An assessment of Earth's climate sensitivity using multiple lines of evidence
Steven C. Sherwood,Mark J. Webb,James D. Annan,Kyle C. Armour,Piers M. Forster,Julia C. Hargreaves,Gabriele C. Hegerl,S A Klein,Kate Marvel,Kate Marvel,Eelco J. Rohling,Eelco J. Rohling,Masahiro Watanabe,Timothy Andrews,Pascale Braconnot,Christopher S. Bretherton,Gavin L. Foster,Zeke Hausfather,A. S. von der Heydt,Reto Knutti,Thorsten Mauritsen,Joel R. Norris,Cristian Proistosescu,Maria Rugenstein,Gavin A. Schmidt,Katarzyna B. Tokarska,Mark D. Zelinka +26 more
TLDR
Evidence relevant to Earth's equilibrium climate sensitivity per doubling of atmospheric CO2, characterized by an effective sensitivity S, is assessed, using a Bayesian approach to produce a probability density function for S given all the evidence, and promising avenues for further narrowing the range are identified.Abstract:
We assess evidence relevant to Earth's equilibrium climate sensitivity per doubling of atmospheric CO2, characterized by an effective sensitivity S. This evidence includes feedback process understanding, the historical climate record, and the paleoclimate record. An S value lower than 2 K is difficult to reconcile with any of the three lines of evidence. The amount of cooling during the Last Glacial Maximum provides strong evidence against values of S greater than 4.5 K. Other lines of evidence in combination also show that this is relatively unlikely. We use a Bayesian approach to produce a probability density function (PDF) for S given all the evidence, including tests of robustness to difficult-to-quantify uncertainties and different priors. The 66% range is 2.6-3.9 K for our Baseline calculation and remains within 2.3-4.5 K under the robustness tests; corresponding 5-95% ranges are 2.3-4.7 K, bounded by 2.0-5.7 K (although such high-confidence ranges should be regarded more cautiously). This indicates a stronger constraint on S than reported in past assessments, by lifting the low end of the range. This narrowing occurs because the three lines of evidence agree and are judged to be largely independent and because of greater confidence in understanding feedback processes and in combining evidence. We identify promising avenues for further narrowing the range in S, in particular using comprehensive models and process understanding to address limitations in the traditional forcing-feedback paradigm for interpreting past changes.read more
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Why is climate sensitivity so unpredictable
Gerard H. Roe,Marcia B. Baker +1 more
TL;DR: It is shown that the breadth of the distribution and, in particular, the probability of large temperature increases are relatively insensitive to decreases in uncertainties associated with the underlying climate processes.
Journal Article
Global glacier mass changes and their contributions to sea-level rise from 1961 to 2016
Michael Zemp,Matthias Huss,Matthias Huss,Emmanuel Thibert,Nicolas Eckert,Robert McNabb,Jacqueline Huber,Martina Barandun,Horst Machguth,Horst Machguth,Samuel U. Nussbaumer,Isabelle Gärtner-Roer,Laura Thomson,Frank Paul,Fabien Maussion,Stanislav Kutuzov,J. Graham Cogley +16 more
TL;DR: The largest collection so far of glaciological and geodetic observations suggests that glaciers contributed about 27 millimetres to sea-level rise from 1961 to 2016, at rates of ice loss that could see the disappearance of many glaciers this century.
Journal ArticleDOI
GISS-E2.1: Configurations and Climatology.
Maxwell Kelley,Gavin A. Schmidt,Larissa Nazarenko,Larissa Nazarenko,Susanne E. Bauer,Reto Ruedy,Gary L. Russell,Andrew S. Ackerman,Igor Aleinov,Igor Aleinov,Michael Bauer,Michael Bauer,Rainer Bleck,Rainer Bleck,Vittorio Canuto,G. Cesana,G. Cesana,Y. Cheng,Y. Cheng,Thomas Clune,Ben I. Cook,Carlos A. Cruz,Anthony D. Del Genio,Gregory S. Elsaesser,Gregory S. Elsaesser,Greg Faluvegi,Greg Faluvegi,Nancy Y. Kiang,Daehyun Kim,Andrew A. Lacis,Anthony Leboissetier,Allegra N. LeGrande,Ken K. Lo,John Marshall,Elaine Matthews,Sonali McDermid,Keren Mezuman,Keren Mezuman,Ron L. Miller,Lee T. Murray,Valdar Oinas,Clara Orbe,Carlos Pérez García-Pando,Carlos Pérez García-Pando,J. P. Perlwitz,Michael J. Puma,Michael J. Puma,David Rind,Anastasia Romanou,Drew Shindell,Shan Sun,N. Tausnev,Kostas Tsigaridis,Kostas Tsigaridis,George Tselioudis,Ensheng Weng,Ensheng Weng,Jingbo Wu,Jingbo Wu,Mao-Sung Yao +59 more
TL;DR: There have been specific improvements in representations of modes of variability (such as the Madden‐Julian Oscillation and other modes in the Pacific) and significant improvements in the simulation of the climate of the Southern Oceans, including sea ice.
Time-varying climate sensitivity from regional feedbacks
TL;DR: In this article, the global climate sensitivity with respect to forcing is defined in terms of the global radiative response per degree of global annual mean surface temperature change, and a reformulation of global climate feedback is proposed, providing a clear physical insight into this behavior.
Journal ArticleDOI
Climate model projections from the Scenario Model Intercomparison Project (ScenarioMIP) of CMIP6
Claudia Tebaldi,Kevin Debeire,Veronika Eyring,Veronika Eyring,Erich M. Fischer,John C. Fyfe,Pierre Friedlingstein,Pierre Friedlingstein,Reto Knutti,Jason Lowe,Jason Lowe,Brian C. O'Neill,Brian C. O'Neill,Benjamin Sanderson,Detlef P. van Vuuren,Keywan Riahi,Malte Meinshausen,Zebedee Nicholls,Katarzyna B. Tokarska,George C. Hurtt,Elmar Kriegler,Jean-Francois Lamarque,Gerald A. Meehl,Richard H. Moss,Susanne E. Bauer,Olivier Boucher,Victor Brovkin,Victor Brovkin,Young-Hwa Byun,Martin Dix,Silvio Gualdi,Huan Guo,Jasmin G. John,Slava Kharin,Young Ho Kim,Young Ho Kim,Tsuyoshi Koshiro,Libin Ma,Dirk Jan Leo Oliviè,Swapna Panickal,Fangli Qiao,Xinyao Rong,Nan Rosenbloom,Martin Schupfner,Roland Séférian,Alistair Sellar,Tido Semmler,Xiaoying Shi,Zhenya Song,Christian Steger,Ronald J. Stouffer,Neil C. Swart,Kaoru Tachiiri,Qi Tang,Hiroaki Tatebe,Aurore Voldoire,Evgeny Volodin,Klaus Wyser,Xiaoge Xin,Shuting Yang,Yongqiang Yu,Tilo Ziehn +61 more
TL;DR: In this paper, the authors present a range of its outcomes by synthesizing results from the participating global coupled Earth system models for concentration driven simulations, focusing mainly on the analysis of strictly geophysical outcomes: mainly global averages and spatial patterns of change for surface air temperature and precipitation.
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