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Anais Orsi

Bio: Anais Orsi is an academic researcher from Université Paris-Saclay. The author has contributed to research in topics: Ice core & Antarctic ice sheet. The author has an hindex of 23, co-authored 55 publications receiving 3109 citations. Previous affiliations of Anais Orsi include University of California, San Diego & Centre national de la recherche scientifique.
Topics: Ice core, Antarctic ice sheet, Firn, Snow, Ice sheet


Papers
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Journal ArticleDOI
Dorthe Dahl-Jensen, Mary R. Albert1, Ala Aldahan2, Nobuhiko Azuma3, David Balslev-Clausen4, Matthias Baumgartner, Ann-Marie Berggren2, Matthias Bigler, Tobias Binder5, Thomas Blunier, J. C. Bourgeois6, Edward J. Brook7, Susanne L Buchardt4, Christo Buizert, Emilie Capron, Jérôme A Chappellaz8, J. Chung9, Henrik Clausen4, Ivana Cvijanovic4, Siwan M. Davies10, Peter D. Ditlevsen4, Olivier Eicher11, Hubertus Fischer11, David A. Fisher6, L. G. Fleet12, Gideon Gfeller11, Vasileios Gkinis4, Sivaprasad Gogineni13, Kumiko Goto-Azuma14, Aslak Grinsted4, H. Gudlaugsdottir15, Myriam Guillevic4, S. B. Hansen4, Martin Hansson16, Motohiro Hirabayashi14, S. Hong, S. D. Hur9, Philippe Huybrechts17, Christine S. Hvidberg4, Yoshinori Iizuka16, Theo M. Jenk4, Sigfus J Johnsen4, Tyler R. Jones18, Jean Jouzel, Nanna B. Karlsson4, Kenji Kawamura14, Kaitlin M. Keegan1, E. Kettner4, Sepp Kipfstuhl19, Helle Astrid Kjær4, Michelle Koutnik20, Takayuki Kuramoto14, Peter Köhler19, Thomas Laepple19, Amaelle Landais, Peter L. Langen4, L. B. Larsen4, Daiana Leuenberger11, Markus Leuenberger, Carl Leuschen13, J. Li13, Vladimir Ya. Lipenkov21, Patricia Martinerie8, Olivia J. Maselli22, Valérie Masson-Delmotte, Joseph R. McConnell22, Heinrich Miller19, Olivia Mini11, A. Miyamoto23, M. Montagnat-Rentier24, Robert Mulvaney12, Raimund Muscheler, Anais Orsi25, John Paden13, Christian Panton4, Frank Pattyn26, Jean-Robert Petit8, K. Pol, Trevor Popp, G. Possnert, Frédéric Prié, M. Prokopiou, Aurélien Quiquet24, Sune Olander Rasmussen4, Dominique Raynaud8, J. Ren, C. Reutenauer4, Catherine Ritz8, Thomas Röckmann, Jean Rosen7, Mauro Rubino, Oleg Rybak19, Denis Samyn2, Célia Sapart27, Adrian Schilt28, A. Schmidt4, Jakob Schwander11, Simon Schüpbach, Inger K Seierstad, Jeffrey P. Severinghaus25, Simon G. Sheldon4, Sebastian B. Simonsen4, Jesper Sjolte, Anne M. Solgaard4, Todd Sowers, Peter Sperlich, Hans Christian Steen-Larsen29, Konrad Steffen30, J. P. Steffensen31, Daniel Steinhage19, Thomas F. Stocker, C. Stowasser18, A. S. Sturevik32, W. T. Sturges33, Arny E. Sveinbjörnsdottir29, A. Svensson30, Jean-Louis Tison31, J. Uetake34, Paul Vallelonga, R. S. W. van de Wal19, G. van der Wel11, Bruce H. Vaughn4, Bo Møllesøe Vinther2, E. Waddington35, Anna Wegner, Ilka Weikusat19, James W. C. White26, Frank Wilhelms19, Mai Winstrup4, Emmanuel Witrant, Eric W. Wolff11, C. Xiao, J. Zheng36 
24 Jan 2013-Nature
TL;DR: In this paper, the North Greenland Eemian Ice Drilling (NEEM) ice core was extracted from folded Greenland ice using globally homogeneous parameters known from dated Greenland and Antarctic ice-core records.
Abstract: Efforts to extract a Greenland ice core with a complete record of the Eemian interglacial (130,000 to 115,000 years ago) have until now been unsuccessful. The response of the Greenland ice sheet to the warmer-than-present climate of the Eemian has thus remained unclear. Here we present the new North Greenland Eemian Ice Drilling ('NEEM') ice core and show only a modest ice-sheet response to the strong warming in the early Eemian. We reconstructed the Eemian record from folded ice using globally homogeneous parameters known from dated Greenland and Antarctic ice-core records. On the basis of water stable isotopes, NEEM surface temperatures after the onset of the Eemian (126,000 years ago) peaked at 8 +/- 4 degrees Celsius above the mean of the past millennium, followed by a gradual cooling that was probably driven by the decreasing summer insolation. Between 128,000 and 122,000 years ago, the thickness of the northwest Greenland ice sheet decreased by 400 +/- 250 metres, reaching surface elevations 122,000 years ago of 130 +/- 300 metres lower than the present. Extensive surface melt occurred at the NEEM site during the Eemian, a phenomenon witnessed when melt layers formed again at NEEM during the exceptional heat of July 2012. With additional warming, surface melt might become more common in the future.

546 citations

Dorthe Dahl-Jensen, Mary R. Albert, Ala Aldahan, Nobuhiko Azuma, David Balslev-Clausen, Matthias Baumgartner, Ann-Marie Berggren, Matthias Bigler, Tobias Binder, Thomas Blunier, J. C. Bourgeois, Edward J. Brook, Susanne L Buchardt, Christo Buizert, Emilie Capron, Jérôme A Chappellaz, J. Chung, Henrik Clausen, Ivana Cvijanovic, Siwan M. Davies, Peter D. Ditlevsen, Olivier Eicher, Hubertus Fischer, David A. Fisher, L. G. Fleet, Gideon Gfeller, Vasileios Gkinis, Sivaprasad Gogineni, Kumiko Goto-Azuma, Aslak Grinsted, H. Gudlaugsdottir, Myriam Guillevic, S. B. Hansen, Martin Hansson, Motohiro Hirabayashi, S. Hong, S. D. Hur, Philippe Huybrechts, Christine S. Hvidberg, Yoshinori Iizuka, Theo M. Jenk, Sigfus J Johnsen, Tyler R. Jones, Jean Jouzel, Nanna B. Karlsson, Kenji Kawamura, Kaitlin M. Keegan, E. Kettner, Sepp Kipfstuhl, Helle Astrid Kjær, Michelle Koutnik, Takayuki Kuramoto, Peter Köhler, Thomas Laepple, Amaelle Landais, Peter L. Langen, L. B. Larsen, Daiana Leuenberger, Markus Leuenberger, Carl Leuschen, J. Li, Vladimir Ya. Lipenkov, Patricia Martinerie, Olivia J. Maselli, Valérie Masson-Delmotte, Joseph R. McConnell, Heinrich Miller, Olivia Mini, A. Miyamoto, M. Montagnat-Rentier, Robert Mulvaney, Raimund Muscheler, Anais Orsi, John Paden, Christian Panton, Frank Pattyn, Jean-Robert Petit, K. Pol, Trevor Popp, G. Possnert, Frédéric Prié, M. Prokopiou, Aurélien Quiquet, Sune Olander Rasmussen, Dominique Raynaud, J. Ren, C. Reutenauer, Catherine Ritz, Thomas Röckmann, Jean Rosen, Mauro Rubino, Oleg Rybak, Denis Samyn, Célia Sapart, Adrian Schilt, A. Schmidt, Jakob Schwander, Simon Schüpbach, Inger K Seierstad, Jeffrey P. Severinghaus, Simon G. Sheldon, Sebastian B. Simonsen, Jesper Sjolte, Anne M. Solgaard, Todd Sowers, Peter Sperlich, Hans Christian Steen-Larsen, Konrad Steffen, J. P. Steffensen, Daniel Steinhage, Thomas F. Stocker, C. Stowasser, A. S. Sturevik, W. T. Sturges, Arny E. Sveinbjörnsdottir, A. Svensson, Jean-Louis Tison, J. Uetake, Paul Vallelonga, R. S. W. van de Wal, G. van der Wel, Bruce H. Vaughn, Bo Møllesøe Vinther, E. Waddington, Anna Wegner, Ilka Weikusat, James W. C. White, Frank Wilhelms, Mai Winstrup, Emmanuel Witrant, Eric W. Wolff, C. Xiao, J. Zheng, N Community 
01 Jan 2013
TL;DR: The new North Greenland Eemian Ice Drilling (‘NEEM’) ice core is presented and shows only a modest ice-sheet response to the strong warming in the early Eemians, which was probably driven by the decreasing summer insolation.
Abstract: Efforts to extract a Greenland ice core with a complete record of the Eemian interglacial (130,000 to 115,000 years ago) have until now been unsuccessful. The response of the Greenland ice sheet to the warmer-than-present climate of the Eemian has thus remained unclear. Here we present the new North Greenland Eemian Ice Drilling ('NEEM') ice core and show only a modest ice-sheet response to the strong warming in the early Eemian. We reconstructed the Eemian record from folded ice using globally homogeneous parameters known from dated Greenland and Antarctic ice-core records. On the basis of water stable isotopes, NEEM surface temperatures after the onset of the Eemian (126,000 years ago) peaked at 8 +/- 4 degrees Celsius above the mean of the past millennium, followed by a gradual cooling that was probably driven by the decreasing summer insolation. Between 128,000 and 122,000 years ago, the thickness of the northwest Greenland ice sheet decreased by 400 +/- 250 metres, reaching surface elevations 122,000 years ago of 130 +/- 300 metres lower than the present. Extensive surface melt occurred at the NEEM site during the Eemian, a phenomenon witnessed when melt layers formed again at NEEM during the exceptional heat of July 2012. With additional warming, surface melt might become more common in the future.

451 citations

Journal ArticleDOI
Christo Buizert1, Betty Adrian2, Jinho Ahn3, Mary R. Albert4, Richard B. Alley5, Daniel Baggenstos6, T. K. Bauska1, R. C. Bay7, Brian B. Bencivengo2, Charles R. Bentley8, Edward J. Brook1, Nathan Chellman9, Gary D. Clow2, Jihong Cole-Dai10, Howard Conway11, Eric D. Cravens, Kurt M. Cuffey7, Nelia W. Dunbar12, J. S. Edwards1, John M. Fegyveresi5, D. G. Ferris10, Joan J. Fitzpatrick2, Tyler J. Fudge11, Chris J. Gibson8, Vasileios Gkinis13, Vasileios Gkinis14, Joshua J. Goetz8, Stephanie Gregory4, Geoffrey M. Hargreaves2, Nels Iverson12, Jay A. Johnson8, Tyler R. Jones13, M. Kalk1, Matthew J. Kippenhan, B. G. Koffman15, Karl J. Kreutz16, Tanner W. Kuhl8, Donald A. Lebar8, James E. Lee1, Shaun A. Marcott8, Shaun A. Marcott1, Bradley R. Markle11, Olivia J. Maselli9, Joseph R. McConnell9, Kenneth C. McGwire9, Logan Mitchell1, Nicolai B. Mortensen8, Peter Neff17, Kunihiko Nishiizumi7, Richard M. Nunn2, Anais Orsi6, Anais Orsi18, Daniel R. Pasteris9, Joel B Pedro14, Joel B Pedro11, Erin C. Pettit19, P. Buford Price7, John C. Priscu20, Rachael H. Rhodes1, Julia Rosen1, Andrew J. Schauer11, Spruce W. Schoenemann11, Paul J. Sendelbach8, Jeffrey P. Severinghaus6, Alexander J. Shturmakov8, Michael Sigl9, Kristina Slawny8, Joseph M. Souney21, Todd Sowers5, M. K. Spencer22, Eric J. Steig11, Kendrick C. Taylor9, Mark S. Twickler21, Bruce H. Vaughn13, Donald E. Voigt5, Edwin D. Waddington11, Kees C. Welten7, Anthony W. Wendricks8, James W. C. White13, Mai Winstrup14, Mai Winstrup11, G. J. Wong4, Thomas E. Woodruff23 
30 Apr 2015-Nature
TL;DR: A north-to-south directionality of the abrupt climatic signal is demonstrated, which is propagated to the Southern Hemisphere high latitudes by oceanic rather than atmospheric processes, which confirms a central role for ocean circulation in the bipolar seesaw.
Abstract: A new ice core from West Antarctica shows that, during the last ice age, abrupt Northern Hemisphere climate variations were followed two centuries later by a response in Antarctica, suggesting an oceanic propagation of the climate signal to the Southern Hemisphere high latitudes.

298 citations

Journal ArticleDOI
14 Aug 2013-Nature
TL;DR: Results from a new, annually resolved ice-core record from West Antarctica suggest a more active role for the Southern Ocean in the onset of deglaciation than is inferred from ice cores in the East Antarctic interior, which are largely isolated from sea-ice changes.
Abstract: An annually resolved ice-core record from West Antarctica indicates that warming driven by local insolation resulting from sea-ice decline began in that region about 2,000 years before warming in East Antarctica, reconciling two alternative explanations for deglacial warming in the Southern Hemisphere.

284 citations

Journal ArticleDOI
TL;DR: In this article, the authors analyse recent atmosphere, surface ocean and sea-ice observations in this region and assess their trends in the context of palaeoclimate records and climate model simulations.
Abstract: Understanding the causes of recent climatic trends and variability in the high-latitude Southern Hemisphere is hampered by a short instrumental record. Here, we analyse recent atmosphere, surface ocean and sea-ice observations in this region and assess their trends in the context of palaeoclimate records and climate model simulations. Over the 36-year satellite era, significant linear trends in annual mean sea-ice extent, surface temperature and sea-level pressure are superimposed on large interannual to decadal variability. Most observed trends, however, are not unusual when compared with Antarctic palaeoclimate records of the past two centuries. With the exception of the positive trend in the Southern Annular Mode, climate model simulations that include anthropogenic forcing are not compatible with the observed trends. This suggests that natural variability overwhelms the forced response in the observations, but the models may not fully represent this natural variability or may overestimate the magnitude of the forced response.

265 citations


Cited by
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Journal ArticleDOI
TL;DR: While the book is a standard fixture in most chemical and physical laboratories, including those in medical centers, it is not as frequently seen in the laboratories of physician's offices (those either in solo or group practice), and I believe that the Handbook can be useful in those laboratories.
Abstract: There is a special reason for reviewing this book at this time: it is the 50th edition of a compendium that is known and used frequently in most chemical and physical laboratories in many parts of the world. Surely, a publication that has been published for 56 years, withstanding the vagaries of science in this century, must have had something to offer. There is another reason: while the book is a standard fixture in most chemical and physical laboratories, including those in medical centers, it is not as frequently seen in the laboratories of physician's offices (those either in solo or group practice). I believe that the Handbook can be useful in those laboratories. One of the reasons, among others, is that the various basic items of information it offers may be helpful in new tests, either physical or chemical, which are continuously being published. The basic information may relate

2,493 citations

Journal ArticleDOI
31 Mar 2016-Nature
TL;DR: A model coupling ice sheet and climate dynamics—including previously underappreciated processes linking atmospheric warming with hydrofracturing of buttressing ice shelves and structural collapse of marine-terminating ice cliffs—is calibrated against Pliocene and Last Interglacial sea-level estimates and applied to future greenhouse gas emission scenarios.
Abstract: Polar temperatures over the last several million years have, at times, been slightly warmer than today, yet global mean sea level has been 6-9 metres higher as recently as the Last Interglacial (130,000 to 115,000 years ago) and possibly higher during the Pliocene epoch (about three million years ago). In both cases the Antarctic ice sheet has been implicated as the primary contributor, hinting at its future vulnerability. Here we use a model coupling ice sheet and climate dynamics-including previously underappreciated processes linking atmospheric warming with hydrofracturing of buttressing ice shelves and structural collapse of marine-terminating ice cliffs-that is calibrated against Pliocene and Last Interglacial sea-level estimates and applied to future greenhouse gas emission scenarios. Antarctica has the potential to contribute more than a metre of sea-level rise by 2100 and more than 15 metres by 2500, if emissions continue unabated. In this case atmospheric warming will soon become the dominant driver of ice loss, but prolonged ocean warming will delay its recovery for thousands of years.

1,433 citations

Journal ArticleDOI
TL;DR: In this paper, a more detailed and extended version of the Greenland Stadials (GS) and Greenland Interstadials (GI) template for the whole of the last glacial period is presented, based on a synchronization of the NGRIP, GRIP, and GISP2 ice-core records.

1,417 citations

Journal ArticleDOI
Marielle Saunois1, Ann R. Stavert2, Ben Poulter3, Philippe Bousquet1, Josep G. Canadell2, Robert B. Jackson4, Peter A. Raymond5, Edward J. Dlugokencky6, Sander Houweling7, Sander Houweling8, Prabir K. Patra9, Prabir K. Patra10, Philippe Ciais1, Vivek K. Arora, David Bastviken11, Peter Bergamaschi, Donald R. Blake12, Gordon Brailsford13, Lori Bruhwiler6, Kimberly M. Carlson14, Mark Carrol3, Simona Castaldi15, Naveen Chandra9, Cyril Crevoisier16, Patrick M. Crill17, Kristofer R. Covey18, Charles L. Curry19, Giuseppe Etiope20, Giuseppe Etiope21, Christian Frankenberg22, Nicola Gedney23, Michaela I. Hegglin24, Lena Höglund-Isaksson25, Gustaf Hugelius17, Misa Ishizawa26, Akihiko Ito26, Greet Janssens-Maenhout, Katherine M. Jensen27, Fortunat Joos28, Thomas Kleinen29, Paul B. Krummel2, Ray L. Langenfelds2, Goulven Gildas Laruelle, Licheng Liu30, Toshinobu Machida26, Shamil Maksyutov26, Kyle C. McDonald27, Joe McNorton31, Paul A. Miller32, Joe R. Melton, Isamu Morino26, Jurek Müller28, Fabiola Murguia-Flores33, Vaishali Naik34, Yosuke Niwa26, Sergio Noce, Simon O'Doherty33, Robert J. Parker35, Changhui Peng36, Shushi Peng37, Glen P. Peters, Catherine Prigent, Ronald G. Prinn38, Michel Ramonet1, Pierre Regnier, William J. Riley39, Judith A. Rosentreter40, Arjo Segers, Isobel J. Simpson12, Hao Shi41, Steven J. Smith42, L. Paul Steele2, Brett F. Thornton17, Hanqin Tian41, Yasunori Tohjima26, Francesco N. Tubiello43, Aki Tsuruta44, Nicolas Viovy1, Apostolos Voulgarakis45, Apostolos Voulgarakis46, Thomas Weber47, Michiel van Weele48, Guido R. van der Werf7, Ray F. Weiss49, Doug Worthy, Debra Wunch50, Yi Yin22, Yi Yin1, Yukio Yoshida26, Weiya Zhang32, Zhen Zhang51, Yuanhong Zhao1, Bo Zheng1, Qing Zhu39, Qiuan Zhu52, Qianlai Zhuang30 
Université Paris-Saclay1, Commonwealth Scientific and Industrial Research Organisation2, Goddard Space Flight Center3, Stanford University4, Yale University5, National Oceanic and Atmospheric Administration6, VU University Amsterdam7, Netherlands Institute for Space Research8, Japan Agency for Marine-Earth Science and Technology9, Chiba University10, Linköping University11, University of California, Irvine12, National Institute of Water and Atmospheric Research13, New York University14, Seconda Università degli Studi di Napoli15, École Polytechnique16, Stockholm University17, Skidmore College18, University of Victoria19, Babeș-Bolyai University20, National Institute of Geophysics and Volcanology21, California Institute of Technology22, Met Office23, University of Reading24, International Institute for Applied Systems Analysis25, National Institute for Environmental Studies26, City University of New York27, University of Bern28, Max Planck Society29, Purdue University30, European Centre for Medium-Range Weather Forecasts31, Lund University32, University of Bristol33, Geophysical Fluid Dynamics Laboratory34, University of Leicester35, Université du Québec à Montréal36, Peking University37, Massachusetts Institute of Technology38, Lawrence Berkeley National Laboratory39, Southern Cross University40, Auburn University41, Joint Global Change Research Institute42, Food and Agriculture Organization43, Finnish Meteorological Institute44, Technical University of Crete45, Imperial College London46, University of Rochester47, Royal Netherlands Meteorological Institute48, Scripps Institution of Oceanography49, University of Toronto50, University of Maryland, College Park51, Hohai University52
TL;DR: The second version of the living review paper dedicated to the decadal methane budget, integrating results of top-down studies (atmospheric observations within an atmospheric inverse-modeling framework) and bottom-up estimates (including process-based models for estimating land surface emissions and atmospheric chemistry, inventories of anthropogenic emissions, and data-driven extrapolations) as discussed by the authors.
Abstract: Understanding and quantifying the global methane (CH4) budget is important for assessing realistic pathways to mitigate climate change. Atmospheric emissions and concentrations of CH4 continue to increase, making CH4 the second most important human-influenced greenhouse gas in terms of climate forcing, after carbon dioxide (CO2). The relative importance of CH4 compared to CO2 depends on its shorter atmospheric lifetime, stronger warming potential, and variations in atmospheric growth rate over the past decade, the causes of which are still debated. Two major challenges in reducing uncertainties in the atmospheric growth rate arise from the variety of geographically overlapping CH4 sources and from the destruction of CH4 by short-lived hydroxyl radicals (OH). To address these challenges, we have established a consortium of multidisciplinary scientists under the umbrella of the Global Carbon Project to synthesize and stimulate new research aimed at improving and regularly updating the global methane budget. Following Saunois et al. (2016), we present here the second version of the living review paper dedicated to the decadal methane budget, integrating results of top-down studies (atmospheric observations within an atmospheric inverse-modelling framework) and bottom-up estimates (including process-based models for estimating land surface emissions and atmospheric chemistry, inventories of anthropogenic emissions, and data-driven extrapolations). For the 2008–2017 decade, global methane emissions are estimated by atmospheric inversions (a top-down approach) to be 576 Tg CH4 yr−1 (range 550–594, corresponding to the minimum and maximum estimates of the model ensemble). Of this total, 359 Tg CH4 yr−1 or ∼ 60 % is attributed to anthropogenic sources, that is emissions caused by direct human activity (i.e. anthropogenic emissions; range 336–376 Tg CH4 yr−1 or 50 %–65 %). The mean annual total emission for the new decade (2008–2017) is 29 Tg CH4 yr−1 larger than our estimate for the previous decade (2000–2009), and 24 Tg CH4 yr−1 larger than the one reported in the previous budget for 2003–2012 (Saunois et al., 2016). Since 2012, global CH4 emissions have been tracking the warmest scenarios assessed by the Intergovernmental Panel on Climate Change. Bottom-up methods suggest almost 30 % larger global emissions (737 Tg CH4 yr−1, range 594–881) than top-down inversion methods. Indeed, bottom-up estimates for natural sources such as natural wetlands, other inland water systems, and geological sources are higher than top-down estimates. The atmospheric constraints on the top-down budget suggest that at least some of these bottom-up emissions are overestimated. The latitudinal distribution of atmospheric observation-based emissions indicates a predominance of tropical emissions (∼ 65 % of the global budget, < 30∘ N) compared to mid-latitudes (∼ 30 %, 30–60∘ N) and high northern latitudes (∼ 4 %, 60–90∘ N). The most important source of uncertainty in the methane budget is attributable to natural emissions, especially those from wetlands and other inland waters. Some of our global source estimates are smaller than those in previously published budgets (Saunois et al., 2016; Kirschke et al., 2013). In particular wetland emissions are about 35 Tg CH4 yr−1 lower due to improved partition wetlands and other inland waters. Emissions from geological sources and wild animals are also found to be smaller by 7 Tg CH4 yr−1 by 8 Tg CH4 yr−1, respectively. However, the overall discrepancy between bottom-up and top-down estimates has been reduced by only 5 % compared to Saunois et al. (2016), due to a higher estimate of emissions from inland waters, highlighting the need for more detailed research on emissions factors. Priorities for improving the methane budget include (i) a global, high-resolution map of water-saturated soils and inundated areas emitting methane based on a robust classification of different types of emitting habitats; (ii) further development of process-based models for inland-water emissions; (iii) intensification of methane observations at local scales (e.g., FLUXNET-CH4 measurements) and urban-scale monitoring to constrain bottom-up land surface models, and at regional scales (surface networks and satellites) to constrain atmospheric inversions; (iv) improvements of transport models and the representation of photochemical sinks in top-down inversions; and (v) development of a 3D variational inversion system using isotopic and/or co-emitted species such as ethane to improve source partitioning.

1,047 citations

Journal ArticleDOI
30 Jun 2016-Nature
TL;DR: Observations indicate that insolation, in part, sets the pace of the occurrence of millennial-scale events, including those associated with terminations and ‘unfinished terminations’.
Abstract: Oxygen isotope records from Chinese caves characterize changes in both the Asian monsoon and global climate. Here, using our new speleothem data, we extend the Chinese record to cover the full uranium/thorium dating range, that is, the past 640,000 years. The record’s length and temporal precision allow us to test the idea that insolation changes caused by the Earth’s precession drove the terminations of each of the last seven ice ages as well as the millennia-long intervals of reduced monsoon rainfall associated with each of the terminations. On the basis of our record’s timing, the terminations are separated by four or five precession cycles, supporting the idea that the ‘100,000-year’ ice age cycle is an average of discrete numbers of precession cycles. Furthermore, the suborbital component of monsoon rainfall variability exhibits power in both the precession and obliquity bands, and is nearly in anti-phase with summer boreal insolation. These observations indicate that insolation, in part, sets the pace of the occurrence of millennial-scale events, including those associated with terminations and ‘unfinished terminations’. Records of the Asian monsoon have been extended to 640,000 years ago, and confirm both that the 100,000-year ice age cycle results from integral numbers of precessional cycles and that insolation influences the pacing of major millennial-scale climate events. Prior records of the Asian monsoon have revealed cyclic variations over hundreds of thousands of years, probably driven by variations in insolation caused by the precession of Earth's orbit. Hai Cheng and colleagues now provide a speleothem record from Chinese cave samples that extends earlier records to 640,000 years ago, close to the maximum age possible with uranium/thorium dating. This spectacular record confirms that the characteristic '100,000-year' ice age cycle corresponds to an integral number (four or five) of precession cycles, and that insolation influences millennial-scale variations in monsoon strength.

879 citations