Iceland Volcano Eruption Too Small to Have Significant Climate Effect, Science Group Says

Volcanic ash from Mt. Eyjafjallajokull in Iceland is disrupting air travel. Could it also disrupt the climate?

The short answer is yes--at least temporarily. When sulfur dioxide
from volcanic eruptions enters the second layer of the atmosphere--the
stratosphere--it converts into sulfuric acid particles that act like
tiny mirrors reflecting sunlight back into space, cooling the planet.
The Eyjafjallajokull eruption, however, is still too small to
significantly affect the climate, according to the Union of Concerned
Scientists (UCS). The amount of cooling depends on the type of material
and the amount of time it stays suspended in the atmosphere.

Eyjafjallajokull pales in comparison to past climate-cooling
volcanic eruptions. Eyjafiallajokull's ash has reached a height of
55,000 feet, according to press reports. By contrast, ash from the 1991
Mt. Pinatubo eruption,
one of the biggest in the 20th century, reached 78,740 feet. Overall,
Pinatubo, which is in the Philippines, ejected 14 to 26 million metric
tons of sulfur dioxide that produced a significant global cooling effect for a few years. Following the eruption, this temporary cooling also slowed sea level rise rates temporarily.

Even if a volcanic eruption were big enough to temporarily cool the
planet, heat-trapping carbon dioxide from burning fossil fuels and
destroying forests would still pose a significant threat, says UCS
climate scientist Brenda Ekwurzel.

"Unlike volcanic ash that will leave the atmosphere within a few
months or years, carbon dioxide remains there for decades and even
centuries," Ekwurzel said. "Overloading the atmosphere with carbon
dioxide has put us on the path toward a long-term warming trend, so we
really can't pin our hopes on occasional volcanic eruptions to solve
the problem."

The short-term cooling effects of the Mt. Pinatubo eruption are long
gone, and global warming is continuing unabated, she said. "In fact, we
just experienced the hottest decade on record."

Some scientists are exploring the possibility of mimicking volcanoes
by artificially injecting sulfur dioxide into the atmosphere to
temporarily cool the planet, which theoretically would give
industrialized countries more time to reduce their carbon dioxide
emissions. Such schemes should be viewed with caution, Ekwurzel said.

"We're already conducting a giant experiment with the planet by
injecting so much carbon dioxide into the atmosphere," she said. "It's
not clear that the potential risks of more human tampering with the
climate are worth whatever temporary relief this might provide. But the
fact that scientists are even contemplating these ideas does highlight
how urgent the need to act has become."

While a quick-fix is appealing, there are serious drawbacks to
intervening with a complex climate system. Ekwurzel points out that the
ocean is becoming more acidic as it absorbs excess carbon dioxide from
the atmosphere, threatening coral reefs and other marine life.
Deliberately reflecting sunlight would do nothing to change this and it
could have other hard-to-predict effects, such as changing rainfall
patterns.

"Climate change isn't just about the Earth's thermostat," she said,
"It's about rapidly shifting our climate in ways we might not even be
able to fully anticipate. The prudent thing to do is dramatically
reduce our emissions to avoid finding out just how bad climate change
could become."