Many are asking this very question as the Mount Merapi volcano continues to spew ash along with the pyroclastic flows and mudslides (lahars). I heard on NPR this morning that the ash is so heavy, not only is it literally thickening the air being breathed, but it is clinging to the leaves and branches of trees and causing the trees to collapse. So not only is the current tree-based fruit growing season gone (among other crops), future seasons if not already ruined are in serious jeopardy. But there’s more.
A natural byproduct of volcanic eruptions is the emission of sulfur dioxide which is associated with increased occurrence of respiratory disease, difficulty in breathing and death. Experts at OSHA recommend short-term exposure at no more than 5 parts-per-million.
There’s no word yet on what sulfur dioxide level the lower-levels of the atmosphere near Mount Merapi, but the upper-levels are showing high concentrations as the included NASA “Image of the Day” shows. In the upper atmosphere, sulfur dioxide reacts with water vapor to form the beginnings of sulfuric acid (see: acid rain). These same ions can reflect sunlight. At the right latitude and altitude, and with enough concentration, a cooling climate can result. And because these ions can last for years, global climate change is possible.
So far, Mount Merapi has not released the sort of concentration that would trigger this sort of event. In fact, the released sulfur dioxide is only a small percentage of the 1991 eruption of Mount Pinatubo which, according to scientists at Michigan Technological University, had a measurable change of global climate.
YourWeatherBlog has written on the Mount Merapi volcano before. You can read more here.