Causes of Climate Change Over the Past 1000 Years
14 Jul 2000-Science (American Association for the Advancement of Science)-Vol. 289, Iss: 5477, pp 270-277
TL;DR: A 21st-century global warming projection far exceeds the natural variability of the past 1000 years and is greater than the best estimate of global temperature change for the last interglacial.
Abstract: Recent reconstructions of Northern Hemisphere temperatures and climate forcing over the past 1000 years allow the warming of the 20th century to be placed within a historical context and various mechanisms of climate change to be tested. Comparisons of observations with simulations from an energy balance climate model indicate that as much as 41 to 64% of preanthropogenic (pre-1850) decadal-scale temperature variations was due to changes in solar irradiance and volcanism. Removal of the forced response from reconstructed temperature time series yields residuals that show similar variability to those of control runs of coupled models, thereby lending support to the models' value as estimates of low-frequency variability in the climate system. Removal of all forcing except greenhouse gases from the ∼1000-year time series results in a residual with a very large late-20th-century warming that closely agrees with the response predicted from greenhouse gas forcing. The combination of a unique level of temperature increase in the late 20th century and improved constraints on the role of natural variability provides further evidence that the greenhouse effect has already established itself above the level of natural variability in the climate system. A 21st-century global warming projection far exceeds the natural variability of the past 1000 years and is greater than the best estimate of global temperature change for the last interglacial.
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01 Jan 2007
TL;DR: Drafting Authors: Neil Adger, Pramod Aggarwal, Shardul Agrawala, Joseph Alcamo, Abdelkader Allali, Oleg Anisimov, Nigel Arnell, Michel Boko, Osvaldo Canziani, Timothy Carter, Gino Casassa, Ulisses Confalonieri, Rex Victor Cruz, Edmundo de Alba Alcaraz, William Easterling, Christopher Field, Andreas Fischlin, Blair Fitzharris.
Abstract: Drafting Authors: Neil Adger, Pramod Aggarwal, Shardul Agrawala, Joseph Alcamo, Abdelkader Allali, Oleg Anisimov, Nigel Arnell, Michel Boko, Osvaldo Canziani, Timothy Carter, Gino Casassa, Ulisses Confalonieri, Rex Victor Cruz, Edmundo de Alba Alcaraz, William Easterling, Christopher Field, Andreas Fischlin, Blair Fitzharris, Carlos Gay García, Clair Hanson, Hideo Harasawa, Kevin Hennessy, Saleemul Huq, Roger Jones, Lucka Kajfež Bogataj, David Karoly, Richard Klein, Zbigniew Kundzewicz, Murari Lal, Rodel Lasco, Geoff Love, Xianfu Lu, Graciela Magrín, Luis José Mata, Roger McLean, Bettina Menne, Guy Midgley, Nobuo Mimura, Monirul Qader Mirza, José Moreno, Linda Mortsch, Isabelle Niang-Diop, Robert Nicholls, Béla Nováky, Leonard Nurse, Anthony Nyong, Michael Oppenheimer, Jean Palutikof, Martin Parry, Anand Patwardhan, Patricia Romero Lankao, Cynthia Rosenzweig, Stephen Schneider, Serguei Semenov, Joel Smith, John Stone, Jean-Pascal van Ypersele, David Vaughan, Coleen Vogel, Thomas Wilbanks, Poh Poh Wong, Shaohong Wu, Gary Yohe
7,720 citations
TL;DR: In this article, the authors present the background and rationale for the new structure of CMIP, provides a detailed description of the DECK and CMIP6 historical simulations, and includes a brief introduction to the 21-CMIP6-Endorsed MIPs.
Abstract: . By coordinating the design and distribution of global climate model simulations of the past, current, and future climate, the Coupled Model Intercomparison Project (CMIP) has become one of the foundational elements of climate science. However, the need to address an ever-expanding range of scientific questions arising from more and more research communities has made it necessary to revise the organization of CMIP. After a long and wide community consultation, a new and more federated structure has been put in place. It consists of three major elements: (1) a handful of common experiments, the DECK (Diagnostic, Evaluation and Characterization of Klima) and CMIP historical simulations (1850–near present) that will maintain continuity and help document basic characteristics of models across different phases of CMIP; (2) common standards, coordination, infrastructure, and documentation that will facilitate the distribution of model outputs and the characterization of the model ensemble; and (3) an ensemble of CMIP-Endorsed Model Intercomparison Projects (MIPs) that will be specific to a particular phase of CMIP (now CMIP6) and that will build on the DECK and CMIP historical simulations to address a large range of specific questions and fill the scientific gaps of the previous CMIP phases. The DECK and CMIP historical simulations, together with the use of CMIP data standards, will be the entry cards for models participating in CMIP. Participation in CMIP6-Endorsed MIPs by individual modelling groups will be at their own discretion and will depend on their scientific interests and priorities. With the Grand Science Challenges of the World Climate Research Programme (WCRP) as its scientific backdrop, CMIP6 will address three broad questions: – How does the Earth system respond to forcing? – What are the origins and consequences of systematic model biases? – How can we assess future climate changes given internal climate variability, predictability, and uncertainties in scenarios? This CMIP6 overview paper presents the background and rationale for the new structure of CMIP, provides a detailed description of the DECK and CMIP6 historical simulations, and includes a brief introduction to the 21 CMIP6-Endorsed MIPs.
4,192 citations
TL;DR: It is found that an event like that of summer 2003 is statistically extremely unlikely, even when the observed warming is taken into account, and it is proposed that a regime with an increased variability of temperatures (in addition to increases in mean temperature) may be able to account for summer 2003.
Abstract: Instrumental observations1,2 and reconstructions3,4 of global and hemispheric temperature evolution reveal a pronounced warming during the past ∼150 years. One expression of this warming is the observed increase in the occurrence of heatwaves5,6. Conceptually this increase is understood as a shift of the statistical distribution towards warmer temperatures, while changes in the width of the distribution are often considered small7. Here we show that this framework fails to explain the record-breaking central European summer temperatures in 2003, although it is consistent with observations from previous years. We find that an event like that of summer 2003 is statistically extremely unlikely, even when the observed warming is taken into account. We propose that a regime with an increased variability of temperatures (in addition to increases in mean temperature) may be able to account for summer 2003. To test this proposal, we simulate possible future European climate with a regional climate model in a scenario with increased atmospheric greenhouse-gas concentrations, and find that temperature variability increases by up to 100%, with maximum changes in central and eastern Europe.
2,660 citations
Rutgers University1, Council of Scientific and Industrial Research2, Massachusetts Institute of Technology3, Commonwealth Scientific and Industrial Research Organisation4, Odense University5, Arizona State University6, University of California, Los Angeles7, University of New Hampshire8, Swedish University of Agricultural Sciences9, University of Hawaii10, University of British Columbia11, Alfred Wegener Institute for Polar and Marine Research12, Royal Swedish Academy of Sciences13
TL;DR: It is concluded that although natural processes can potentially slow the rate of increase in atmospheric CO2, there is no natural "savior" waiting to assimilate all the anthropogenically produced CO2 in the coming century.
Abstract: :Motivated by the rapid increase in atmospheric CO2 due to human activities since the Industrial Revolution, several international scientific research programs have analyzed the role of individual components of the Earth system in the global carbon cycle. Our knowledge of the carbon cycle within the oceans, terrestrial ecosystems, and the atmosphere is sufficiently extensive to permit us to conclude that although natural processes can potentially slow the rate of increase in atmospheric CO 2, there is no natural “savior” waiting to assimilate all the anthropogenically produced CO 2 in the coming century. Our knowledge is insufficient to describe the interactions between the components of the Earth system and the relationship between the carbon cycle and other biogeochemical and climatological processes. Overcoming this limitation requires a systems approach.
1,839 citations
TL;DR: Multiproxy reconstructions of monthly and seasonal surface temperature fields for Europe back to 1500 show that the late 20th- and early 21st-century European climate is very likely (>95% confidence level) warmer than that of any time during the past 500 years.
Abstract: Multiproxy reconstructions of monthly and seasonal surface temperature fields for Europe back to 1500 show that the late 20th- and early 21st-century European climate is very likely (>95% confidence level) warmer than that of any time during the past 500 years. This agrees with findings for the entire Northern Hemisphere. European winter average temperatures during the period 1500 to 1900 were reduced by ∼0.5°C (0.25°C for annual mean temperatures) compared to the 20th century. Summer temperatures did not experience systematic century-scale cooling relative to present conditions. The coldest European winter was 1708/1709; 2003 was by far the hottest summer.
1,665 citations
References
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TL;DR: In this article, the authors attempt hemispheric temperature reconstructions with proxy data networks for the past millennium, focusing not just on the reconstructions, but the uncertainties therein, and important caveats.
Abstract: Building on recent studies, we attempt hemispheric temperature reconstructions with proxy data networks for the past millennium. We focus not just on the reconstructions, but the uncertainties therein, and important caveats. Though expanded uncertainties prevent decisive conclusions for the period prior to AD 1400, our results suggest that the latter 20th century is anomalous in the context of at least the past millennium. The 1990s was the warmest decade, and 1998 the warmest year, at moderately high levels of confidence. The 20th century warming counters a millennial-scale cooling trend which is consistent with long-term astronomical forcing.
1,742 citations
Book•
01 Jan 1992
TL;DR: In this paper, the authors present an update of the emissions scenarios for the United Nations Environment Programme (UNEP), which is based on the results of the 1992 International Journal of Distributed Sensor Networks (JDSN).
Abstract: Foreword Preface 1992 Supplement A. Greenhouse gases A1. Sources and sinks A2. Radiative forcing of climate A3. Emissions scenarios for IPCC: an update B. Climate modelling, climate prediction and model validation C. Observed climate variability and change Annex Appendices. Sponsored jointly by the World Meteorological Organization and the United Nations Environment Programme
1,733 citations
TL;DR: In this article, a spatially resolved global reconstructions of annual surface temperature patterns over the past six centuries are based on the multivariate calibration of widely distributed high-resolution proxy climate indicators.
Abstract: Spatially resolved global reconstructions of annual surface temperature patterns over the past six centuries are based on the multivariate calibration of widely distributed high-resolution proxy climate indicators. Time-dependent correlations of the reconstructions with time-series records representing changes in greenhouse-gas concentrations, solar irradiance, and volcanic aerosols suggest that each of these factors has contributed to the climate variability of the past 400 years, with greenhouse gases emerging as the dominant forcing during the twentieth century. Northern Hemisphere mean annual temperatures for three of the past eight years are warmer than any other year since (at least) ad 1400.
1,720 citations
TL;DR: The surface air temperature record of the past 150 years, considering the homogeneity of the basic data and the standard errors of estimation of the average hemispheric and global estimates, is reviewed in this article.
Abstract: We review the surface air temperature record of the past 150 years, considering the homogeneity of the basic data and the standard errors of estimation of the average hemispheric and global estimates. We present global fields of surface temperature change over the two 20-year periods of greatest warming this century, 1925–1944 and 1978–1997. Over these periods, global temperatures rose by 0.37° and 0.32°C, respectively. The twentieth-century warming has been accompanied by a decrease in those areas of the world affected by exceptionally cool temperatures and to a lesser extent by increases in areas affected by exceptionally warm temperatures. In recent decades there have been much greater increases in night minimum temperatures than in day maximum temperatures, so that over 1950–1993 the diurnal temperature range has decreased by 0.08°C per decade. We discuss the recent divergence of surface and satellite temperature measurements of the lower troposphere and consider the last 150 years in the context of the last millennium. We then provide a globally complete absolute surface air temperature climatology on a 1° × 1° grid. This is primarily based on data for 1961–1990. Extensive interpolation had to be undertaken over both polar regions and in a few other regions where basic data are scarce, but we believe the climatology is the most consistent and reliable of absolute surface air temperature conditions over the world. The climatology indicates that the annual average surface temperature of the world is 14.0°C (14.6°C in the Northern Hemisphere (NH) and 13.4°C for the Southern Hemisphere). The annual cycle of global mean temperatures follows that of the land-dominated NH, with a maximum in July of 15.9°C and a minimum in January of 12.2°C.
1,369 citations
Book•
09 Feb 2011
TL;DR: In this paper, the authors present a Chronology of large-volume Holocene Eruptions Fatalities and Evacuations Preliminary List of Pleistocene Volcanoes Preliminary list of Large-Volume Pleistogenic Eruption Gazetteer References VOLCANO DATA Volcano Name Subregion Latitude and Longitude Elevation Population Rock Type Type (Morphology) Volcano Number Status ERUPTION DATA Area of Activity Dates: Start and Stop Uncertainties Dating Techniques Duration Eruptive Characteristics Volcanic Explosivity Index (VEI) Volume of Products (Vol
Abstract: Preface DATA CRITERIA AND CONTEXT INTRODUCTION Previous Summaries Sources Years Covered Maps and Regional Numbering Scheme DATA TABLE SUMMARIES Directory Chronology Large-Volume Holocene Eruptions Fatalities and Evacuations Preliminary List of Pleistocene Volcanoes Preliminary List of Large-Volume Pleistocene Eruptions Gazetteer References VOLCANO DATA Volcano Name Subregion Latitude and Longitude Elevation Population Rock Type Type (Morphology) Volcano Number Status ERUPTION DATA Area of Activity Dates: Start and Stop Uncertainties Dating Techniques Duration Eruptive Characteristics Volcanic Explosivity Index (VEI) Volume of Products (Vol L/T) HISTORICAL RECORD: TRENDS AND CAUTIONS Volcanoes and Humans Volcanoes and Aircraft Volcanic Processes Volcanism: Magnitude, Frequency, and Global Impacts Durations and Paroyxyms Episodicity and Periodicity Intervals between Eruptions and Associated Hazard Implications Conclusions References DIRECTORY OF VOLCANOES Europe to Caucasus (01) Africa & Red Sea (02) Middle East & Indian Ocean (03) New Zealand to Fiji (04) Melanesia & Australia (05) Indonesia & Andaman Is (06) Philippines & SE Asia (07) Japan, Taiwan & Marianas (08) Kuriles, Kamchatka & Mainland Asia (09 &10) Alaska (11) Canada & Western USA (12) Pacific Ocean (13) Mexico & Central America (14) South America (15) West Indies (16) Iceland & Arctic Ocean (17) Atlantic Ocean (18) Antarctica & S Sandwich Islands (19) CHRONOLOGY OF ERUPTIONS LARGE-VOLUME HOLOCENE ERUPTIONS Explosive Eruptions Effusive Eruptions FATALITIES AND EVACUATIONS Fatalities Evacuations PRELIMINARY LIST Of PLEISTOCENE VOLCANOES PRELIMINARY LIST Of LARGE-VOLUME PLEISTOCENE ERUPTIONS COLOR PHOTO SECTION GAZETTER REFERENCES
1,261 citations