Sun's Variable Output: Implications for Earth's Climate

Big Bear Solar Observatory Philip R. Goode Big Bear Solar Observatory New Jersey Institute of Technology

Irradiance Changes • Blue curve is solar cycle • Red curve adds purported long-term variation • Temperature changes from NCAR model • Yellow line limit from physics of irradiance change Big Bear Solar Observatory

Origin of Sun’s Variable Output • Seismic data from SoHO/MDI provide most precise measure of solar variability • Physical picture is that rising solar activity blocks heat and convective flows, while corregating the solar surface making it a more effective radiator • Active sun is cooler, corregated, slightly smaller and more irradiant • Inactive sun is warmer, smoother, slightly larger and minimally irradiant Big Bear Solar Observatory

Implications of Limit • Earth is responding to more subtle changes in Sun, which imprint the solar cycle and longer term wanderings of solar activity • Changes in solar wind induces some unknown changes at the Earth • A new burden on the climate models Big Bear Solar Observatory

Earthshine Plus ISCCP Conclusions • Earth’s Reflectance has increased over the last five years • Clouds have re-arranged themselves in the same period so that their net cooling effect is reduced. • Earth can warm with less sunlight Big Bear Solar Observatory

Sun's Variable Output: Implications for Earth's Climate