By analyzing stalagmites, a team of Caltech researchers has determined that the climate signature in the tropics through four glacial cycles looks different in some ways and similar in others when compared to the climate signature at high latitudes. The results suggest that Earth's climate system might have two modes of responding to significant changes. 

The second-largest mass extinction in Earth's history coincided with a short but intense ice age. Although it has long been agreed that the so-called Late Ordovician mass extinction was related to climate change, exactly how the change produced the extinction has not been known. Now, a team led by Caltech scientists has determined that the majority of extinctions were caused by habitat loss due to falling sea levels and cooling of the tropical oceans.

The field of study of Andrew Thompson, assistant professor of environmental science and engineering at Caltech, presents not only theoretical challenges but logistical ones as well. That's because he is interested in the circulation and ecology of the Southern Ocean and the role it plays in global climate. The hostile environment of this area makes long-term research difficult, so he's part of a team that is seeking to monitor the region with autonomous underwater vehicles called gliders.