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Climate change
About: Climate change is a research topic. Over the lifetime, 99222 publications have been published within this topic receiving 3572006 citations.
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TL;DR: It is shown that the carbon–climate response (CCR), defined as the ratio of temperature change to cumulative carbon emissions, is approximately independent of both the atmospheric CO2 concentration and its rate of change on these timescales.
Abstract: Climate sensitivity models may inaccurately characterize the full Earth system response, as they ignore changes in the carbon cycle, aerosols, land use and land cover. A combination of a simplified climate model, a range of simulations from a recent model intercomparison and historical constraints now show that, independent of the timing of emissions or the atmospheric concentration of CO2, emitting a trillion tonnes of carbon will cause global warming of 1.0 to 2.1 degrees Celsius.
841 citations
TL;DR: It is suggested that changes in the strength of tropical methane sources and sinks (wetlands, atmospheric oxidation) controlled the atmospheric methane budget, with an additional source input during major terminations as the retreat of the northern ice sheet allowed higher methane emissions from extending periglacial wetlands.
Abstract: Atmospheric methane is an important greenhouse gas and a sensitive indicator of climate change and millennial-scale temperature variability. Its concentrations over the past 650,000 years have varied between 350 and 800 parts per 109 by volume (p.p.b.v.) during glacial and interglacial periods, respectively. In comparison, present-day methane levels of 1,770 p.p.b.v. have been reported. Insights into the external forcing factors and internal feedbacks controlling atmospheric methane are essential for predicting the methane budget in a warmer world. Here we present a detailed atmospheric methane record from the EPICA Dome C ice core that extends the history of this greenhouse gas to 800,000 yr before present. The average time resolution of the new data is 380 yr and permits the identification of orbital and millennial-scale features. Spectral analyses indicate that the long-term variability in atmospheric methane levels is dominated by 100,000 yr glacial–interglacial cycles up to 400,000 yr ago with an increasing contribution of the precessional component during the four more recent climatic cycles. We suggest that changes in the strength of tropical methane sources and sinks (wetlands, atmospheric oxidation), possibly influenced by changes in monsoon systems and the position of the intertropical convergence zone, controlled the atmospheric methane budget, with an additional source input during major terminations as the retreat of the northern ice sheet allowed higher methane emissions from extending periglacial wetlands. Millennial-scale changes in methane levels identified in our record as being associated with Antarctic isotope maxima events are indicative of ubiquitous millennial-scale temperature variability during the past eight glacial cycles.
839 citations
TL;DR: The recent past may be insufficient for prediction, however, as feedbacks between the carbon cycle and climate become more prominent as mentioned in this paper, leading to more accurate predictions of future concentrations of CO2 and more accurate prediction of the rate and extent of climate change.
Abstract: The global carbon budget is, of course, balanced. The conservation of carbon and the first law of thermodynamics are intact. “Balancing the carbon budget” refers to the state of the science in evaluating the terms of the global carbon equation. The annual increases in the amount of carbon in the atmosphere, oceans, and land should balance the emissions of carbon from fossil fuels and deforestation. Balancing the carbon budget is not the real issue, however. The real issue is understanding the processes responsible for net sources and sinks of carbon. Such understanding should lead to more accurate predictions of future concentrations of CO2 and more accurate predictions of the rate and extent of climatic change. The recent past may be insufficient for prediction, however. Oceanic and terrestrial sinks that have lessened the rate of growth in atmospheric CO2 until now may diminish as feedbacks between the carbon cycle and climate become more prominent.
839 citations
Northern Arizona University1, United States Geological Survey2, Loughborough University3, University of Washington4, University of Colorado Boulder5, University of Oregon6, University of New Brunswick7, Bates College8, Geological Survey of Canada9, Norwegian University of Science and Technology10, University of Cincinnati11, University of Ottawa12, University of Iceland13, University of Illinois at Urbana–Champaign14, University of Edinburgh15, University of Denver16, University of California, Los Angeles17, University of South Carolina18, National Center for Atmospheric Research19, California State University, Long Beach20, Queen's University21, Wilfrid Laurier University22
TL;DR: In this paper, a spatio-temporal pattern of peak Holocene warmth (Holocene thermal maximum, HTM) is traced over 140 sites across the Western Hemisphere of the Arctic (0−180°W; north of ∼60°N).
838 citations
Lamont–Doherty Earth Observatory1, University of Bristol2, Wesleyan University3, Yale University4, National Oceanography Centre, Southampton5, Utrecht University6, University of Hawaii at Manoa7, Pennsylvania State University8, University of Southern California9, Museum für Naturkunde10, University of North Carolina at Chapel Hill11, University of California, Santa Cruz12, Cardiff University13, Institute of Arctic and Alpine Research14, University of South Florida St. Petersburg15, VU University Amsterdam16, Autonomous University of Barcelona17, Claremont McKenna College18
TL;DR: This paper reviewed events exhibiting evidence for elevated atmospheric CO2, global warming, and ocean acidification over the past ~300 million years of Earth's history, some with contemporaneous extinction or evolutionary turnover among marine calcifiers.
Abstract: Ocean acidification may have severe consequences for marine ecosystems; however, assessing its future impact is difficult because laboratory experiments and field observations are limited by their reduced ecologic complexity and sample period, respectively. In contrast, the geological record contains long-term evidence for a variety of global environmental perturbations, including ocean acidification plus their associated biotic responses. We review events exhibiting evidence for elevated atmospheric CO2, global warming, and ocean acidification over the past ~300 million years of Earth’s history, some with contemporaneous extinction or evolutionary turnover among marine calcifiers. Although similarities exist, no past event perfectly parallels future projections in terms of disrupting the balance of ocean carbonate chemistry—a consequence of the unprecedented rapidity of CO2 release currently taking place.
838 citations