Tuesday, January 31, 2012

Little Ice Age result of volcanic eruptions, new study says

Sequences of explosive volcanic eruptions in the tropics were the likely trigger for the Little Ice Age, according to a new study.

The research attempts to answer two longstanding questions swirling around the roughly 400-year span of slightly cooler-than normal temperatures: Exactly when did it begin? And what was its initial trigger?

Previous estimates for the onset of the Little Ice Age range from as early as the late 1200s to as late as the 1500s, the research team notes. Globally, temperatures averaged a modest 0.6 degrees Celsius, or about 1 degree Fahrenheit cooler than usual.

But regionally, cooling could be profound. Glaciers in the Alps grew, bulldozing mountain villages. In Europe, the growing season became shorter, with spring and summers often cold and wet, triggering famines. In China, provinces that for centuries had produced bountiful citrus harvests no longer could provide them. With an additional climate-cooling blast from Mt. Tambora in Indonesia in 1815, North America and Europe experienced the year without summer in 1816.

Researchers have proposed a range of possible causes for the Little Ice Age – from decline in the sun's output, volcanic activity, some combination of the two, or some form of natural variability within the climate system. Read More