Solar minimum deepening: Lower irradiance levels may impact Earth's climate.
The current solar cycle minimum is deeper and broader than recent ones, similar to those in the early 1900s. Best-ever satellite measurements show lower solar irradiance levels in 2008 compared to 1996, with total solar irradiance down by about 200 ppm and EUV irradiance 15% lower. However, these results have uncertainties due to instrument degradation trends. Lower solar magnetic fields and more low-latitude coronal holes support the evidence for lower irradiance during this minimum.