Ice cores show volcanic eruptions and cold climate strongly linked

Researchers find new evidence that large eruptions were responsible for cold temperature extremes recorded since early Roman times
It is well known that large volcanic eruptions contribute to climate variability. However, quantifying these contributions has proven challenging due to inconsistencies in both historic atmospheric data observed in polar ice cores and corresponding temperature variations seen in climate indicators such as tree rings.

Published today in the journal Nature, a new study by a team of international scientists, including those from British Antarctic Survey, resolves these inconsistencies with a new reconstruction of the timing and changes in temperature of the atmosphere of nearly 300 individual volcanic eruptions extending as far back as the early Roman period.
“Using new records we are able to show that large volcanic eruptions in the tropics and high latitudes were the dominant drivers of climate variability, responsible for numerous and widespread summer cooling extremes over the past 2,500 years,” explains Dr Michael Sigl, the paper’s lead author, assistant research professor at DRI and postdoctoral fellow with the Paul Scherrer Institute in Switzerland.
“These cooler temperatures were caused by large amounts of volcanic sulfate particles injected into the upper atmosphere,” Sigl added, “shielding the Earth”s surface from incoming solar radiation.”
The study shows that 15 of the 16 coldest summers recorded between 500 BC and 1,000 AD followed large volcanic eruptions — with four of the coldest occurring shortly after the largest volcanic events found in record.