Haaga KA, Brendryen J, Diego D, Hannisdal B:. Manuscript preprint available.


Insolation, or the amount of solar radiation reaching the Earth, varies across latitudes, and its importance as a dynamical forcing of global climate is debated. Here we use the intrinsic dynamical information in global sea level reconstructions to show that integrated summer insolation at different latitudes was a significant forcing of global ice volume during the past 800,000 years. Using a model-free approach, we provide an explicit test of the conventional assumption that Northern Hemisphere summer insolation represents the external forcing of the climate system. Our findings empirically support the pivotal role of Northern Hemisphere summer melting predicted by Milankovitch theory, but also demonstrate non-linearity and spatial variability in the orbital forcing of global climate change.

Time series of insolation and global ice volume over the last 800,000 years and the corresponding trajectories in 3-D state space reconstructions.

This study is awaiting publication, but you can check out the preprint on OSF. Code to reproduce all analyses and figures is available here.