1,000 Year Ensemble Reconstructions of Temperature and CO2 Frank, D.C.; Esper, J.; Raible, C.C.; Büntgen, U.; Trouet, V.; Stocker, T.F.; Joos, F. Frank, D.C. Esper, J. Raible, C.C. Büntgen, U. Trouet, V. Stocker, T.F. Joos, F. Air Temperature Reconstruction carbon cycle sensitivity earth science/paleoclimate/climate reconstructions (surface temperature,multiple proxies,percentile,degree Celsius,annual,climate reconstructions,smoothed,composite plus scale,N,5th percentile; smooth: 10 year spline; calibration data set: HADCRUT4) earth science/paleoclimate/climate reconstructions (surface temperature,multiple proxies,percentile,degree Celsius,annual,climate reconstructions,smoothed,composite plus scale,N,40th percentile; smooth: 10 year spline; calibration data set: HADCRUT11) earth science/paleoclimate/climate reconstructions (surface temperature,multiple proxies,percentile,degree Celsius,annual,climate reconstructions,smoothed,composite plus scale,N,55th percentile; smooth: 10 year spline; calibration data set: HADCRUT14) earth science/paleoclimate/climate reconstructions (surface temperature,multiple proxies,percentile,degree Celsius,annual,climate reconstructions,smoothed,composite plus scale,N,85th percentile; smooth: 10 year spline; calibration data set: HADCRUT20) earth science/paleoclimate/climate forcing|ice cores (carbon dioxide,bulk atmosphere,null,parts per million,null,climate forcing|ice cores,smoothed,gas chromatography,N,smooth: 125 year spline) earth science/paleoclimate/climate reconstructions (surface temperature,multiple proxies,percentile,degree Celsius,annual,climate reconstructions,smoothed,composite plus scale,N,30th percentile; smooth: 10 year spline; calibration data set: HADCRUT9) earth science/paleoclimate/climate reconstructions (surface temperature,multiple proxies,percentile,degree Celsius,annual,climate reconstructions,smoothed,composite plus scale,N,97.5th percentile; smooth: 10 year spline; calibration data set: HADCRUT23) earth science/paleoclimate/climate reconstructions (surface temperature,multiple proxies,range upper bound,degree Celsius,annual,climate reconstructions,smoothed,composite plus scale,N,smooth: 10 year spline; calibration data set: HADCRUT25) earth science/paleoclimate/climate forcing|ice cores (carbon dioxide,bulk atmosphere,null,parts per million,null,climate forcing|ice cores,smoothed,gas chromatography,N,smooth: 150 year spline) earth science/paleoclimate/climate reconstructions (surface temperature,multiple proxies,percentile,degree Celsius,annual,climate reconstructions,smoothed,composite plus scale,N,50th percentile; smooth: 10 year spline; calibration data set: HADCRUT13) earth science/paleoclimate/climate reconstructions (surface temperature,multiple proxies,percentile,degree Celsius,annual,climate reconstructions,smoothed,composite plus scale,N,60th percentile; smooth: 10 year spline; calibration data set: HADCRUT15) earth science/paleoclimate/climate reconstructions (surface temperature,multiple proxies,percentile,degree Celsius,annual,climate reconstructions,smoothed,composite plus scale,N,75th percentile; smooth: 10 year spline; calibration data set: HADCRUT18) earth science/paleoclimate/climate reconstructions (surface temperature,multiple proxies,percentile,degree Celsius,annual,climate reconstructions,smoothed,composite plus scale,N,90th percentile; smooth: 10 year spline; calibration data set: HADCRUT21) earth science/paleoclimate/climate forcing|ice cores (carbon dioxide,bulk atmosphere,null,parts per million,null,climate forcing|ice cores,smoothed,gas chromatography,N,smooth: 50 year spline) earth science/paleoclimate/climate forcing|ice cores (carbon dioxide,bulk atmosphere,null,parts per million,null,climate forcing|ice cores,smoothed,gas chromatography,N,smooth: 100 year spline) earth science/paleoclimate/climate reconstructions (surface temperature,multiple proxies,percentile,degree Celsius,annual,climate reconstructions,smoothed,composite plus scale,N,20th percentile; smooth: 10 year spline; calibration data set: HADCRUT7) earth science/paleoclimate/climate reconstructions (surface temperature,multiple proxies,percentile,degree Celsius,annual,climate reconstructions,smoothed,composite plus scale,N,25th percentile; smooth: 10 year spline; calibration data set: HADCRUT8) earth science/paleoclimate/climate reconstructions (surface temperature,multiple proxies,percentile,degree Celsius,annual,climate reconstructions,smoothed,composite plus scale,N,45th percentile; smooth: 10 year spline; calibration data set: HADCRUT12) earth science/paleoclimate/climate reconstructions (surface temperature,multiple proxies,percentile,degree Celsius,annual,climate reconstructions,smoothed,composite plus scale,N,80th percentile; smooth: 10 year spline; calibration data set: HADCRUT19) earth science/paleoclimate/climate reconstructions (surface temperature,multiple proxies,null,degree Celsius,annual,climate reconstructions,anomalized,composite plus scale,N,reference period: 1971-2000 A.D.; calibration data set: HADCRUT3) earth science/paleoclimate/climate reconstructions (surface temperature,multiple proxies,null,degree Celsius,annual,climate reconstructions,anomalized|smoothed,composite plus scale,N,reference period: 1971-2000 A.D.; smooth: 50 year spline; calibration data set: HADCRUT3) earth science/paleoclimate/climate reconstructions (surface temperature,multiple proxies,percentile,degree Celsius,annual,climate reconstructions,smoothed,composite plus scale,N,2.5th percentile; smooth: 10 year spline; calibration data set: HADCRUT3) earth science/paleoclimate/climate reconstructions (surface temperature,multiple proxies,percentile,degree Celsius,annual,climate reconstructions,smoothed,composite plus scale,N,95th percentile; smooth: 10 year spline; calibration data set: HADCRUT22) earth science/paleoclimate/climate reconstructions (surface temperature,multiple proxies,percentile,degree Celsius,annual,climate reconstructions,smoothed,composite plus scale,N,35th percentile; smooth: 10 year spline; calibration data set: HADCRUT10) earth science/paleoclimate/climate reconstructions (surface temperature,multiple proxies,percentile,degree Celsius,annual,climate reconstructions,smoothed,composite plus scale,N,65th percentile; smooth: 10 year spline; calibration data set: HADCRUT16) earth science/paleoclimate/climate reconstructions (surface temperature,multiple proxies,percentile,degree Celsius,annual,climate reconstructions,smoothed,composite plus scale,N,70th percentile; smooth: 10 year spline; calibration data set: HADCRUT17) earth science/paleoclimate/climate forcing|ice cores (carbon dioxide,bulk atmosphere,null,parts per million,null,climate forcing|ice cores,smoothed,gas chromatography,N,smooth: 75 year spline) earth science/paleoclimate/climate reconstructions (surface temperature,multiple proxies,percentile,degree Celsius,annual,climate reconstructions,smoothed,composite plus scale,N,15th percentile; smooth: 10 year spline; calibration data set: HADCRUT6) earth science/paleoclimate/climate reconstructions (surface temperature,multiple proxies,percentile,degree Celsius,annual,climate reconstructions,smoothed,composite plus scale,N,10th percentile; smooth: 10 year spline; calibration data set: HADCRUT5) earth science/paleoclimate/climate reconstructions (surface temperature,multiple proxies,range lower bound,degree Celsius,annual,climate reconstructions,smoothed,composite plus scale,N,smooth: 10 year spline; calibration data set: HADCRUT24) earth science/paleoclimate/climate forcing|ice cores (carbon dioxide,bulk atmosphere,null,parts per million,null,climate forcing|ice cores,smoothed,gas chromatography,N,smooth: 175 year spline) earth science/paleoclimate/climate forcing|ice cores (carbon dioxide,bulk atmosphere,null,parts per million,null,climate forcing|ice cores,smoothed,gas chromatography,N,smooth: 200 year spline) earth science/paleoclimate/climate reconstructions (age,null,null,year Common Era,null,climate reconstructions,null,null,N,null) earth science/paleoclimate/climate reconstructions (surface temperature,multiple proxies,null,degree Celsius,annual,climate reconstructions,anomalized|smoothed,composite plus scale,N,reference period: 1971-2000 A.D.; smooth: 10 year spline; calibration data set: HADCRUT3) earth science/paleoclimate/ice cores (age,null,null,year Common Era,null,ice cores,null,null,N,null) earth science/paleoclimate/climate forcing|ice cores (carbon dioxide,bulk atmosphere,null,parts per million,null,climate forcing|ice cores,composited|smoothed,gas chromatography,N,smooth: 50 year spline) earth science/paleoclimate/reconstructions (Northern Hemisphere>LATITUDE >LONGITUDE ) The processes controlling the carbon flux and carbon storage of the atmosphere, ocean and terrestrial biosphere are temperature sensitive and are likely to provide a positive feedback leading to amplified anthropogenic warming. Owing to this feedback, at timescales ranging from interannual to the 20-100-kyr cycles of Earth's orbital variations, warming of the climate system causes a net release of CO2 into the atmosphere; this in turn amplifies warming. But the magnitude of the climate sensitivity of the global carbon cycle (termed gamma), and thus of its positive feedback strength, is under debate, giving rise to large uncertainties in global warming projections. Here we quantify the median gamma as 7.7 p.p.m.v. CO2 per °C warming, with a likely range of 1.7 - 21.4 p.p.m.v. CO2 per °C. Sensitivity experiments exclude significant influence of pre-industrial land-use change on these estimates. Our results, based on the coupling of a probabilistic approach with an ensemble of proxy-based temperature reconstructions and pre-industrial CO2 data from three ice cores, provide robust constraints for gamma on the policy-relevant multi-decadal to centennial timescales. By using an ensemble of >200,000 members, quantification of gamma is not only improved, but also likelihoods can be assigned, thereby providing a benchmark for future model simulations. Although uncertainties do not at present allow exclusion of gamma calculated from any of ten coupled carbon-climate models, we find that gamma is about twice as likely to fall in the lowermost than in the uppermost quartile of their range. Our results are incompatibly lower (P,0.05) than recent pre-industrial empirical estimates of 40 p.p.m.v. CO2 per °C, and correspondingly suggest 80% less potential amplification of ongoing global warming. STUDY NOTES: Calibration ensemble reconstructions of existing large-scale temperature estimates. Reconstructions were recalibrated to mitigate biases in the choice of the instrumental target, calibration period, and methods which may not adequately preserve the full amplitude of temperature variability. 521 different members were derived and used to define the amplitude of temperature variability. Reconstructions of the atmospheric CO2 concentration from 3 Antarctic ice cores were combined and variability smoothed. The temperature and CO2 reconstructions were combined to constrain the climate sensitivity of the global carbon cycle. Temperature reconstructions are provided in Deg. C w.r.t 1971-2000, with the column header indicating the large-scale reconstruction, the first year of calibration, and the last year of calibration. The CO2 data are provided in ppmv. See publication for details. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Frank, D.C. Investigator : Esper, J. Investigator : Raible, C.C. Investigator : Büntgen, U. Investigator : Trouet, V. Investigator : Stocker, T.F. Investigator : Joos, F. 2010-04-02 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/10437 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/frank2010/ensembles-percentiles.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/frank2010/ensembles-calib-raw.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/frank2010/ensembles-10yearsmth.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/frank2010/smoothedco2.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/frank2010/readme-frank2010.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/frank2010/ensembles-50yearsmth.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/frank2010/ensembles-percentiles.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/frank2010/ensembles-calib-raw.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/frank2010/ensembles-10yearsmth.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/frank2010/smoothedco2.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/frank2010/readme-frank2010.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/frank2010/ensembles-50yearsmth.txt English https://www.ncdc.noaa.gov/paleo/study/10437 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/frank2010/ensembles-percentiles.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/frank2010/ensembles-calib-raw.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/frank2010/ensembles-10yearsmth.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/frank2010/smoothedco2.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/frank2010/readme-frank2010.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/frank2010/ensembles-50yearsmth.txt Frank, D.C., J. Esper, C.C. Raible, U. Büntgen, V. Trouet, B. Stocker, and F. Joos. 2010. Ensemble reconstruction constraints on the global carbon cycle sensitivity to climate. Nature, Vol. 463, pp.527-532, 28 January 2010. doi:10.1038/nature08769 START YEAR: 1000 AD * END YEAR: 1995 AD -180 0 180 90