Merapi--again! Disrupts Obama visit this week

A village covered with ash from an eruption on
Thursday, November 11, 2010.  Photographer unknown,
source

According to some reports, the death toll from the on-going Merapi eruptions has exceeded 200, and nearly 400,000 people have been displaced from their homes and villages. President Obama visited Indonesia earlier this week, but cut his visit short be several hours so that his plane would not be caught by changing winds.  To date, the eruptions have released about 140 million cubic meters, exceeding the 100 million cubic meters estimated to have erupted in 1872.

In a paper in press for Geophysical Research Letters (now online), Anchukaitis et al. have examined the influence of volcanic eruptions on climate, and arrive at conclusions that challenge the major results from the Global Circulation Models currently used to model climate.  Those models predict that large volcanic eruptions should result in unusually dry conditions through the regions of Asia that experience monsoons. Anchukaitis et al. used two long tree ring-based proxy's to reconstruct moisture patterns. The first was a tree-ring chronology from a long-lived ccypress species in southern Vietnam, and the second is the "Monsoon Asia Drough Atlas", which also includes tree-ring proxies.  These reconstructed conditions indicate that the response to volcanic eruptions is an anomalously wet southeast Asia and dry conditions over central Asia, a conclusion that is the exact opposite of effects predicted by three widely used climate models: CSM1.4, CCSM3, and GISS ModelE. The authors also conclude that strong El Nino and La Nina weather conditions could be important.  Anchukaitis concludes "...that some GCMs do not correctly capture the balance of important coupled ocean-atmosphere processes involved in the response of Asian climate to radiative forcing.  In a press release accompanying the article the authors also caution that the study suggests that proposed geoengineering schemes to counteract manmade climate change with huge artificial release of sulphates similar to those emitted by volcanoes might have complex unintended consequences.

As of this time, volcanologists do not think that the eruption at Merapi is big enough, or sulfurous enough, to affect the climate.