The history of the earth has been a history of constant climate change, as the planet enters and leaves long ice ages. Scientists have noted volcanic eruptions tended to increase as glaciers melted. A study published in 2017 in the journal Geology has studied how glacial changes have affected volcanic activity.
The study focused on eruptions in Iceland about 5,500 to 4,500 years ago, when Earth’s climate cooled and glaciers grew, but hadn't become a complete ice age. Scientists studied the volcanic ash that fell into nearby lakes and peat-bogs. The scientists then matched the volcanic ash records to eruptions of Icelandic volanoes. When the two were compared, there was a link between the reduction of glacial size and volcanic eruptions.
“There’s a big change in the record in the mid-Holocene [epoch], where we see no volcanic ash in Europe and very little in Iceland,” says study author Graeme Swindles, an associate professor of Earth system dynamics at the University of Leeds. “This seems to overlap with a time where there’s cold climate conditions, which would have favored glacial advance in Iceland.”
Julie Schindlbeck, a volcanologist at Heidelberg University in Germany, says the work shows “maybe even small changes in ice volume can really affect volcanism.”
NASA's EarthData page discusses the effects that volcanic ash has on climate change.
Large-scale volcanic activity may last only a few days, but the massive outpouring of gases and ash can influence climate patterns for years. Sulfuric gases convert to sulfate aerosols, sub-micron droplets containing about 75 percent sulfuric acid. Following eruptions, these aerosol particles can linger as long as three to four years in the stratosphere.
Major eruptions alter the Earth's radiative balance because volcanic aerosol clouds absorb terrestrial radiation, and scatter a significant amount of the incoming solar radiation, an effect known as "radiative forcing" that can last from two to three years following a volcanic eruption.
"Volcanic eruptions cause short-term climate changes and contribute to natural climate variability," says Georgiy Stenchikov, a research professor with the Department of Environmental Sciences at Rutgers University. "Exploring effects of volcanic eruption allows us to better understand important physical mechanisms in the climate system that are initiated by volcanic forcing."