Episode 141: Natural Climate Change

Solar Forcing

James Fodor discusses the concept of solar forcing, where changes in the sun's output lead to variations in Earth's climate. He explains that while the sun has been warming over millions of years, this long-term trend does not account for recent climate changes. The sunspot cycle, an 11-year cycle of solar output variation, is too short and minor to significantly impact global temperatures 1.

The sunspot cycle is both too small in magnitude, but also too short in time to account for any changes in average global temperatures over the past century.

--- James Fodor

Fodor notes that recent slight reductions in solar irradiance have contributed minimally to global cooling, but these effects are negligible compared to other factors 2.

   

Long-Term Changes

Fodor also addresses long-term changes in the sun's output, such as the young faint sun paradox, which questions why Earth was hotter in the distant past despite a fainter sun. He explains that while the sun's radiation has increased significantly over millions of years, these changes are too gradual to explain recent temperature fluctuations 1.

The sun is gradually increasing its radiation output quite significantly, but that's happening over a period of time of hundreds of millions of years.

--- James Fodor

These long-term solar changes are important for understanding paleoclimates but do not account for the rapid warming observed in the last century 2.