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| The volcano exploding in Tonga last weekend. Its effects were felt around the world, but the eruption is unlikely to cause any noticeable global cooling. |
When I first posted about this volcano, I wondered if the ash and sulfur and stuff that billowed all the way up into the stratosphere would have an effect on global climate. Large quantities of sulfur injected into the stratosphere would tend to temporarily cool the Earth's climate.
The huge eruption of the Pinatubo volcano in the Philippines back in 1991 pushed enough sulfur into the stratosphere to cool the world by about a degree Fahrenheit for a year or two. An even bigger volcanic eruption in 1815 cooled the world even more dramatically, with cold and disastrous results.
According to the Washington Post, satellite data analyzed over the weekend suggest the Tonga eruption had only about 1/50th of the impact of Pinatubo, which means Saturday's blast would only cool the world, or counteract continued global warming, but 0.02 degrees Fahrenheit. In other words, basically too small to notice.
That said, if the Tonga volcano keeps erupting, it could belch more and more sulfur into the stratosphere to the point where it could have a noticeable, though temporary effect on climate.
ATMOSPHERIC/OCEANIC REVERBERATIONS
Even so, that Tonga blast was mighty. One estimate is the blast had 14,000 times the yield of the atomic bomb that destroyed Hiroshima. So of course the Tonga last was felt one way or another around the world. First, let's go to the source, right at the blast site. Volcanic eruptions often produce lightning, but Tonga was off the charts. Lighting detection equipment detected 60,000 strikes or 70 lighting strikes per second in the first 15 minutes following the blast, says the Washington Post.
I was stunned yesterday to read the volcanic blast was heard 1,500 miles away in New Zealand. It turns out, the shock wave generated a booming noise in Alaska, 5,000 miles away from the volcano. Hawaii is closer to the volcano and nobody reported noise there, so there must have been some sort of weather situation in Alaska that made it audible.
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| Climatologist Brian McNoldy (@BMcNoldy) posted this graph showing five atmospheric pressure jiggles from Tonga volcano shock waves passing over Miami. The lowest one on the bottom, labeled in yellow, was not a volcano shock wave but rather a strong cold front passing through. Click on the image to make it bigger and easier to see. |
Tsunamis from the volcano were detected pretty much all over the world. Some of them were surprisingly large. In Peru, the tsunami killed two people and caused a lot of flood damage along the coastline.
The tsunami created a four-foot spike in water levels at Port San Luis, California, 3.5 feet at Arena Cove, California, 2.7 feet at Crescent City in northern California and 2.8 feet in King Cove, Alaska, reports the Washington Post.
There are actually two types of tsunamis. The most familiar - and dangerous - ones are caused by earthquakes and volcanoes. Another type, meteo-tsunamis are triggered by abrupt changes in weather, such as a sudden air pressure rise or fall or very quick changes in wind speed or direction.
The Tongo volcano produced both types of tsunamis all the way over in the Caribbean Sea, though anyone standing on a beach there probably wouldn't have noticed. But instruments did detect the tsunamis.
About 24 hours after the volcanic explosion, the tsunami directly caused by the event had rounded the base of South America, and spread out in a subtle fashion across the Atlantic Ocean into the Caribbean.
In Martinique, the tsunami amounted to about a 0.2 meter, or nearly eight inch shift in water levels. But half a day before that the water levels at Martinique beaches wiggled much more modestly. That was caused by air pressure changes created by the shock wave in the air created by the volcano.
The atmospheric shock wave circled the globe more than once. It went all directions of course. The eastbound one crossed the United States and was measurable across the nation, reaching us here in Vermont at around 11 a.m. Saturday.
The westbound edge of the shockwave crossed Asia, Europe and the Atlantic Ocean, reaching us here in New England late Saturday night. Then it continued westward across the nation again.
For some reason, the air pressure changes with that second one were a little bigger than the earlier one in Vermont/New England, despite having traveled a much larger distance. I'm not sure why, and I haven't found any credible source that would explain why.
One guess is that the shock wave had traveled all the way across the Atlantic and was not disrupted by mountains and other terrain. Or, the air over us late Saturday was especially cold and dense, which could have left the atmosphere more prone the disturbance caused by the shock wave.
In Miami, sensitive barometers have recorded air pressure jiggles five times as the remains of those shock waves orbit the Earth.
In one instance, in Seattle, the atmospheric perturbations probably briefly changed the weather. A thin temperature inversion had the Sea-Tac airport fogged in. When the shock wave arrived, the fog cleared briefly, apparently because the pressure change disrupted the temperature inversion. Once the shock wave passed and the barometric pressure stabilized, the fog came back.
TONGA ITSELF
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| An island in Tongo covered in ash from the massive volcanic eruption last week. Photo by Vanessa Parker/AP |
As NBC News reports, international phone lines and the internet are still down in the region, so it's hard to get a grasp of what's going on along Tonga's chain of islands.
We do know at least three people died in the large tsunamis that swept Tonga, in addition to the two who died in the smaller tsunami in Peru. Thick ash turned the normally verdant landscape brown. Scores of buildings along the coasts have been swept away. A reconnaissance flight over one island showed a collection of about 50 houses had been entirely swept away.
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