Ancient Antarctic volcanic eruptions sparked climate change

Washington: A series of volcanic eruptions in Antarctica over a period of 192 years may have accelerated the deglaciation event and onset of the most rapid, widespread climate change in the Southern Hemisphere that took place about 17,700 years ago, a study has found.

Climate changes that began about 17,700 years ago included a sudden poleward shift in westerly winds encircling Antarctica with corresponding changes in sea ice extent, ocean circulation, and ventilation of the deep ocean. Evidence of these changes is found in many parts of the Southern Hemisphere and in different paleoclimate archives, but what prompted these changes has remained largely unexplained.

"Detailed chemical measurements in Antarctic ice cores show that massive, halogen-rich eruptions from the West Antarctic Mt Takahe volcano coincided exactly with the onset of the most rapid, widespread climate change in the Southern Hemisphere during the end of the last ice age and the start of increasing global greenhouse gas concentrations," said Joseph R McConnell, from the Desert Research Institute in the US.

"We postulate that these halogen-rich eruptions created a stratospheric ozone hole over Antarctica that, analogous to the modern ozone hole, led to large-scale changes in atmospheric circulation and hydroclimate throughout the Southern Hemisphere," McConnell said.

"These changes initiated the shift from a largely glacial to a largely interglacial climate state. The probability that this was just a coincidence is negligible," he said. Furthermore, the fallout from these eruptions - containing elevated levels of hydrofluoric acid and toxic heavy metals - extended at least 2,800 kilometres from Mt Takahe and likely reached southern South America.