volcanic ash

Volcanoes may have greater influence on climate than previously thought

A newly published French study of last year’s eruption of the Eyjafjallajökull Volcano in Iceland suggests that models have underestimated the aerosol formation and hence cooling effect of volcanic eruptions “by 7 to 8 orders of magnitude.”

The Abstract reads:

Volcanic eruptions caused major weather and climatic changes on timescales ranging from hours to centuries in the past. Volcanic particles are injected in the atmosphere both as primary particles rapidly deposited due to their large sizes on time scales of minutes to a few weeks in the troposphere, and secondary particles mainly derived from the oxidation of sulfur dioxide. These particles are responsible for the atmospheric cooling observed at both regional and global scales following large volcanic eruptions. However, large condensational sinks due to preexisting particles within the plume, and unknown nucleation mechanisms under these circumstances make the assumption of new secondary particle formation still uncertain because the phenomenon has never been observed in a volcanic plume. In this work, we report the first observation of nucleation and new secondary particle formation events in a volcanic plume. These measurements were performed at the puy de Dôme atmospheric research station in central France during the Eyjafjallajokull volcano eruption in Spring 2010. We show that the nucleation is indeed linked to exceptionally high concentrations of sulfuric acid and present an unusual high particle formation rate. In addition we demonstrate that the binary H2SO4 – H2O nucleation scheme, as it is usually considered in modeling studies, underestimates by 7 to 8 orders of magnitude the observed particle formation rate and, therefore, should not be applied in tropospheric conditions. These results may help to revisit all past simulations of the impact of volcanic eruptions on climate.

Besides primary ash, the researchers say that sulfur dioxide, which oxidizes to sulfuric acid, can act as cloud-forming nuclei that can change the precipitation over a region. The clouds would also partially reflect solar irradiance and therefore contribute to cooling.

UPDATE: New NASA paper says volcanoes primarily responsible for increased SO2:

Recently, the trend, based on ground-based lidar measurements, has been tentatively attributed to an increase of SO(2) entering the stratosphere associated with coal burning in Southeast Asia. However, we demonstrate with these satellite measurements that the observed trend is mainly driven by a series of moderate but increasingly intense volcanic eruptions primarily at tropical latitudes.

See also:

Iceland volcano and its effect on life Photos

Icelandic Volcanoes Geologic Setting

Katla volcano in Iceland may be priming to erupt

Yellowstone Super Volcano

Carbon Dioxide and the Greenhouse Effect

Some Effects of Volcanic Ash Eruptions

Yesterday I wrote about the geologic setting of the Iceland volcanic eruptions. Fellow blogger Carolyn Classen asked about “vog” the volcanic smog caused by Hawaiian volcanic eruptions.

There is a variety of opinion on the health effects of the volcanic ash. Close to the eruption site, there is a danger from volcanic gases (such as carbon dioxide, fluorine, and sulfur dioxide) to both humans and livestock. In some Hawaiian eruptions the sulfur dioxide produces smog and acid rain. Acid rain can cause crop damage. And from living in Douglas, AZ, when the copper smelter was active, I know that sulfur dioxide really cleans out your sinuses. But for ash dispersed farther away, Britain’s Health Protection Agency said the concentration of ash particles that may reach the ground “is likely to be low and should not cause serious harm.”

According to the U.S. Geological Survey vog (volcanic smog) is a mixture that includes gases but is predominately aerosols (tiny particles and droplets) formed when volcanic gas reacts with moisture, oxygen, and sunlight. It is this unique mixture of gas and aerosols that makes vog both difficult to study and potentially more harmful than either gases or particles alone. What we have learned from limited studies about the aerosols that comprise vog is that most of the aerosols are acidic and are of a size that is readily retained by the lung. Also, studies done in urban areas having similar pollutants show that these types of aerosols degrade lung function and can compromise our immune system. These effects are especially pronounced for children, individuals who have chronic asthma or other respiratory impairments, or those with circulatory problems. Remember, though, that these are studies of mainland urban areas that have similar pollutants, not studies of vog itself.

According to the International Volcanic Health Hazard Network, in most eruptions, volcanic ash causes very few health problems. In fact, officials there say, there is “almost no risk to people” from this particular ash eruption.

Any effects people do feel are likely to be minor. People may experience itchy or irritated eyes, a runny nose, sore throat or dry cough, or they may notice the smell of sulphur or see a dusty haze, the British Health Protection Agency said. Eyes can become painful, itchy, or bloodshot or produce a sticky discharge, and gritty pieces can scratch the cornea, causing abrasions or a non-contagious form of pinkeye. Skin irritation is less common, but if the ash is acidic, skin could redden and become irritated

But those with pre-existing respiratory problems could experience bronchitis or asthma-type symptoms like wheezing and shortness of breath because fine ash particles can irritate airways, causing them to compress, or they can cause the lining to make more secretions inducing coughing and heavy breathing. Livestock and pets may also be affected.

A study of the Soufrière Hills stratovolcano on the Caribbean island of Montserrat which has been erupting since 1995 says that long-term exposure to high levels of volcanic ash could lead to silicosis. (See: http://tinyurl.com/y262a28 )

The ash may be good for the oceans. According to several studies (noted by Scripps Institution of Oceanography) the initial dissolution of volcanic ash in seawater provides an external nutrient source for primary production in ocean surface waters that may stimulate biological drawdown of CO2. Volcanic ash releases large amounts of phosphate, iron, and other “macronutrients and ‘bioactive’ trace metals. These same nutrients produce fertile soils on land.

The ash poses danger to aircraft engines and some instruments such as pitot tubes (for gauging air speed). The danger could last for months. “The problem with the ash is that it’s difficult to detect except in large concentrations, but we don’t know how low a concentration is ‘safe,’ so flight traffic controllers have to err on the side of caution,” said Jonathan Fink, an ASU professor and volcanologist whose specialty is studying volcanoes and their aftermath. “The major danger occurs when ash gets sucked into the engines, melts into glass and then that glass fuses to the engine parts. The ash also damages windows and windscreens, making it hard for pilots to see. Ash has not caused any commercial airliner to crash yet, but it’s come very close.”

The haze of suspended ash will produce beautiful sunsets.