Three of the five coldest decades in the Common Era (CE) occurred in the 540s, 1450s, and 1600s. It has been determined that massive volcanic eruptions caused these cold pulses in each instance. This resulted in volcanic sulfate particles reflecting incoming sunlight.
However, it was unknown where the volcanic eruptions came from and how much sulfate they released into the high atmosphere.
The isotopes offered a unique fingerprint of the proportion of sulfate that made it into the upper atmosphere. The findings show that the most significant historical cooling periods were caused by volcanic eruptions at high latitudes when correlated with tree-ring climate data. The results also imply that summer temperatures may be susceptible to high-latitude volcanic eruptions, as the amount of sulfate injected into the stratosphere by these eruption episodes may have been around half of what was previously estimated.
Dr Burke said, “Our data show that when Earth’s climate gets altered, other parts of the climate system can amplify this initial change strongly. High latitudes feel these amplified climate changes particularly strongly, which is concerning given how rapidly these regions are changing today.”
The authors claim that the sensitivity of temperature to high-latitude eruptions emphasizes how important climate feedback are in amplifying changes in the global climate, including sea ice extent and ocean heat content.