The Pu'u 'O'o volcano on Kilauea, Hawaii. (Credit: USGS)
When scientists talk about millennial-scale climate change, they have to deal with a lot of uncertainty because there is still so much to be learned about the mechanisms that act on such long timescales. However, one Durham University team has suggested that large volcanic eruptions may play a role in mediating the Earth’s hemispheric temperature fluctuations.
Dansgaard-Oeschger events are periods of rapid warming followed by gradual cooling, and previous research has established a strong correlation between these events and volcanic activity in the southern hemisphere. Using data from ice cores, volcanic eruptions and speleothems (stalagmites and stalactites), the authors of this study argued that such large eruptions do not cool the globe uniformly, as previously thought.
Instead, an eruption in the northern hemisphere would cause the local temperature to decrease and the temperature in the southern hemisphere to increase. The local cooling effect is due to sulfates ejected by the volcano that reflect light back into space. This northern hemisphere cooling then causes atmospheric pressure systems to shift to the south, which causes the temperatures there to increase.
Top image: The Pu’u ‘O’o volcano on Kilauea, Hawaii. (Credit: USGS)