(By Francis A. Macdonald, Nicholas L. Swanson-Hysell, Yuem Park, Lorraine Lisiecki, Oliver Jagoutz)
On million-year time scales, Earth's climate state is determined by sources and sinks of carbon to the ocean-atmosphere system. But which specific mechanisms are important in controlling the timing of glacial intervals? Macdonald et al. identify arc-continent collisions in the tropics as a primary control (see the Perspective by Hartmann). They compiled a database of Phanerozoic arc-continent collisions and the latitudinal distribution of ice sheets, showing that ice coverage was greatest when those collisions were most widespread, maximizing global weatherability.
Ice Ages triggered when tropical islands and continents collide (Berkeley News)