Volcanic eruption-temperature link studied

NEW YORK, Jan. 6 (UPI) -- Volcanic eruptions during the past 450 years may have temporarily cooled tropical weather but global warming may have masked the effects, U.S. researchers said.

A study by climate researchers from New York's Columbia University and universities in Scotland also found higher latitudes can be even more sensitive to volcanic activity.

Large eruptions have lowered temperatures at higher latitudes in recent centuries because volcanic particles reflect sunlight back into space, the researchers said in a news release issued by Columbia.

In this study on how the tropics have responded to volcanism, researchers studied tree rings, which can grow thinner in years when temperatures fall.

"This is significant because it gives us more information about how tropical climate responds to forces that alter the effects solar radiation," said lead author Rosanne D'Arrigo, a scientist at the Tree Ring Lab at Columbia University's Lamont-Doherty Earth Observatory.

Besides tree rings, researchers analyzed ice cores from alpine glaciers and corals taken from tropical waters, the university said. All indicators showed low-latitude temperatures fell for several years after major tropical volcanic eruptions.

D'Arrigo said the study indicated higher latitudes may be more sensitive than the tropics because feedback mechanisms make them more vulnerable to temperature shifts.

Authors said eruptions in the 20th century have had less obvious effects in the tropics. They suggested reasons may include fewer major events and "the damping effect of large-scale 20th-century warming."