New research published in the journal Nature Communications sheds light on the causes of a Jurassic ice age some 170 million years ago.
In general, volcanic events are usually associated with periods of warmth which makes a new publication by University of Exeter geologists even that more interesting. Researchers suggest that an ice age during the Jurassic period was caused by restricted ocean currents due to volcanic events. The restricted flow of ocean water meant that heat from the equator wasn’t dispersing north, disrupting the flow of the oceans and changing the climate.
170 million years ago the Earth’s surface was one single super-continent called Pangaea. The land mass had a prominent seaway connecting the warm Tethys seas to the northern regions.
After spending 10 years constructing a record of seawater temperature change using fossil mollusc shells, scientists found that during the same period of the volcanic event Earth experienced a significant and rapid cooling.
Researchers hypothesize that the volcanic event, known as the North Sea Dome, restricted the flow of ocean currents and associated heat northward through the main seaway. Evidence indicates the Jurassic ice age lasted many millions of years until the volcanic activity subsided.
Prof. Stephen Hesselbo, one of the lead authors of the study said, “We tend to think of the Jurassic as a warm ‘greenhouse’ world where high temperatures were governed by high atmospheric carbon dioxide contents. This new study suggests that re-organization of oceanic current patterns may also have triggered large scale climate changes.”
He added, “Although we have known about the occurrence of cold periods during greenhouse times for a while, their origins have remained mysterious. This work suggests a mechanism at play that may also have been important for driving other climate change events in the Jurassic and at other times in Earth history.”
Material provided by University of Exeter.