Northern Hemisphere 4000 Year Temperature Reconstructions Kobashi, T.; Goto-Azuma, K.; Box, J.E.; Gao, C.-C.; Nakaegawa, T. Kobashi, T. Goto-Azuma, K. Box, J.E. Gao, C.-C. Nakaegawa, T. Air Temperature Reconstruction Arctic Arctic Oscillation (AO) North Atlantic Oscillation earth science/paleoclimate/climate forcing (greenhouse gas forcing,null,null,watt per square meter,null,climate forcing,anomalized,null,N,null) earth science/paleoclimate/climate reconstructions|ice cores (surface temperature,delta 15N excess,one standard deviation upper bound,degree Celsius,null,climate reconstructions|ice cores,anomalized,null,N,northern hemisphere) earth science/paleoclimate/climate reconstructions|ice cores (surface temperature,delta 15N excess,null,degree Celsius,null,climate reconstructions|ice cores,anomalized,null,N,northern high latitudes) earth science/paleoclimate/climate reconstructions|ice cores (surface temperature,delta 15N excess,one standard deviation upper bound,degree Celsius,null,climate reconstructions|ice cores,anomalized,null,N,northern high latitudes) earth science/paleoclimate/climate forcing (volcanic forcing,null,null,watt per square meter,null,climate forcing,anomalized|smoothed,null,N,51 year running means) earth science/paleoclimate/climate reconstructions|ice cores (surface temperature,delta 15N excess,one standard deviation lower bound,degree Celsius,null,climate reconstructions|ice cores,anomalized,null,N,northern hemisphere) earth science/paleoclimate/climate reconstructions|ice cores (age,null,null,year Common Era,null,climate reconstructions|ice cores,null,null,N,null) earth science/paleoclimate/climate forcing (solar irradiance,null,null,watt per square meter,null,climate forcing,anomalized,null,N,null) earth science/paleoclimate/climate forcing (anthropogenic aerosol forcing,null,null,watt per square meter,null,climate forcing,anomalized,null,N,null) earth science/paleoclimate/climate forcing (volcanic forcing,null,null,watt per square meter,null,climate forcing,anomalized|raw,null,N,null) earth science/paleoclimate/climate reconstructions|ice cores (surface temperature,delta 15N excess,null,degree Celsius,null,climate reconstructions|ice cores,anomalized,null,N,northern hemisphere) earth science/paleoclimate/climate reconstructions|ice cores (surface temperature,delta 15N excess,one standard deviation lower bound,degree Celsius,null,climate reconstructions|ice cores,anomalized,null,N,northern high latitudes) earth science/paleoclimate/paleoclimatic modeling (surface temperature,null,null,degree Celsius,null,paleoclimatic modeling,null,null,N,northern hemisphere) earth science/paleoclimate/paleoclimatic modeling (surface temperature,null,null,degree Celsius,null,paleoclimatic modeling,null,null,N,northern high latitudes) earth science/paleoclimate/reconstructions (Northern Hemisphere>LATITUDE >LONGITUDE ) Precise understanding of Greenland temperature variability is important in two ways. First, Greenland ice sheet melting associated with rising temperature is a major global sea level forcing, potentially affecting large populations in coming centuries. Second, Greenland temperatures are highly affected by North Atlantic Oscillation/Arctic Oscillation (NAO/AO) and Atlantic multidecadal oscillation (AMO). In our earlier study, we found that Greenland temperature deviated negatively (positively) from northern hemispheric (NH) temperature trend during stronger (weaker) solar activity owing to changes in atmospheric/oceanic changes (e.g. NAO/AO) over the past 800 yr (Kobashi et al., 2013). Therefore, a precise Greenland temperature record can provide important constraints on the past atmospheric/oceanic circulation in the region and beyond. Here, we investigated Greenland temperature variability over the past 4000 yr reconstructed from argon and nitrogen isotopes from trapped air in a GISP2 ice core, using a one-dimensional energy balance model with orbital, solar, volcanic, greenhouse gas, and aerosol forcings. The modelled northern Northern Hemisphere (NH) temperature exhibits a cooling trend over the past 4000 yr as observed for the reconstructed Greenland temperature through decreasing annual average insolation. With consideration of the negative influence of solar variability, the modelled and observed Greenland temperatures agree with correlation coefficients of r = 0.34-0.36 (p = 0.1-0.04) in 21 yr running means (RMs) and r = 0.38-0.45 (p = 0.1-0.05) on a centennial timescale (101 yr RMs). Thus, the model can explain 14 to 20% of variance of the observed Greenland temperature in multidecadal to centennial timescales with a 90-96% confidence interval, suggesting that a weak but persistent negative solar influence on Greenland temperature continued over the past 4000 yr. Then, we estimated the distribution of multidecadal NH and northern high-latitude temperatures over the past 4000 yr constrained by the climate model and Greenland temperatures. Estimated northern NH temperature and NH average temperature from the model and the Greenland temperature agree with published multi-proxy temperature records with r = 0.35-0.60 in a 92-99% confidence interval over the past 2000 yr. We found that greenhouse gases played two important roles over the past 4000 yr for the rapid warming during the 20th century and slightly cooler temperature during the early period of the past 4000 yr. Lastly, our analysis indicated that the current average temperature (1990-2010) or higher temperatures occurred at a frequency of 1.3 times per 1000 yr for northern high latitudes and 0.36 times per 4000 yr for NH temperatures, respectively, indicating that the current multidecadal NH temperature (1990-2010) is more likely unprecedented than not (p = 0.36) for the past 4000 yr. STUDY NOTES: Northern Hemisphere (NH) and northern high latitude (NHL) temperature anomalies (C) over the past 4000 years. A one dimensional energy balance model was applied to investigate Greenland temperature variability over the past 4000 years with reconstructed climate forcing. North Hemispheric average temperature and northern high latitude temperature over the past 4000 years were also reconstructed, constrained by the model and Greenland temperature. Reconstructed climate forcing (greenhouse gas, solar, volcanic, aerosol) are included in the dataset as well as the model outputs. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Kobashi, T. Investigator : Goto-Azuma, K. Investigator : Box, J.E. Investigator : Gao, C.-C. Investigator : Nakaegawa, T. 2013-11-18 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/15535 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/kobashi2013b/kobashi2013nh.xlsx https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/kobashi2013b/kobashi2013nh.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/kobashi2013b/kobashi2013nh.xlsx https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/kobashi2013b/kobashi2013nh.txt English https://www.ncdc.noaa.gov/paleo/study/15535 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/kobashi2013b/kobashi2013nh.xlsx https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/kobashi2013b/kobashi2013nh.txt T. Kobashi, K. Goto-Azuma, J.E. Box, C.-C. Gao, and T. Nakaegawa2013Causes of Greenland temperature variability over the past 4000 yr: implications for northern hemispheric temperature changesClimate of the Past952299-231710.5194/cp-9-2299-2013http://www.clim-past.net/9/2299/2013/cp-9-2299-2013.html START YEAR: -2239 AD * END YEAR: 2000 AD -180 0 180 90