----- Original Message ----- From: "Tom Adams" <[EMAIL PROTECTED]> Newsgroups: gmane.science.general.global-change To: "globalchange" <[email protected]> Sent: Monday, January 21, 2008 2:25 PM Subject: [Global Change: 2386] Re: Is it true?
On Jan 18, 5:55 pm, James Annan <[EMAIL PROTECTED]> wrote: > Don Libby wrote: > > Today I read a statement in the popular press that strikes me as absurd, > > but > > is it true? > > > "The world must reduce carbon emissions by 90% by 2030 to avert an > > ecosystem > > collapse..." > > This is probably based on the +2C "dangerous climate change": it is true > enough if you equate (the *risk* of) dangerous climate change with "an > ecosystem collapse". > Since this contrasts sharply with the opinion I had formed that shallow cuts now and deeper cuts later in the Century would be adequate to stabilize at or near 2x pre-industrial by 2100 (for example, the IS92c emission trajectory), I thought that perhaps some new science had cropped up in the last five years that escaped my attention and required me to get busy with my homework. A bit of further reading points me to "the Stern Review" as the authoritative source of opinion that sudden drastic reductions are necessary. An interesting critique is provided by William D. Nordhaus beginning on Page 101 of http://nordhaus.econ.yale.edu/dice_mss_091107_public.pdf ***begin quote*** How much and how fast should the globe reduce greenhouse-gas emissions? How should nations balance the costs of these reductions against the damages and dangers of climate change? The Stern Review answers these questions clearly and unambiguously: we need urgent, sharp, and immediate reductions in greenhouse-gas emissions. I am reminded of President Harry Truman's complaint that his economists would always say, on the one hand this and on the other hand that. He wanted a one-handed economist. The Stern Review is a President's or a Prime Minister's dream come true. It provides decisive answers instead of the dreaded conjectures, contingencies, and qualifications. However, a closer look reveals that there is indeed another hand to these answers. The Review's radical revision of the economics of climate change does not arise from any new economics, science, or modeling. Rather, it depends decisively on the assumption of a near-zero time discount rate combined with a specific utility function. The Review's unambiguous conclusions about the need for extreme immediate action will not survive the substitution of assumptions that are more consistent with today's market real interest and savings rates. Hence, the central questions about global-warming policy - how much, how fast, and how costly - remain open. The Review does not provide useful answers to these fundamental questions. ***end quote*** -dl --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups Global Change ("globalchange") newsgroup. Global Change is a public, moderated venue for discussion of science, technology, economics and policy dimensions of global environmental change. Posts will be admitted to the list if and only if any moderator finds the submission to be constructive and/or interesting, on topic, and not gratuitously rude. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/globalchange -~----------~----~----~----~------~----~------~--~---
