HR: 1355h
AN: V53E-02 INVITED    [Abstracts]
TI: Volcanic Eruptions and Climate: Sulfates are More Important Than Halogens in Producing Climate Change
AU: * Robock, A
EM: robock@envsci.rutgers.edu
AF: Department of Environmental Sciences, Rutgers University, 14 College Farm Road, New Brunswick, NJ 08901, United States
AB: Large volcanic eruptions inject sulfur gases into the stratosphere, which convert to sulfate aerosols with an e- folding residence time of about one year. The radiative and chemical effects of this aerosol cloud produce responses in the climate system. Using examples from major eruptions of the past and results from experiments with numerical models of the climate system, this talk illustrates the major impacts. Volcanic eruptions produce global cooling, and are an important natural cause of interdecadal and interannual climate change. One of the most interesting volcanic effects is the "winter warming" of Northern Hemisphere continents following major tropical eruptions. During the winter in the Northern Hemisphere following every large tropical eruption of the past century, surface air temperatures over North America, Europe, and East Asia were warmer than normal, while they were colder over Greenland and the Middle East. This pattern and the coincident atmospheric circulation correspond to the positive phase of the Arctic Oscillation. High latitude eruptions in the Northern Hemisphere, while also producing global cooling, do not have the same impact on atmospheric dynamics. They weaken the Indian and African summer monsoon, and the effects can be seen in past records of flow in the Nile and Niger Rivers. In fact we can use records of the Nile River flow to provide an improved date for the Eldgjá eruption in Iceland, which we now date at 939 A.D. While halogens may have short term effects on ozone in plumes with high halogen concentrations, there is no evidence that they are important in the global climate response to volcanic eruptions.
DE: 0370 Volcanic effects (8409)
DE: 1620 Climate dynamics (0429, 3309)
DE: 1626 Global climate models (3337, 4928)
DE: 8409 Atmospheric effects (0370)
DE: 8428 Explosive volcanism
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting