This news is not anything new, but i remember that after this eruption of Pinatubo in the Philippines that summer ( in Oakland, California ) never really seemed to ever come into the cycle of seasonal change. And that whole year after that episode was always clouded and cooler that year. With fewer days or weeks of heat that summer season. Seems that this would be stretch and a bit premature, but have they begun the process of starving the planet with most recent eruption and perhaps more to come dare i say of this sycotic activity? And are we seeing the beginning of the coming ice age issues that have been talked about by Scott and the C's? I aim not asking just scratching the head a little.
'Sunshade' for global warming could cause drought
08:13 02 August 2007 by Catherine Brahic
Pumping sulphur particles into the atmosphere to mimic the cooling effect of a large volcanic eruption has been proposed as a last-ditch solution to combating climate change - but doing so would cause problems of its own, including potentially catastrophic drought, say researchers.
Sulphur "sunshades" are just one example of a "geo-engineering" solution to climate change. Such solutions involve artificially modifying our climate to counteract the effects of human greenhouse gas emission. Other examples include space mirrors and iron fertilisation of the ocean (see also Sunshade for the planet.
Recent research has suggested that sulphur sunshades could rapidly cool the climate back down to pre-industrial temperatures (see Solar shield could be quick fix for global warming).
However, a study, led by Ken Caldeira of the Carnegie Institution of Washington in the US, warned that failing to correctly deploy or maintain such a scheme would result in sudden warming - which would be worse than the long-term warming that had been avoided because of its swiftness.
Now, Kevin Trenberth and Aiguo Dai of the National Center for Atmospheric Research in Colorado, US, have shown that - even if correctly deployed - a sulphur sunshade could have deleterious effects on the environment by reducing rainfall.
Cooling cloud
Sulphur sunshades are inspired by the cooling effects of large volcanic eruptions, which blast sulphate particles into the stratosphere. The particles reflect part of the Sun's radiation back into space, reducing the amount of heat that reaches the Earth. In 1991, the eruption of Mount Pinatubo in the Philippines cooled Earth by a few tenths of a degree for several years.
To study the effects that sulphur sunshades might have on rainfall, Trenberth and Dai looked at trends in precipitation and continental run-off from 1950 to 2004 to try to detect the impact of the eruptions of Mount Agung in Indonesia 1963, El Chichón in Mexico in 1982, and Pinatubo in 1991.
The researchers had to account for the effects of El Niño, which tends to decrease rain over land, and increase it over the oceans. After this, a marked decrease in rainfall and run-off in the year after the Pinatubo eruption was clear (see graph, right).
However, the Agung and El Chichón eruptions did not produce a detectable signal in the precipitation records. Pinatubo is thought to have pumped significantly more particles into the atmosphere than Agung and El Chichón, releasing aerosols that increased the optical density of the atmosphere by about 10 times more than each of the other two. "We think those two were not strong enough to have an effect on precipitation," says Dai.
Dai and Trenberth say their results suggest that artificially putting large amounts of sulphate particles into the atmosphere in order to decrease solar radiation could have catastrophic effects on the planet's water cycle. "Creating a risk of widespread drought and reduced freshwater resources does not seem like an appropriate fix," they say.
They note that the negative effects experienced after Pinatubo erupted were harshest in the tropics.
Volcanoes put a lot of stuff into the stratosphere that can produce global cooling, but we don't have a lot of good observations," [Jerry Meehl] adds. "Pinatubo was a large explosion and produced a significant global climate effect, so we were able to get really good observations about what was spewed into the atmosphere. It's helped us reconstruct a history of past volcanoes that we can put into a [long-term] climate model."
Pinatubo was much different from the 1980 eruption of Mount St. Helens in Washington, which blew sideways. Its gaseous plume stayed relatively low. Pinatubo went up like a geyser.
"Pinatubo was huge," [Chip Trepte] says. "It went into both hemispheres and the debris moved over the globe very quickly. So we learned a lot about circulation patterns in the upper atmosphere. It's like putting a color dye in a sink or bathtub, so you can see how the fluid moves. Pinatubo created a laboratory for us where we could observe all these motions in the atmosphere
International Herald Tribune
05-09-2001
The sky darkened and the ground shook. It sounded like a ''stampede of 100,000 animals,'' said a Filipino who witnessed it. When Mount Pinatubo erupted 10 years ago, it spewed a column of ash 40 kilometers (25 miles) into the sky. Fist-sized rocks and sand rained down here for weeks, blanketing the area with a moon-like layer of ash that stretched for dozens of kilometers, a ''giant sand trap,'' in the words of a resident. The eruption, on June 15, 1991, was the second biggest of the 20th century, according to the U.S. Geological Survey. Nearly 1,000 people were crushed by collapsing roofs or swept away by mud slides. The …
Pinatubo Validates Climate Model
Released: 1/22/1997 12:00 AM EST
Source: Los Alamos National Laboratory
Los Alamos National Laboratory
James E. Rickman, (505)665-9203/elvis@lanl.gov
LOS ALAMOS COMPUTER MODEL ACCURATELY PREDICTS GLOBAL CLIMATE EFFECTS OF PINATUBO ERUPTION
PUERTO VALLARTA, MEXICO, Jan. 20, 1997 - The world's gotten a little colder since the 1991 eruption of Mount Pinatubo in the Philippines.
But Los Alamos National Laboratory researcher Jim Kao said the eruption has helped validate the accuracy of a Los Alamos computer model of Earth's climate.
Kao, who works in Los Alamos' Atmospheric and Climate Sciences Group, today at the International Association of Volcanology and Chemistry of the Earth's Interior 1997 General Assembly in Puerto Vallarta, Mexico, presented information about how the Pinatubo eruption has helped deplete Earth's ozone layer, increase global cooling and validate Los Alamos' three-dimensional global climate model.
When the mountain erupted for a two-month period in 1991, with a major eruption on June 15, 1991, it spewed millions of tons of sulfur compounds into the atmosphere. About a month later, the sulfate aerosols had formed a wide band around Earth's middle latitudes. This, in turn, began a cycle of damage -- a cycle different than the damage to lives and property suffered by Filipinos who felt the mountain's fury firsthand.
"Sulfate aerosols play a very important role in the chemical reactions that help deplete Earth's ozone layer," Kao said. "In aerosol form, the sulfur dioxide mixes with water vapor and forms sulfuric acid, an important catalyst in ozone depletion reactions. Not only that, but when we get ozone depletion, we get a little bit of a cooling effect because ozone normally acts as a greenhouse gas by trapping heat from surface-emitted terrestrial radiation; it also absorbs direct sunlight. In addition, ozone depletion reactions involving sulfate aerosols work better at lower temperatures. So we can guess that volcanic eruptions might play an important role in ozone depletion worldwide."
To test the hypothesis, Kao and colleagues Xuepeng Zhao and Richard P. Turco of the University of California, Los Angeles, and Los Alamos collaborator Scott Elliott used the Los Alamos global climate model to show what effects the Mount Pinatubo eruption might have had on Earth's global climate.
The model predicted that the amount of sulfate aerosols released by the eruption was ideal to promote sustained ozone depletion reactions.
The model predicted that Earth's ozone layer would deplete by about 12 percent during the winter of 1992 and 1993. Satellite data collected that winter indicated that the ozone levels had depleted by about 15 percent.
But more than that, the Los Alamos global climate model predicted that a wind vortex encircling the Arctic -- which traps and segregates ozone and ozone-destructive chemicals during the winter months and gives rise to an uninterrupted period of ozone depletion -- would remain for a longer period than normal after the eruption.
During the winter, less sunlight reaches the pole and the area becomes cooler. Prevailing westward winds begin to circle the pole until a vortex surrounds a center of calm -- where ozone and the ozone-depleting chemicals can interact undisturbed. When the region warms during spring months, the vortex breaks, and the trapped air mass begins mixing with mid-latitude air masses.
"Since there was a depletion of ozone levels during the winter of 1992-93, and since ozone is a greenhouse gas that absorbs heat, we would expect to see the polar vortex last longer because the area inside the vortex would remain colder longer," Kao said. "During the winter of 1992-93, as the model predicted, we didn't see the polar vortex break until two weeks later than normal." Kao and his colleagues will adjust the model to account for actual observed ozone levels, atmospheric circulation and heating patterns, and chemical reaction rates.
"The ultimate goal is to develop a very accurate three- dimensional model including comprehensive chemistry that will help us understand the intricacies of the global climate," said Kao. "Fortunately, we had something as unfortunate as the 1991 eruption of Mount Pinatubo that we could use as a way to test and validate our model."
Funding for the global climate model and Kao and his colleagues' research comes in part from Los Alamos' Institute for Geophysics and Planetary Physics.
Los Alamos National Laboratory is operated by the University of California for the U.S. Department of Energy. [/quote]
