April 19, 2010

Our Planet Earth is putting on quite a show in celebration of the 40th Anniversary of Earth Day! For those interested in seeing photographs, the Boston Globe.com ran a feature this weekend with twenty striking images of the volcano, including shots of people on cross country skis taking photographs at the edge of the hot lava. Talk about a study in contrasts!

 The volcano continues to erupt in Iceland,  and air travel is still disrupted in northern Europe and Great Britain. If you look at this satellite image, you can see why:



Photo: AP Photo/NEODAAS/University of Dundee


The land mass at the top/left of the photo is Iceland. The two land masses at the bottom/center of the photo are Ireland and Britain. You can see why no planes are flying out of England - the country is enveloped in volcanic ash.

This volcano has not been studied extensively, so scientists do not know how long the eruptions might continue. From what has been observed so far, there will not be a significant impact on Europe’s weather. It takes a very big volcanic event to impact weather across a continent, or across the globe. When Mount Pinatubo erupted in the Phillippines on June 15,  1991, scientists   estimated that 20-million tons of sulfur dioxide and ash particles   blasted more than 12 miles high into the atmosphere. The eruption caused widespread destruction and loss of human life. And, the gases and solids injected into the stratosphere enveloped our globe for three weeks.That volcano caused an average 10% drop in temperatures,  affecting the world’s weather that year.

The eruption of   the Tambora volcano in 1815 (in what is now Indonesia) was one of the biggest weather influencers ever, triggering the famous Year   without a Summer in 1816. 

Scientists do not agree on whether even a huge volcanic eruption (much bigger than the one we’re experiencing this week) could ever have a long-term impact on climate.

Remember, weather is different from climate. When you talk about weather, you are talking about       what is happening in the atmosphere that day in a particular location. Weather tells you whether to wear a raincoat one day, or a sleeveless shirt and shorts on another day. Climate tells you the average weather in a particular place over a period of years - for example, it’s typically hot and dry in Florida in the summer. That description of Florida’s typical climate won’t do you much good when a late afternoon thunderstorm breaks out!                   

Certainly, whenever a volcano is blasting sulfer dioxide into the air, it is increasing the amount of greenhouse gases in the air. But, it would take a much bigger volcano than this to significantly impact global warming, and to ultimately change our global climate.

As for the impact on our weather, we will have to wait and see the full extent of the Eyjafjallajökull eruption. 

As I wrote in my book, WEATHER,  we can be sure of only two things about the weather: We’re going to have it and it’s going to change.



Posted by: Seymour Simon

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