Volcanic activity linked to Earth’s orbital cycles

Ars Technica : Cycles in Earth’s orbit are known to have driven changes in climate by altering the amount of sunlight reaching Earth. A new analysis of geologic records shows that the cycles may also have influenced the rate of volcanic activity. Using sediment cores collected from the sea floor around the Pacific Ocean’s Ring of Fire, researchers from Germany and the US created a record of volcanic activity over the past million years. Based on that record, they identified cycles of activity that aligned with several of the known orbital cycles affecting climate. The most significant was the 41 000-year cycle in Earth’s axial tilt. In their paper , the researchers suggest that the volcanic activity could be connected to crust stress caused by glacial cycles. As sea levels rise or glaciers grow, the water exerts more pressure on the crust, pushing it downward and causing nearby areas of the crust to bulge outward. In a simulation of crust stresses during the last ice age, the researchers found a level of volcanic activity similar to that recorded in Central America. They also noted that the peaks of volcanic activity lagged behind the peaks in climate changes, which they indicate makes sense because of the slower response times of crust stresses.