Author
Peter D. Ditlevsen
Other affiliations: National Center for Atmospheric Research, Technical University of Denmark, Niels Bohr Institute ...read more
Bio: Peter D. Ditlevsen is an academic researcher from University of Copenhagen. The author has contributed to research in topics: Glacial period & Ice core. The author has an hindex of 28, co-authored 106 publications receiving 3333 citations. Previous affiliations of Peter D. Ditlevsen include National Center for Atmospheric Research & Technical University of Denmark.
Topics: Glacial period, Ice core, Turbulence, Climate change, Ice age
Papers published on a yearly basis
Papers
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Dartmouth College1, Uppsala University2, Nagaoka University of Technology3, University of Copenhagen4, Heidelberg University5, Natural Resources Canada6, Oregon State University7, Centre national de la recherche scientifique8, Korean Ocean Research and Development Institute9, Swansea University10, University of Bern11, British Antarctic Survey12, University of Kansas13, National Institute of Polar Research14, University of Iceland15, Stockholm University16, Vrije Universiteit Brussel17, University of Colorado Boulder18, Alfred Wegener Institute for Polar and Marine Research19, University of Washington20, Arctic and Antarctic Research Institute21, Desert Research Institute22, Hokkaido University23, University of Grenoble24, University of California, San Diego25, Université libre de Bruxelles26, Utrecht University27, Oeschger Centre for Climate Change Research28, Max Planck Society29, Swiss Federal Institute for Forest, Snow and Landscape Research30, ETH Zurich31, United Arab Emirates University32, Paul Scherrer Institute33, École Polytechnique Fédérale de Lausanne34, University of East Anglia35, Geological Survey of Canada36
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
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
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TL;DR: In this article, it was shown that the fast time scale noise forcing the climate contains a component with an -stable distribution, and that abrupt climatic changes observed could be triggered by single extreme events.
Abstract: The last glacial period showed millennium scale climatic shifts between two dieren t stable climate states. The state of thermohaline ocean circulation probably gov- erns the climate, and the triggering mechanism for climate changes is random uctuation s of the atmospheric forcing on the ocean circulation. The high temporal resolution paleo- climatic data from ice-cores are consistent with this picture and a bi-stable climate pseudo-potential can be derived. It is found that the fast time scale noise forcing the climate contains a component with an -stable distribution. As a consequence the abrupt climatic changes observed could be triggered by single extreme events. These events are re- lated to ocean-atmosphere dynamics on annual or shorter time scales and could indicate a fundamental limitation in predictability of climate changes. Paleoclimatic records from ice-cores (Dansgaard et al.,
322 citations
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TL;DR: In this article, a high-resolution ice core record was used to identify the most pronounced changes observed, beside the glacial terminations, are the Dansgaard-Oeschger events, which strongly suggest that they are noise induced and thus have very limited predictability.
Abstract: [1] The causes for and possible predictions of rapid climate changes are poorly understood. The most pronounced changes observed, beside the glacial terminations, are the Dansgaard-Oeschger events. Present day general circulation climate models simulating glacial conditions are not capable of reproducing these rapid shifts. It is thus not known if they are due to bifurcations in the structural stability of the climate or if they are induced by stochastic fluctuations. By analyzing a high resolution ice core record we exclude the bifurcation scenario, which strongly suggests that they are noise induced and thus have very limited predictability.
213 citations
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TL;DR: Noise-induced jumping between metastable states in a potential depends on the structure of the noise, and jumping triggered by single extreme events contributes to the transition probability for an alpha-stable noise.
Abstract: Noise-induced jumping between metastable states in a potential depends on the structure of the noise. For an $\ensuremath{\alpha}$-stable noise, jumping triggered by single extreme events contributes to the transition probability. This is also called Levy flights and might be of importance in triggering sudden changes in geophysical flow and perhaps even climatic changes. The steady-state statistics is also influenced by the noise structure leading to a non-Gibbs distribution for an $\ensuremath{\alpha}$-stable noise.
156 citations
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2,345 citations
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TL;DR: How previously isolated lines of work can be connected are reviewed, it is concluded that many critical transitions (such as escape from the poverty trap) can have positive outcomes, and how the new approaches to sensing fragility can help to detect both risks and opportunities for desired change.
Abstract: Tipping points in complex systems may imply risks of unwanted collapse, but also opportunities for positive change. Our capacity to navigate such risks and opportunities can be boosted by combining emerging insights from two unconnected fields of research. One line of work is revealing fundamental architectural features that may cause ecological networks, financial markets, and other complex systems to have tipping points. Another field of research is uncovering generic empirical indicators of the proximity to such critical thresholds. Although sudden shifts in complex systems will inevitably continue to surprise us, work at the crossroads of these emerging fields offers new approaches for anticipating critical transitions.
1,617 citations
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TL;DR: A copy of the Guangbo jiemu bao [Broadcast Program Report] was being passed from hand to hand among a group of young people eager to be the first to read the article introducing the program "What Is Revolutionary Love?".
Abstract: A copy of Guangbo jiemu bao [Broadcast Program Report] was being passed from hand to hand among a group of young people eager to be the first to read the article introducing the program "What Is Revolutionary Love?" It said: "… Young friends, you are certainly very concerned about this problem'. So, we would like you to meet the young women workers Meng Xiaoyu and Meng Yamei and the older cadre Miss Feng. They are the three leading characters in the short story ‘The Place of Love.’ Through the description of the love lives of these three, the story induces us to think deeply about two questions that merit further examination.
1,528 citations
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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
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University of Copenhagen1, University of Bern2, Royal Holloway, University of London3, Carnegie Institution for Science4, Centre national de la recherche scientifique5, Utrecht University6, Joint Institute for the Study of the Atmosphere and Ocean7, University of Wales, Lampeter8, Aberystwyth University9, University of Sheffield10, University of Washington11
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