Thursday, April 23, 2015

Will That Huge Chilean Volcano Cool The World? (Spoiler: Probably Not Much)

Just after the start of yesterday's Calbuco
Volcano eruption in Chile.  
I'm sure I'm not the only person who has been absolutely fascinated by the beautiful but deadly images of the Calbuco Volcano that erupted unexpectedly in Chile yesterday.

A huge plume of ash towered several miles into the clear Chilean sky, mushrooming outward as it went high in the atmosphere in kind of an End Times tableau.

I've splashed some images of the Calbuco Volcano eruption throughout this post.

The immediate worry is, of course, the people who live nearby. The eruption came as a surprise to everyone, including scientists watching the volcano, so evacuations were hasty and chaotic.

I haven't heard of any deaths yet, which is a good thing.

Huge volcanic eruptions can disrupt the global climate, though my early reading is this eruption of Calbuco won't affect things too much.

As you can tell by any photo you've seen of Calbuco, volcanoes can emit an enormous amount of ash. The ash shades local areas, but quickly falls out of the sky, so the ash itself has little if any effect on the global climate.
The ash cloud spreads out over the
erupting Calbuco Volcano in Chile.  

Volcanos can also release a large amount of sulfer dioxide, which, if the volcanic eruption is big, can get pushed into the upper atmosphere and change the climate temporarily.

If the volcanic eruption is strong enough to push sulfer dioxide all the way up into the stratosphere, the sulfer dioxide turns into sulfer aerosols.

Each molecule of these aerosols acts as a little mirror, reflecting sunlight away from the Earth and thereby cooling the climate.

There have been a number of volcanic eruptions lately, and that might have shaped a marginal, pretty much unnoticeable bit of warmth from the climate that we otherwise would have seen.

The volcano keeps erupting as the sun sets.  
Still, 2014 was the warmest on record for the entire globe, and 2015 is off to its hottest start on record, if you consider the entire Earth, so volcanic eruptions clearly haven't had a noticeable effect.

However, yesterday's Calbuco eruption was particularly large. I haven't seen any analysis from scientists on how high in the atmosphere any sulfer dioxide got, whether any got all the way up into the stratosphere, and if so, how much.

My impression is, while big, Calbuco wasn't the kind of huge eruptions that would have a significant effect on global climate. I'll be interested to see what the scientists say about this in the coming days and weeks.

We have one relatively recent example of a large volcanic eruption having a subtle but noticeable effect on the climate. Mount Pinatubo in the Philippines erupted in 1991.  It was the second largest volcanic eruption in the world for the 20th century and sent sulfer as high as 21 miles into the atmosphere.

Enough sulfer aerosols got into the stratosphere that we could all notice a haze high up in the sky, and global temperatures cooled by about a half a degree for a couple years. That doesn't sound like much, but it temporarily reversed most of the effects of human caused global warming up until that time.

And it was noticeable. The summer of 1992 was the third coolest and third wettest on record in the United States.

At, the volcano emits a bright orange glow, and
lots of lightning in the volatile ash cloud.  
The sulfer aerosols from volcanic eruptions falls out of the atmosphere after a couple of years, and global temperature trends fell back into their previous pattern by 1993 or 1994.

Volcanic eruptions have, in history, been much bigger thatn Pinatubo and had much more serious effects on the global climate.

Ancient volcanoes have caused mass global extinctions. In more modern times, a volcano called Tambora in Indonesia had enormous global impacts when it erupted in April, 1815.

According to the Economist:

" sent molten rock more than 40 kilometers into the sky in the most powerful eruption of the past 500 years. The umbrella of ash spread out over a million square kilometers, in its shadow day was as night. 

Billions of dust, gas, rock and ash scoured the mountain's flanks in pyroclastic flows, hitting the surrounding sea hard enough to set off deadly tsunamis; the wave that hit eastern Java, 500 kilometers away, two hours later, was still two meters high when it did so. The dying mountain's roar was heard 2,000 kilometers away."

Worse, the immense amount of sulfur aerosols sent into the stratosphere cooled the global climate for a couple years to sometimes deadly effect.

In New England and parts of the Midwest, the eruption was the main cause behind the "Year Without a Summer" in 1816. Snow drifted up to 20 inches deep in Danville, Vermont in June. Frosts hit every months of the year - including July and August - across much of New England and the upper Midwest, destroying harvests.

Harvests failed in the cold in Europe, too. Grain was in short supply in Britain. Glaciers surged down Alpine Valleys. In China thousands starved due to poor harvests and cold, said the Economist.

Again, I don't know what effect yesterday's Chilean eruption will have, if any, but it certainly will not do anything close to what Tambora did in 1815.

That volcanoes can cool the world with sulfer aerosols has gotten people thinking this could be a neat way to combat global warming.

After Mount Pinatubo erupted in 1991, a scientist named Ken Caldeira began to wonder if constantly injecting sulfer aerosols into the stratosphere would combat global warming.

He didn't think that idea would amount to much, but his studies showed that the idea would indeed work.

However, it's not something Caldeira recommends, says Grist.

He contributed to a National Academy of Sciences report that, according to Grist, "concluded that technologies to block solar radiation should not be deployed at this time; and warned, 'There is significant potential for unanticipated, unmanageable, and regrettable consequences in multiple human dimensions....including political, social, legal, economic and ethical dimensions."

So nope, we're not going to act like volcanoes and inject stuff into the atmosphere like a bunch of volcanoes.

Instead, we'll stand in awe of eruptions like Calbuco, and hope that nothing like Tambora happens again.

Here's a video, including some time lapses, of the Calbuco eruption:

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