Solar System Dynamics and Multiyear Droughts of the Western USA

Abstract

The recent addition of orbit-spin coupling torques to atmospheric global circulation models has enabled successful years-in-advance forecasts of global and regional-scale dust storms on Mars. Here we explore the applicability of the orbit-spin coupling mechanism for understanding and forecasting anomalous weather and climate events on Earth. We calculate the time history of orbit-spin coupling torques on the Earth system for the interval from 1860-2040. The torque exhibits substantial variability on decadal to bidecadal timescales. Deep minima recur at intervals from 15-26 years; eight such episodes are documented within the study period prior to 2020. Each of the identified torque minima corresponds in time to an episode of widespread drought in the Western USA extending over several years. The multiyear droughts of the 1930s, the 1950s, the mid-1970s, the early 1990s, and of 2011-2015 were each coincident in time with orbit-spin coupling torque minima. The upcoming torque minimum of 2030 is the deepest such minimum of the 180-yr study interval. A multiyear episode of widespread drought in the Western USA is likely to be underway by 2028 plus or minus 4 years (2 standard deviations). The potential benefits to societies of improved drought predictions justify an immediate high-priority effort to include forcing by orbit-spin coupling within state-of-the-art Earth system GCMs. Future targeted numerical modeling investigations are likely to yield forecasts with considerably lower uncertainties and with much improved temporal resolution in comparison to that obtained here.