March/April Geological Society of America Bulletin media highlights

Keywords: glacial deposits, moraines, climate, Milankovitch, Last Glacial Maximum, cosmogenic elements, beryllium.

Periodic changes in Earth’s orbit are now well established as drivers of long-term global climate change, but the influence that each hemisphere may have on the other has been a subject of debate. The last global ice age reached its maximum around 20 thousand years ago, when summer sunshine was at a minimum in the Northern Hemisphere—leading to the hypothesis that the Northern Hemisphere drives global climate. However, recent work in temperate parts of the Southern Hemisphere suggest an onset of the ice age maximum there as early as 30 thousand years ago, when local summer sunshine was at a minimum. The results presented by Sutherland et al. support an early onset of glacial conditions in New Zealand and show that previous glacial advances at 60 and 80 thousand years ago occurred during the two previous Southern Hemisphere summer-sunshine minima. It seems that local changes in summer sunshine, caused by changes in Earth’s orbit, have been an important driver of Southern Hemisphere climate.

Mode and tempo of the Paleocene-Eocene thermal maximum in an expanded section from the Venetian pre-Alps
Luca Giusberti, University of Padova, Department of Geology, Paleontology and Geophysics, Padova 35137, Italy; et al. Pages 391-412.

Keywords: Paleocene-Eocene thermal maximum, carbon isotope record, central western Tethys, stratigraphy, geochemistry, mineralogy, chronology, silicate pump.