Image caption
Reconstruction of total solar irradiance based on sunspot observations since the 1600s. During strong solar cycles, the Sun's total average brightness varies by up to 1 Watt per square meter. Changes in the Sun's overall brightness since the pre-industrial period have been minimal, making a very small contribution to global-scale warming. NOAA Climate.gov image, based on the Climate Data Record by Coddington, et al., 2016.