Reconstruction of annual solar irradiance over the last three millennia

TL;DR

This study provides the first physics-based, annual-resolution reconstruction of total solar irradiance over the last three millennia, extending beyond direct measurements using sunspot and isotope data.

Contribution

It extends the SATIRE-T model with cosmogenic isotope data to produce a continuous, high-resolution TSI record over three millennia, including pre-telescopic periods.

Findings

Reconstructed TSI shows a maximum difference of about 1.04 W/m^2 over three millennia.

The record is continuous and extends from the satellite era back to 3000 years ago.

Annual resolution enables detailed analysis of solar variability over long timescales.

Abstract

Solar irradiance measurements are limited to 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 annual resolution throughout the pre-telescopic period. Over the full three-millennia interval, the reconstructed TSI exhibits a maximum difference of $1.04_{-0.2}^{+0.14}\,\mathrm{W\,m^{-2}}$, defined as the difference between the maximum and minimum of the 50-yr running mean values.