James J. S. Johnson, J.D., Th.D., and Tim Clarey, Ph.D.

An overview of the Milankovitch (or astronomical) ice age theory appears in the May 2020 issue of Physics Today.¹ This theory (hypothesis, really) holds that Earth’s rotational and orbital motions influence Earth’s climate over long ages, pacing the timing of ice ages.

Tim Clarey, Ph.D., and Frank Sherwin, M.A.

A recent study in March 2020 suggested that sulfur dioxide (SO₂) injected into Earth’s stratosphere could fight global warming, with a minimum of adverse effects.^1,2