Philippine E-Journals

Astrophysical Drivers of Climate Cycles

Emmanuel T. Rodulfo | Eunbin Yim

 

Abstract:

This review aims to provide a broader perspective to the current interest on climate variability by revisiting the astrophysical mechanisms that dictate our planet’s climate cycles. The intrinsic variability of the sun’s power output is indisputably a dominant contributor to global temperature as its irradiance pulsates roughly every ~10.7 years, modulated by a longer quasi periodic ~186-year cycle manifested by the Oort, Wolf, Sporer, Maunder; and Dalton solar minima. The Little Ice Age (1350-1850) was purportedly triggered by the five-decade-long Maunder Minimum (1645-1715). Quite apart from this intrinsic variability of the sun, the Milankovi? hypothesis attributes the amount of incoming solar radiation (insolation) to Earth’s spin-orbit dynamics. The superposition of the ~100ka oscillation in the planet’s orbital eccentricity, the ~22ka apsidal precession, and the ~41ka oscillation of axial obliquity, has been known to correlate with the time-rate of change of global temperature, which appear to explain the alternating sequence of glacial and interglacial epochs (1ka=1000y). The current interglacial period (the Holocene) has already idled for more than a millennium beyond the mean duration. In order to provide a quantitative connection between insolation and the astrophysical drivers, we describe a streamlined model that allows one to calculate insolation as a function of the the varying solar output and Milankovi? parameters. Through this quasi-theoretical review, we hope to shed some light on the uncertainties that currently plague climate science.