From Reuters: Sulfur emitted in eruptions of more than a dozen worldwide volcanoes, including Kasatochi in Alaska's far western Aleutian Islands, are part of the explanation -- about 15 percent -- for a recent slowdown in global warming, according to a study by U.S. and Canadian scientists. Big volcanic eruptions are a "wild card" in climate science because they can't be predicted, scientists say.
The pace of rising world surface temperatures has slowed since an exceptionally warm 1998, heartening those who doubt that an urgent, trillion-dollar shift to renewable energies from fossil fuels is needed to counter global warming.
... "This is a complex detective story," said Benjamin Santer of the Lawrence Livermore National Laboratory in California, lead author of the study in the journal Nature Geoscience that gives the most detailed account yet of the cooling impact of volcanoes.
"Volcanoes are part of the answer but there's no factor that is solely responsible for the hiatus," he told Reuters.