Natural factors: Variations in the Sun’s output

  • Data: Lean and Rind, 2008

  • SOHO (ESA & NASA)

  • Data: Lean and Rind, 2008

  • NASA

  • NASA / JSC

    The Sun’s output varies over time. Scientists track these changes using observations of sunspots and (more recently) satellite measurements. Average solar energy has hardly changed in the past 50 years and may even have had a recent cooling effect. The Sun cannot account for the increase in global temperature observed since 1970.