Author
Kevin Schaefer
Other affiliations: Institute of Arctic and Alpine Research, University of Colorado Boulder
Bio: Kevin Schaefer is an academic researcher from Cooperative Institute for Research in Environmental Sciences. The author has contributed to research in topics: Permafrost & Climate change. The author has an hindex of 48, co-authored 123 publications receiving 10813 citations. Previous affiliations of Kevin Schaefer include Institute of Arctic and Alpine Research & University of Colorado Boulder.
Topics: Permafrost, Climate change, Soil carbon, Biosphere, Global warming
Papers published on a yearly basis
Papers
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Northern Arizona University1, University of Alaska Fairbanks2, University of Florida3, Alfred Wegener Institute for Polar and Marine Research4, United States Geological Survey5, Oak Ridge National Laboratory6, Stockholm University7, Lawrence Berkeley National Laboratory8, National Center for Atmospheric Research9, Woods Hole Research Center10, University of Alberta11, Tyumen State Oil and Gas University12, University of Guelph13, University of New Hampshire14, Utrecht University15
TL;DR: In this paper, the authors find that current evidence suggests a gradual and prolonged release of greenhouse gas emissions in a warming climate and present a research strategy with which to target poorly understood aspects of permafrost carbon dynamics.
Abstract: Large quantities of organic carbon are stored in frozen soils (permafrost) within Arctic and sub-Arctic regions. A warming climate can induce environmental changes that accelerate the microbial breakdown of organic carbon and the release of the greenhouse gases carbon dioxide and methane. This feedback can accelerate climate change, but the magnitude and timing of greenhouse gas emission from these regions and their impact on climate change remain uncertain. Here we find that current evidence suggests a gradual and prolonged release of greenhouse gas emissions in a warming climate and present a research strategy with which to target poorly understood aspects of permafrost carbon dynamics.
2,282 citations
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TL;DR: In this paper, the authors explored nonlinear transitions in the Arctic feedbacks and their subsequent impacts on the global climate and economy under the Paris Agreement scenarios, and found an important contribution to warming which leads to additional economic losses from climate change.
Abstract: Arctic feedbacks accelerate climate change through carbon releases from thawing permafrost and higher solar absorption from reductions in the surface albedo, following loss of sea ice and land snow. Here, we include dynamic emulators of complex physical models in the integrated assessment model PAGE-ICE to explore nonlinear transitions in the Arctic feedbacks and their subsequent impacts on the global climate and economy under the Paris Agreement scenarios. The permafrost feedback is increasingly positive in warmer climates, while the albedo feedback weakens as the ice and snow melt. Combined, these two factors lead to significant increases in the mean discounted economic effect of climate change: +4.0% ($24.8 trillion) under the 1.5 °C scenario, +5.5% ($33.8 trillion) under the 2 °C scenario, and +4.8% ($66.9 trillion) under mitigation levels consistent with the current national pledges. Considering the nonlinear Arctic feedbacks makes the 1.5 °C target marginally more economically attractive than the 2 °C target, although both are statistically equivalent. Nonlinear transitions in permafrost carbon feedback and surface albedo feedback have largely been excluded from climate policy studies. Here the authors modelled the dynamics of the two nonlinear feedbacks and the associated uncertainty, and found an important contribution to warming which leads to additional economic losses from climate change.
782 citations
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Harvard University1, University of Montana2, McMaster University3, Environment Canada4, Ohio State University5, Auburn University6, University of Toronto7, Centre national de la recherche scientifique8, Pennsylvania State University9, University of Wisconsin-Madison10, University of Illinois at Urbana–Champaign11, Indiana University12, Virginia Commonwealth University13, University of Alberta14, United States Forest Service15, Laval University16, Queen's University17, Cooperative Institute for Research in Environmental Sciences18, Oak Ridge National Laboratory19, Princeton University20, University of Colorado Boulder21, Ensenada Center for Scientific Research and Higher Education22, Ghent University23, University of New Hampshire24, University of California, Los Angeles25
TL;DR: In this article, the authors evaluate the representation of phenology, and the associated seasonality of ecosystem-scale CO2 exchange, in 14 models participating in the North American Carbon Program Site Synthesis.
Abstract: Phenology, by controlling the seasonal activity of vegetation on the land surface, plays a fundamental role in regulating photosynthesis and other ecosystem processes, as well as competitive interactions and feedbacks to the climate system. We conducted an analysis to evaluate the representation of phenology, and the associated seasonality of ecosystem-scale CO2 exchange, in 14 models participating in the North American Carbon Program Site Synthesis. Model predictions were evaluated using long-term measurements (emphasizing the period 2000–2006) from 10 forested sites within the AmeriFlux and Fluxnet-Canada networks. In deciduous forests, almost all models consistently predicted that the growing season started earlier, and ended later, than was actually observed; biases of 2 weeks or more were
578 citations
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Woods Hole Research Center1, Northern Arizona University2, University of Utah3, Carnegie Institution for Science4, California Institute of Technology5, University of Nevada, Reno6, University of New Mexico7, United States Forest Service8, Princeton University9, Oak Ridge National Laboratory10, University of Maine11, Pacific Northwest National Laboratory12, University of Illinois at Urbana–Champaign13, Auburn University14
TL;DR: This analysis of three independent datasets of gross primary productivity shows that, across diverse ecosystems, drought recovery times are strongly associated with climate and carbon cycle dynamics, with biodiversity and CO2 fertilization as secondary factors.
Abstract: Drought, a recurring phenomenon with major impacts on both human and natural systems, is the most widespread climatic extreme that negatively affects the land carbon sink. Although twentieth-century trends in drought regimes are ambiguous, across many regions more frequent and severe droughts are expected in the twenty-first century. Recovery time-how long an ecosystem requires to revert to its pre-drought functional state-is a critical metric of drought impact. Yet the factors influencing drought recovery and its spatiotemporal patterns at the global scale are largely unknown. Here we analyse three independent datasets of gross primary productivity and show that, across diverse ecosystems, drought recovery times are strongly associated with climate and carbon cycle dynamics, with biodiversity and CO2 fertilization as secondary factors. Our analysis also provides two key insights into the spatiotemporal patterns of drought recovery time: first, that recovery is longest in the tropics and high northern latitudes (both vulnerable areas of Earth's climate system) and second, that drought impacts (assessed using the area of ecosystems actively recovering and time to recovery) have increased over the twentieth century. If droughts become more frequent, as expected, the time between droughts may become shorter than drought recovery time, leading to permanently damaged ecosystems and widespread degradation of the land carbon sink.
492 citations
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TL;DR: In this article, the authors use surface weather from three global climate models based on the moderate warming, A1B Intergovernmental Panel on Climate Change emissions scenario and the SiBCASA land surface model to estimate the strength and timing of the positive permafrost carbon feedback (PCF) and associated uncertainty.
Abstract: The thaw and release of carbon currently frozen in permafrost will increase atmospheric CO 2 concentrations and amplify surface warming to initiate a positive permafrost carbon feedback (PCF) on climate. We use surface weather from three global climate models based on the moderate warming, A1B Intergovernmental Panel on Climate Change emissions scenario and the SiBCASA land surface model to estimate the strength and timing of the PCF and associated uncertainty. By 2200, we predict a 29–59% decrease in permafrost area and a 53–97 cm increase in active layer thickness. By 2200, the PCF strength in terms of cumulative permafrost carbon flux to the atmosphere is 190 ± 64 Gt C. This estimate may be low because it does not account for amplified surface warming due to the PCF itself and excludes some discontinuous permafrost regions where SiBCASA did not simulate permafrost. We predict that the PCF will change the arctic from a carbon sink to a source after the mid-2020s and is strong enough to cancel 42–88% of the total global land sink. The thaw and decay of permafrost carbon is irreversible and accounting for the PCF will require larger reductions in fossil fuel emissions to reach a target atmospheric CO 2 concentration. DOI: 10.1111/j.1600-0889.2011.00527.x
378 citations
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01 Jan 2016
TL;DR: The modern applied statistics with s is universally compatible with any devices to read, and is available in the digital library an online access to it is set as public so you can download it instantly.
Abstract: Thank you very much for downloading modern applied statistics with s. As you may know, people have search hundreds times for their favorite readings like this modern applied statistics with s, but end up in harmful downloads. Rather than reading a good book with a cup of coffee in the afternoon, instead they cope with some harmful virus inside their laptop. modern applied statistics with s is available in our digital library an online access to it is set as public so you can download it instantly. Our digital library saves in multiple countries, allowing you to get the most less latency time to download any of our books like this one. Kindly say, the modern applied statistics with s is universally compatible with any devices to read.
5,249 citations
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TL;DR: In this article, the authors present a document, redatto, voted and pubblicato by the Ipcc -Comitato intergovernativo sui cambiamenti climatici - illustra la sintesi delle ricerche svolte su questo tema rilevante.
Abstract: Cause, conseguenze e strategie di mitigazione Proponiamo il primo di una serie di articoli in cui affronteremo l’attuale problema dei mutamenti climatici. Presentiamo il documento redatto, votato e pubblicato dall’Ipcc - Comitato intergovernativo sui cambiamenti climatici - che illustra la sintesi delle ricerche svolte su questo tema rilevante.
4,187 citations
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TL;DR: In this paper, the authors provide a synthesis of past research on the role of soil moisture for the climate system, based both on modelling and observational studies, focusing on soil moisture-temperature and soil moistureprecipitation feedbacks, and their possible modifications with climate change.
3,402 citations
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Northern Arizona University1, University of Alaska Fairbanks2, University of Florida3, Alfred Wegener Institute for Polar and Marine Research4, United States Geological Survey5, Oak Ridge National Laboratory6, Stockholm University7, Lawrence Berkeley National Laboratory8, National Center for Atmospheric Research9, Woods Hole Research Center10, University of Alberta11, Tyumen State Oil and Gas University12, University of Guelph13, University of New Hampshire14, Utrecht University15
TL;DR: In this paper, the authors find that current evidence suggests a gradual and prolonged release of greenhouse gas emissions in a warming climate and present a research strategy with which to target poorly understood aspects of permafrost carbon dynamics.
Abstract: Large quantities of organic carbon are stored in frozen soils (permafrost) within Arctic and sub-Arctic regions. A warming climate can induce environmental changes that accelerate the microbial breakdown of organic carbon and the release of the greenhouse gases carbon dioxide and methane. This feedback can accelerate climate change, but the magnitude and timing of greenhouse gas emission from these regions and their impact on climate change remain uncertain. Here we find that current evidence suggests a gradual and prolonged release of greenhouse gas emissions in a warming climate and present a research strategy with which to target poorly understood aspects of permafrost carbon dynamics.
2,282 citations
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01 Jan 2013
TL;DR: The authors assesses long-term projections of climate change for the end of the 21st century and beyond, where the forced signal depends on the scenario and is typically larger than the internal variability of the climate system.
Abstract: This chapter assesses long-term projections of climate change for the end of the 21st century and beyond, where the forced signal depends on the scenario and is typically larger than the internal variability of the climate system. Changes are expressed with respect to a baseline period of 1986-2005, unless otherwise stated.
2,253 citations