature damages function along with assumptions about the fatness of the tails and/or where they have been cut off."
romm: The proper damage function is thus not fat-tailed — it is completely open-ended, like an S-curve. That is especially true because of the irreversibility issue. If we don’t keep concentrations below a threshold like 450 ppm (or lower), we face the prospect of essentially incalculably large damages that might well get worse and worse for centuries...What exactly is the cost of sea level in 2100 of 5 feet rising therafter 10 inches or more a decade (potentially reaching 20 inches a decade or higher) until the planet is ice free in several centuries and sea levels are 250 feet higher?....If any of you economists out there have a plausible net present value of the cost of that outcome, I’d love to see it. Same for one third of the planet becoming a permanent desert and large parts of the ocean becoming hot, acidic dead zones. .
as others noted: the Precautionary Principle