根據(jù)對氣候?qū)＜业囊豁?xiàng)調(diào)查，如果而二氧化碳排放繼續(xù)增加,，人類導(dǎo)致的全球變暖可能讓地球的氣候在200年內(nèi)達(dá)到一個傾覆點(diǎn)的幾率大約50%,?？茖W(xué)家最近開始把傾覆點(diǎn)定義為影響地球至少一半并且持續(xù)數(shù)十年的根本性的氣候變化,。M. Granger Morgan及其同事對14位氣候科學(xué)家進(jìn)行了一場面對面的訪談，據(jù)該研究說,，這些科學(xué)家代表了一系列的主流觀點(diǎn),。
在訪談期間，向這些專家提供了到2200年CO2增加的低,、中,、高軌跡——所有這些軌跡都在IPCC的最新預(yù)測中，然后讓他們提出每一種情景迫使氣候系統(tǒng)越過傾覆點(diǎn)的概率,。這組作者報(bào)告說,，對于高軌跡，14位專家中的13位回答說可能性大約50%,，而10位專家說可能性大于等于75%,。這組作者說，這種可能改變氣候的CO2情景盡管是高的，但是它仍然位于IPCC提供的情景范圍之內(nèi),。(生物谷www.bioon.net)
生物谷推薦原文出處：
PNAS doi: 10.1073/pnas.0908906107
Expert judgments about transient climate response to alternative future trajectories of radiative forcing
Kirsten Zickfelda,2, M. Granger Morganb,1, David J. Framec, and David W. Keithd
aSchool of Earth and Ocean Sciences, University of Victoria, Victoria, BC V8P 5C2, Canada;
bDepartment of Engineering and Public Policy, Carnegie Mellon University, Pittsburgh, PA 15213;
cSmith School of Enterprise and the Environment and Department of Physics, University of Oxford, Oxford OX1 2BQ, UK; and
dDepartment of Chemical and Petroleum Engineering, University of Calgary, Calgary, AB T2N 1N4, Canada
There is uncertainty about the response of the climate system to future trajectories of radiative forcing. To quantify this uncertainty we conducted face-to-face interviews with 14 leading climate scientists, using formal methods of expert elicitation. We structured the interviews around three scenarios of radiative forcing stabilizing at different levels. All experts ranked “cloud radiative feedbacks” as contributing most to their uncertainty about future global mean temperature change, irrespective of the specified level of radiative forcing. The experts disagreed about the relative contribution of other physical processes to their uncertainty about future temperature change. For a forcing trajectory that stabilized at 7 Wm-2 in 2200, 13 of the 14 experts judged the probability that the climate system would undergo, or be irrevocably committed to, a “basic state change” as ≥0.5. The width and median values of the probability distributions elicited from the different experts for future global mean temperature change under the specified forcing trajectories vary considerably. Even for a moderate increase in forcing by the year 2050, the medians of the elicited distributions of temperature change relative to 2000 range from 0.8–1.8?°C, and some of the interquartile ranges do not overlap. Ten of the 14 experts estimated that the probability that equilibrium climate sensitivity exceeds 4.5?°C is > 0.17, our interpretation of the upper limit of the “likely” range given by the Intergovernmental Panel on Climate Change. Finally, most experts anticipated that over the next 20 years research will be able to achieve only modest reductions in their degree of uncertainty.
