How do volcanoes affect the climate?

Question

How do volcanoes affect the climate?

Answer 1

volcanoes can affect the climate in many ways. one the ash from a volcano canblock the sun, making cold weather. which scientist think killed the dinosaurs.

Answer 2

This is a question that a lot of people are trying to figure out. There are two things to think about. The first is how the area very near to an erupting volcano is having its weather affected. The second is how large eruptions will affect the weather/climate around the world. I think more people are worried about the second issue than the first.

As far as I know, the main effect on weather right near a volcano is that there is often a lot of rain, lightning, and thunder during an eruption. This is because all the ash particles that are thrown up into the atmosphere are good at attracting collecting water droplets. We don't quite know how the lightning is caused but it probably involves the particles moving through the air and separating positively and negatively charged particles.

Another problem that we are having here in Hawai'i involves the formation of vog, or volcanic fog. The ongoing eruption is very quiet, with lava flowing through lava tubes and then into the ocean. Up at the vent is an almost constant plume of volcanic fume that contains a lot of sulfur dioxide. This SO2 combines with water in the atmosphere to form sulfuric acid droplets that get carried in the trade winds around to the leeward side of the big Island. The air quality there has been really poor since the eruption started in 1983 and they are getting pretty tired of it. It also seems as if the amount of rain on that side of the island has been low during the same time. You might think that with all those sulfuric acid particles floating around there would be plenty for rain drops to nucleate on but the explanation I heard was that thes droplets are all the same size and for good rain nucleii you want a variety of sizes.

As for the world-wide affects of volcanic eruptions this only happens when there are large explosive eruptions that throw material into the stratosphere. If it only gets into the troposphere it gets flushed out by rain. The effects on the climate haven't been completely figured out. It seems to depend on the size of the particles (again mostly droplets of sulfuric acid). If they are big then they let sunlight in but don't let heat radiated from the Earth's surface out, and the net result is a warmer Earth (the famous Greenhouse effect). If the particles are smaller than about 2 microns then they block some of the incoming energy from the Sun and the Earth cools off a little. That seems to have been the effect of the Pinatubo eruption where about a 1/2 degree of cooling was noticed around the world. Of course that doesn't just mean that things are cooler, but there are all kinds of effects on the wind circulation and where storms occur, and just about anything else you can think of. Some folks think that large eruptions can cause the weather phenomena called "El Nino" to start. This is a huge disruption of the Earth's atmospheric circulation. The connection hasn't been accepted by everybody though.

An even more controversial connection involves whether or not volcanic activity on the East Pacific Rise (a mid-ocean spreading center) can cause warmer water at the surface of the East Pacific, and in that way generate an El Nino. Dr. Dan Walker here at the University of Hawai'i has noticed a strong correlation between seismic activity on the East Pacific Rise (which he presumes indicates an eruption) and El Nino cycles over the past ~25 years. Lots of people seem not to like this idea, but it hasn't been disproved either.

Answer 3

For once, I must dispute the normally reliable Bob.

Volcanic dust is far more important to global climate than the CO2 emitted by eruptions (which is small in a global context). The dust from volcanic activity can and does block sunlight from reaching the earth, causing a spike of cool temperatures in the year or two following a major eruption.

Here's a more quantitative analysis.

http://arxiv.org/ftp/physics/papers/0411...

Answer 4

It can make the clouds black.And the lahar will destroy the city. The houses will destroy. Many people will die and suffer if the volcano erupts.Not only our climate will change also the city and our green living.

Answer 5

Relatively little.  Their effects are short lived, more like weather than climate.  And, in terms of temperature, there are two opposing effects.  Emissions of CO2 cause warming, and those of dust cause cooling.  They mostly cancel each other out.

Much more here:

http://www.geology.sdsu.edu/how_volcanoe...

EDIT - Keith - "Their effects are short lived, more like weather than climate."