Reconstruction of annual solar irradiance over the last three millennia

Solar irradiance measurements are limited, spanning only the last few decades, requiring reconstructions to assess solar variability on longer timescales and its impact on Earth’s climate. We present the first physics-based reconstruction of total solar irradiance (TSI) at annual resolution over the last three millennia. The reconstruction is obtained by extending the SATIRE-T model beyond the telescopic era using recently published, annually resolved sunspot number series derived from cosmogenic isotope records. This yields a continuous, physics-based TSI record extending from the satellite era back over the last three millennia, with an annual resolution throughout the pre-telescopic period. Over this full interval, the reconstructed TSI exhibits a maximum difference of 1.04 −0.2 +0.14 W m −2 , defined as the difference between the maximum and minimum of the 50-year running mean values.