Ancient observations link changes in Sun's brightness and Earth's climate


  • Kevin D. Pang,

  • Kevin K. Yau


From the frequencies of sunspot and aurora sightings, abundance of carbon-14 in the rings of long-lived trees, and beryllium-10 in the annual ice layers of polar ice cores, we have reconstructed the history of a variable Sun. In the last 1,800 years, the Sun has gone through nine cycles of changes in brightness. While these long-term variations account for less than 1%of the total irradiance, there is clear evidence that they affect the Earth's climate.