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Stefan Rahmstorf - One of the best experts on this subject based on the ideXlab platform.
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Change points of Global Temperature
Environmental Research Letters, 2015Co-Authors: Niamh Cahill, Stefan Rahmstorf, Andrew C. ParnellAbstract:We aim to address the question of whether or not there is a significant recent 'hiatus', 'pause' or 'slowdown' of Global Temperature rise. Using a statistical technique known as change point (CP) analysis we identify the changes in four Global Temperature records and estimate the rates of Temperature rise before and after these changes occur. For each record the results indicate that three CPs are enough to accurately capture the variability in the data with no evidence of any detectable change in the Global warming trend since ~1970. We conclude that the term 'hiatus' or 'pause' cannot be statistically justified.
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Global Temperature evolution 1979–2010
Environmental Research Letters, 2011Co-Authors: Grant Foster, Stefan RahmstorfAbstract:We analyze five prominent time series of Global Temperature (over land and ocean) for their common time interval since 1979: three surface Temperature records (from NASA/GISS, NOAA/NCDC and HadCRU) and two lower-troposphere (LT) Temperature records based on satellite microwave sensors (from RSS and UAH). All five series show consistent Global warming trends ranging from 0.014 to 0.018 K yr 1 . When the data are adjusted to remove the estimated impact of known factors on short-term Temperature variations (El Ni˜ no/southern oscillation, volcanic aerosols and solar variability), the Global warming signal becomes even more evident as noise is reduced. Lower-troposphere Temperature responds more strongly to El Ni˜ no/southern oscillation and to volcanic forcing than surface Temperature data. The adjusted data show warming at very similar rates to the unadjusted data, with smaller probable errors, and the warming rate is steady over the whole time interval. In all adjusted series, the two hottest years are 2009 and 2010.
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Global Temperature evolution 1979 2010
Environmental Research Letters, 2011Co-Authors: Grant Foster, Stefan RahmstorfAbstract:We analyze five prominent time series of Global Temperature (over land and ocean) for their common time interval since 1979: three surface Temperature records (from NASA/GISS, NOAA/NCDC and HadCRU) and two lower-troposphere (LT) Temperature records based on satellite microwave sensors (from RSS and UAH). All five series show consistent Global warming trends ranging from 0.014 to 0.018 K yr 1 . When the data are adjusted to remove the estimated impact of known factors on short-term Temperature variations (El Ni˜ no/southern oscillation, volcanic aerosols and solar variability), the Global warming signal becomes even more evident as noise is reduced. Lower-troposphere Temperature responds more strongly to El Ni˜ no/southern oscillation and to volcanic forcing than surface Temperature data. The adjusted data show warming at very similar rates to the unadjusted data, with smaller probable errors, and the warming rate is steady over the whole time interval. In all adjusted series, the two hottest years are 2009 and 2010.
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Global sea level linked to Global Temperature
Proceedings of the National Academy of Sciences of the United States of America, 2009Co-Authors: Martin Vermeer, Stefan RahmstorfAbstract:We propose a simple relationship linking Global sea-level variations on time scales of decades to centuries to Global mean Temperature. This relationship is tested on synthetic data from a Global climate model for the past millennium and the next century. When applied to observed data of sea level and Temperature for 1880–2000, and taking into account known anthropogenic hydrologic contributions to sea level, the correlation is >0.99, explaining 98% of the variance. For future Global Temperature scenarios of the Intergovernmental Panel on Climate Change's Fourth Assessment Report, the relationship projects a sea-level rise ranging from 75 to 190 cm for the period 1990–2100.
Carolyn W. Snyder - One of the best experts on this subject based on the ideXlab platform.
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Evolution of Global Temperature over the past two million years
Nature, 2016Co-Authors: Carolyn W. SnyderAbstract:Reconstruction of Global average surface Temperature for the past two million years shows continuous cooling until about 1.2 million years ago, followed by a general flattening, with close coupling of Global Temperature and atmospheric greenhouse gas concentrations over the past 800,000 years. Although there are many geochemical records of past climate variability, an extensive reconstruction of Global average surface Temperature (GAST) has so far been lacking. Carolyn Snyder has used a network of sea surface Temperature reconstructions to reconstruct the GAST for the past 2 million years. The results show continuous cooling until about 1.2 million years ago, followed by a general flattening of the GAST profile, with close coupling of Global Temperature and atmospheric greenhouse gases over the past 800,000 years. The reconstruction, combined with records of atmospheric CO_2, suggest a future warming of 3–7 degrees Celsius, even if atmospheric CO_2 concentrations stabilize at present-day levels. Reconstructions of Earth’s past climate strongly influence our understanding of the dynamics and sensitivity of the climate system. Yet Global Temperature has been reconstructed for only a few isolated windows of time^ 1 , 2 , and continuous reconstructions across glacial cycles remain elusive. Here I present a spatially weighted proxy reconstruction of Global Temperature over the past 2 million years estimated from a multi-proxy database of over 20,000 sea surface Temperature point reconstructions. Global Temperature gradually cooled until roughly 1.2 million years ago and cooling then stalled until the present. The cooling trend probably stalled before the beginning of the mid-Pleistocene transition^ 3 , and pre-dated the increase in the maximum size of ice sheets around 0.9 million years ago^ 4 , 5 , 6 . Thus, Global cooling may have been a pre-condition for, but probably is not the sole causal mechanism of, the shift to quasi-100,000-year glacial cycles at the mid-Pleistocene transition. Over the past 800,000 years, polar amplification (the amplification of Temperature change at the poles relative to Global Temperature change) has been stable over time, and Global Temperature and atmospheric greenhouse gas concentrations have been closely coupled across glacial cycles. A comparison of the new Temperature reconstruction with radiative forcing from greenhouse gases estimates an Earth system sensitivity of 9 degrees Celsius (range 7 to 13 degrees Celsius, 95 per cent credible interval) change in Global average surface Temperature per doubling of atmospheric carbon dioxide over millennium timescales. This result suggests that stabilization at today’s greenhouse gas levels may already commit Earth to an eventual total warming of 5 degrees Celsius (range 3 to 7 degrees Celsius, 95 per cent credible interval) over the next few millennia as ice sheets, vegetation and atmospheric dust continue to respond to Global warming.
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Evolution of Global Temperature over the past two million years
Nature, 2016Co-Authors: Carolyn W. SnyderAbstract:Reconstruction of Global average surface Temperature for the past two million years shows continuous cooling until about 1.2 million years ago, followed by a general flattening, with close coupling of Global Temperature and atmospheric greenhouse gas concentrations over the past 800,000 years.
Grant Foster - One of the best experts on this subject based on the ideXlab platform.
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Global Temperature evolution 1979–2010
Environmental Research Letters, 2011Co-Authors: Grant Foster, Stefan RahmstorfAbstract:We analyze five prominent time series of Global Temperature (over land and ocean) for their common time interval since 1979: three surface Temperature records (from NASA/GISS, NOAA/NCDC and HadCRU) and two lower-troposphere (LT) Temperature records based on satellite microwave sensors (from RSS and UAH). All five series show consistent Global warming trends ranging from 0.014 to 0.018 K yr 1 . When the data are adjusted to remove the estimated impact of known factors on short-term Temperature variations (El Ni˜ no/southern oscillation, volcanic aerosols and solar variability), the Global warming signal becomes even more evident as noise is reduced. Lower-troposphere Temperature responds more strongly to El Ni˜ no/southern oscillation and to volcanic forcing than surface Temperature data. The adjusted data show warming at very similar rates to the unadjusted data, with smaller probable errors, and the warming rate is steady over the whole time interval. In all adjusted series, the two hottest years are 2009 and 2010.
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Global Temperature evolution 1979 2010
Environmental Research Letters, 2011Co-Authors: Grant Foster, Stefan RahmstorfAbstract:We analyze five prominent time series of Global Temperature (over land and ocean) for their common time interval since 1979: three surface Temperature records (from NASA/GISS, NOAA/NCDC and HadCRU) and two lower-troposphere (LT) Temperature records based on satellite microwave sensors (from RSS and UAH). All five series show consistent Global warming trends ranging from 0.014 to 0.018 K yr 1 . When the data are adjusted to remove the estimated impact of known factors on short-term Temperature variations (El Ni˜ no/southern oscillation, volcanic aerosols and solar variability), the Global warming signal becomes even more evident as noise is reduced. Lower-troposphere Temperature responds more strongly to El Ni˜ no/southern oscillation and to volcanic forcing than surface Temperature data. The adjusted data show warming at very similar rates to the unadjusted data, with smaller probable errors, and the warming rate is steady over the whole time interval. In all adjusted series, the two hottest years are 2009 and 2010.
Anastasios A. Tsonis - One of the best experts on this subject based on the ideXlab platform.
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dynamical evidence for causality between galactic cosmic rays and interannual variation in Global Temperature
Proceedings of the National Academy of Sciences of the United States of America, 2015Co-Authors: Anastasios A. Tsonis, Kyle L. Swanson, Ethan R Deyle, Robert M May, George Sugihara, Joshua D Verbeten, Geli WangAbstract:As early as 1959, it was hypothesized that an indirect link between solar activity and climate could be mediated by mechanisms controlling the flux of galactic cosmic rays (CR) [Ney ER (1959) Nature 183:451-452]. Although the connection between CR and climate remains controversial, a significant body of laboratory evidence has emerged at the European Organization for Nuclear Research [Duplissy J, et al. (2010) Atmos Chem Phys 10:1635-1647; Kirkby J, et al. (2011) Nature 476(7361):429-433] and elsewhere [Svensmark H, Pedersen JOP, Marsh ND, Enghoff MB, Uggerhoj UI (2007) Proc R Soc A 463:385-396; Enghoff MB, Pedersen JOP, Uggerhoj UI, Paling SM, Svensmark H (2011) Geophys Res Lett 38:L09805], demonstrating the theoretical mechanism of this link. In this article, we present an analysis based on convergent cross mapping, which uses observational time series data to directly examine the causal link between CR and year-to-year changes in Global Temperature. Despite a gross correlation, we find no measurable evidence of a causal effect linking CR to the overall 20th-century warming trend. However, on short interannual timescales, we find a significant, although modest, causal effect between CR and short-term, year-to-year variability in Global Temperature that is consistent with the presence of nonlinearities internal to the system. Thus, although CR do not contribute measurably to the 20th-century Global warming trend, they do appear as a nontraditional forcing in the climate system on short interannual timescales.
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dynamical evidence for causality between galactic cosmic rays and interannual variation in Global Temperature
Proceedings of the National Academy of Sciences of the United States of America, 2015Co-Authors: Anastasios A. Tsonis, Kyle L. Swanson, Ethan R Deyle, George Sugihara, Joshua D Verbeten, Geli WangAbstract:Here we use newly available methods to examine the dynamical association between cosmic rays (CR) and Global Temperature (GT) in the 20th-century observational record. We find no measurable evidence of a causal effect linking CR to the overall 20th-century warming trend; however, on short interannual timescales, we find a significant, although modest, causal effect of CR on short-term, year-to-year variability in GT. Thus, although CR clearly do not contribute measurably to the 20th-century Global warming trend, they do appear as a nontraditional forcing in the climate system on short interannual timescales, providing another interesting piece of the puzzle in our understanding of factors influencing climate variability.
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Directional influences on Global Temperature prediction
Geophysical Research Letters, 2012Co-Authors: Geli Wang, Peicai Yang, Xiuji Zhou, Kyle L. Swanson, Anastasios A. TsonisAbstract:[1] There is growing evidence that major climate modes are involved in determining decadal variability in Global mean Temperature. These modes represent major oceanic and atmospheric signals and on decadal scales their collective interplay leads to climate shifts manifesting themselves as regime changes in Global Temperature trend. Here we investigate whether the collective role of these modes is extended within a regime, i.e. to shorter time scales. We apply nonlinear prediction in order to assess directional influences in the climate system. We show evidence that input from four major climate modes from the Atlantic and Pacific improves the prediction of Global Temperature and thus these modes Granger cause Global Temperature. Moreover, we find that this causality is not a result of a particular mode dominating but a result of the nonlinear collective behavior in the network of the four modes.
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Unfolding the relation between Global Temperature and ENSO
Geophysical Research Letters, 2005Co-Authors: Anastasios A. Tsonis, James B. Elsner, Allen G. Hunt, Thomas H. JaggerAbstract:[1] An analysis of Global Temperature and ENSO data indicates that their relationship is more complicated than currently thought. Indeed, it appears that there are two complimenting aspects to this relation. The first (and known) aspect expresses the fact that Global Temperature increases after an El Nino event and a La Nina event follows an El Nino event. Thus, El Nino forces Global Temperature. While this is an important result, it is not the entire picture. If it were, ENSO would be independent of Global Temperature. The second aspect, which is proposed here, suggests a deeper connection between Global Temperature and ENSO. We find that ENSO is not independent and that positive (negative) Global Temperature tendency tends to trigger an El Nino (La Nina). Thus, in a warming climate El Nino events will be more frequent than La Nina events. The methodology presented in this paper may elucidate how realistically coupled ocean-atmosphere models simulate the response of climate to Global change.
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A characteristic time scale in the Global Temperature record
Geophysical Research Letters, 1998Co-Authors: Anastasios A. Tsonis, Paul J. Roebber, James B. ElsnerAbstract:Using modern time series analysis we discover a characteristic time scale in the Global Temperature record. This time scale corresponds to about 20 months and separates processes that promote a trend in the past from processes that reverse this tendency. This characteristic scale has important implications one of which might be that the El Nino/La Nina cycle may act as a mechanism countering the tendency of shorter time scale events to organize a positive or a negative Temperature trend.
Warren G Strand - One of the best experts on this subject based on the ideXlab platform.
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relative outcomes of climate change mitigation related to Global Temperature versus sea level rise
Nature Climate Change, 2012Co-Authors: Gerald A Meehl, Aixue Hu, Claudia Tebaldi, Julie M Arblaster, Warren M Washington, Haiyan Teng, Benjamin M Sanderson, Toby R Ault, Warren G StrandAbstract:A modelling study shows that cutting greenhouse-gas emissions has the potential to stabilize Global Temperature increases, but predicts that sea level will continue to rise for centuries, and rapidly so, unless aggressive mitigation measures are set in place.
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relative outcomes of climate change mitigation related to Global Temperature versus sea level rise
Nature Climate Change, 2012Co-Authors: Gerald A Meehl, Aixue Hu, Claudia Tebaldi, Julie M Arblaster, Warren M Washington, Haiyan Teng, Benjamin M Sanderson, Toby R Ault, Warren G StrandAbstract:A modelling study shows that cutting greenhouse-gas emissions has the potential to stabilize Global Temperature increases, but predicts that sea level will continue to rise for centuries, and rapidly so, unless aggressive mitigation measures are set in place. There is a common perception that, if human societies make the significant adjustments necessary to substantively cut emissions of greenhouse gases, Global Temperature increases could be stabilized, and the most dangerous consequences of climate change could be avoided. Here we show results from Global coupled climate model simulations with the new representative concentration pathway mitigation scenarios to 2300 to illustrate that, with aggressive mitigation in two of the scenarios, Globally averaged Temperature increase indeed could be stabilized either below 2 °C or near 3 °C above pre-industrial values. However, even as Temperatures stabilize, sea level would continue to rise. With little mitigation, future sea-level rise would be large and continue unabated for centuries. Though sea-level rise cannot be stopped for at least the next several hundred years, with aggressive mitigation it can be slowed down, and this would buy time for adaptation measures to be adopted.
