Crowley 2000 Causes of Climate Change Over the Past 1000 Years Crowley, T.J. Crowley, T.J. Air Temperature Reconstruction earth science/paleoclimate/climate forcing (volcanic forcing,null,null,watt per square meter,null,climate forcing,null,null,N,null) earth science/paleoclimate/climate forcing (solar irradiance,null,null,watt per square meter,null,climate forcing,null,null,N,C14 Bard/Lean splice) earth science/paleoclimate/paleoclimatic modeling (temperature,null,null,degree Celsius,null,paleoclimatic modeling,anomalized,null,N,response to all forcings calculated at a sensitivity of 2.0°C for a doubling of CO2) earth science/paleoclimate/paleoclimatic modeling (age,null,null,year Common Era,null,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/climate forcing (anthropogenic aerosol forcing,null,null,watt per square meter,null,climate forcing,null,null,N,null) earth science/paleoclimate/climate reconstructions (temperature,null,null,degree Celsius,null,climate reconstructions,smoothed,null,N,Crowley and Lowery Northern Hemisphere time series spliced onto smoothed Jones instrumental time series) earth science/paleoclimate/paleoclimatic modeling (temperature,null,null,degree Celsius,null,paleoclimatic modeling,anomalized,null,N,response to solar forcing (Be10) calculated at a sensitivity of 2.0°C for a doubling of CO2) earth science/paleoclimate/climate reconstructions (temperature,null,null,degree Celsius,null,climate reconstructions,smoothed,null,N,11-point smoothed Mann et al. Northern Hemisphere time series) earth science/paleoclimate/climate reconstructions (temperature,null,null,degree Celsius,null,climate reconstructions,null,null,N,slight modification to original Crowley and Lowery series) earth science/paleoclimate/paleoclimatic modeling (temperature,null,null,degree Celsius,null,paleoclimatic modeling,anomalized,null,N,response to solar forcing (14C Stv) calculated at a sensitivity of 2.0°C for a doubling of CO2) earth science/paleoclimate/climate forcing (solar irradiance,null,null,watt per square meter,null,climate forcing,null,null,N,Be10/Lean splice) earth science/paleoclimate/paleoclimatic modeling (temperature,null,null,degree Celsius,null,paleoclimatic modeling,anomalized,null,N,response to greenhouse gas forcing calculated at a sensitivity of 2.0°C for a doubling of CO2) earth science/paleoclimate/climate forcing (age,null,null,year Common Era,null,climate forcing,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (temperature,null,null,degree Celsius,null,paleoclimatic modeling,anomalized|smoothed,null,N,response to volcanic and solar (14C Bard) forcing calculated at a sensitivity of 2.0°C for a doubling of CO2) earth science/paleoclimate/paleoclimatic modeling (temperature,null,null,degree Celsius,null,paleoclimatic modeling,anomalized,null,N,response to volcanic forcing calculated at a sensitivity of 2.0°C for a doubling of CO2) earth science/paleoclimate/climate forcing (solar irradiance,null,null,watt per square meter,null,climate forcing,null,null,N,C14 resid/Lean splice) earth science/paleoclimate/climate forcing (greenhouse gas forcing,null,null,watt per square meter,null,climate forcing,null,null,N,carbon dioxide) earth science/paleoclimate/climate reconstructions (age,null,null,year Common Era,null,climate reconstructions,null,null,N,null) earth science/paleoclimate/climate reconstructions (temperature,null,two standard deviations,degree Celsius,null,climate reconstructions,smoothed,null,N,11-point smoothed Mann et al. Northern Hemisphere time series; adjusted for autocorrelation) earth science/paleoclimate/paleoclimatic modeling (temperature,null,null,degree Celsius,null,paleoclimatic modeling,anomalized,null,N,response to solar forcing (14C Bard) calculated at a sensitivity of 2.0°C for a doubling of CO2) earth science/paleoclimate/paleoclimatic modeling (temperature,null,null,degree Celsius,null,paleoclimatic modeling,anomalized,null,N,response to tropospheric aerosol forcing calculated at a sensitivity of 2.0°C for a doubling of CO2) earth science/paleoclimate/model (Global>LATITUDE >LONGITUDE ) Recent reconstructions of Northern Hemisphere temperatures and climate forcing over the past 1000 years allow the warming of the 20th century to be placed within a historical context and various mechanisms of climate change to be tested. Comparisons of observations with simulations from an energy balance climate model indicate that as much as 41 to 64% of preanthropogenic (pre-1850) decadal-scale temperature variations was due to changes in solar irradiance and volcanism. Removal of the forced response from reconstructed temperature time series yields residuals that show similar variability to those of control runs of coupled models, thereby lending support to the models' value as estimates of low-frequency variability in the climate system. Removal of all forcing except greenhouse gases from the ?1000-year time series results in a residual with a very large late-20th-century warming that closely agrees with the response predicted from greenhouse gas forcing. The combination of a unique level of temperature increase in the late 20th century and improved constraints on the role of natural variability provides further evidence that the greenhouse effect has already established itself above the level of natural variability in the climate system. A 21st-century global warming projection far exceeds the natural variability of the past 1000 years and is greater than the best estimate of global temperature change for the last interglacial. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Crowley, T.J. 2000-07-14 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/6103 https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/crowley2000/readme_crowley2000.txt https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/crowley2000/ https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/crowley2000/readme_crowley2000.txt https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/crowley2000/ English https://www.ncdc.noaa.gov/paleo/study/6103 https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/crowley2000/readme_crowley2000.txt https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/crowley2000/ Crowley, T.J. 2000. Causes of Climate Change Over the Past 1000 Years. Science, 289(5477), 270-277. doi:10.1126/science.289.5477.270. START YEAR: 1000 AD * END YEAR: 1998 AD -180 -90 180 90