Links between annual, Milankovitch and continuum temperature variability

Abstract

Climatic processes are intimately coupled so that understanding variability at any one time-scale requires some understanding of the whole. Spectra of Earth’s surface temperature exemplify this interdependence, having a continuum of variability following a power-law scaling1–7. But while specific modes of interannual variability are relatively well understood8, 9, the general controls on continuum variability are uncertain and usually described as purely stochastic processes10–13. Here we show that power-laws scale with the size of annual (1 yr) and Milankovitch period (23,000 and 41,000 yr) cycles. The annual cycle corresponds to scaling at monthly to decadal periods, while millennial and longer periods are tied to the Milankovitch cycles. Thus the annual, Milankovitch, and continuum of temperature variability together represent the response to deterministic insolation forcing. The identification of a deterministic control on the continuum provides insight into the mechanisms governing interannual and longer period climate variability.