Solar Variability Over the Last 3000 Years Usoskin, I.G.; Hulot, G.; Gallet, Y.; Roth, R.; Licht, A.; Joos, F.; Kovaltsov, G.A.; Thébault, E.; Khokhlov, A. Usoskin, I.G. Hulot, G. Gallet, Y. Roth, R. Licht, A. Joos, F. Kovaltsov, G.A. Thébault, E. Khokhlov, A. earth science/paleoclimate/climate forcing (solar modulation potential,null,95% confidence interval upper bound,megavolt,null,climate forcing,null,null,N,null) earth science/paleoclimate/climate forcing (sunspot number,null,95% confidence interval lower bound,count,null,climate forcing,null,null,N,null) earth science/paleoclimate/climate forcing (sunspot number,null,95% confidence interval upper bound,count,null,climate forcing,null,null,N,null) earth science/paleoclimate/climate forcing (age,null,null,year Common Era,null,climate forcing,null,null,N,null) earth science/paleoclimate/climate forcing (solar modulation potential,null,95% confidence interval lower bound,megavolt,null,climate forcing,null,null,N,null) earth science/paleoclimate/climate forcing (solar modulation potential,null,null,megavolt,null,climate forcing,null,null,N,null) earth science/paleoclimate/climate forcing (sunspot number,null,null,count,null,climate forcing,null,null,N,null) earth science/paleoclimate/climate forcing (Global>LATITUDE >LONGITUDE ) Aims. The Sun shows strong variability in its magnetic activity, from Grand minima to Grand maxima, but the nature of the variability is not fully understood, mostly because of the insufficient length of the directly observed solar activity records and of uncertainties related to long-term reconstructions. Here we present a new adjustment-free reconstruction of solar activity over three millennia and study its different modes. Methods. We present a new adjustment-free, physical reconstruction of solar activity over the past three millennia, using the latest verified carbon cycle, 14C production, and archeomagnetic field models. This great improvement allowed us to study different modes of solar activity at an unprecedented level of details. Results. The distribution of solar activity is clearly bi-modal, implying the existence of distinct modes of activity. The main regular activity mode corresponds to moderate activity that varies in a relatively narrow band between sunspot numbers 20 and 67. The existence of a separate Grand minimum mode with reduced solar activity, which cannot be explained by random fluctuations of the regular mode, is confirmed at a high confidence level. The possible existence of a separate Grand maximum mode is also suggested, but the statistics is too low to reach a confident conclusion. Conclusions. The Sun is shown to operate in distinct modes - a main general mode, a Grand minimum mode corresponding to an inactive Sun, and a possible Grand maximum mode corresponding to an unusually active Sun. These results provide important constraints for both dynamo models of Sun-like stars and investigations of possible solar influence on Earth's climate. STUDY NOTES: Solar variability, reconstructed from 14C data (Roth and Joos, 2013) using new archeomagnetic data (Licht et al., 2013) NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Usoskin, I.G. Investigator : Hulot, G. Investigator : Gallet, Y. Investigator : Roth, R. Investigator : Licht, A. Investigator : Joos, F. Investigator : Kovaltsov, G.A. Investigator : Thébault, E. Investigator : Khokhlov, A. 2015-04-26 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/18475 https://www1.ncdc.noaa.gov/pub/data/paleo/climate_forcing/solar_variability/usoskin2014solar.txt https://www1.ncdc.noaa.gov/pub/data/paleo/climate_forcing/solar_variability/usoskin2014solar.txt English https://www.ncdc.noaa.gov/paleo/study/18475 https://www1.ncdc.noaa.gov/pub/data/paleo/climate_forcing/solar_variability/usoskin2014solar.txt Usoskin, I.G; Hulot, G; Gallet, Y.; Roth, R.; Licht, A.; Joos, F.; Kovaltsov, G.A.; Thébault, E.; Khokhlov, A.2014Evidence for distinct modes of solar activityAstronomy and AstrophysicsL1056210.1051/0004-6361/201423391http://www.aanda.org/articles/aa/abs/2014/02/aa23391-14/aa23391-14.html START YEAR: -1145 AD * END YEAR: 1945 AD -180 -90 180 90