Kelud and the Global Weather

The first image out of the crater of Kelud. Photograph by Suwarno.

Hello and welcome to this double-article, in it you will get two different takes on the question if Kelud really will affect the global climate by two different writers. So, let us see if we get two different answers shall we? First part is by me, and the second part is by GeoLurking.

After the fast and brutal eruption of Kelud there has been a lot of humdinging in the media about the effect on the global climate. According to some of them it seems like we are in for a new ice-age. But what is the truth?

Recapitulation of Kelud

The eruption of Kelud was one of those rare ones that Volcanic Explosivity Index –scale is perfect for. The VEI is intended to use on this kind of short and brutally explosive type of eruptions. It might also be the fastest ever eruption to yield numbers and data that we could compare to other eruptions.

Within a day we knew not only that it was a VEI-4 eruption, we also knew that it was the second largest this millennium with an erupted volume of 0.3 cubic kilometers of Dense Rock Equivalent, we knew that the ash-column reached 28.2 kilometers height and all this lovely fast data seems to have given both the Tinfoiling doomsayers and the media cramps in their abysmal tracts.

Ash as a weather altering factor

First we need to understand which volcanic factors might affect the global climate. Please remember that these interact in several ways that is not fully understood, but do not make the mistake and think that we can’t make good assumptions on what will happen to the world temperature.

First factor is the ash itself since it acts as a mirror reflecting the sun’s rays away from the earth’s atmosphere. It is affected by various factors. Among them is how coarse the ash is, the finer the ash, the longer it will float in the atmosphere. The other is ash-column height, the higher the ash gets the longer it will float. We also know that if the ash is ejected out of the troposphere into the stratosphere it will hang for a longer time. Since the stratospherial boundary is at roughly 17 kilometers height at the Philippines we know that this happened.

Now, something to remember is that the amount of ash decreases exponentially over time. This effectively means that if the amount of ash 24 hours after the eruptions end is X it will be 0.25X another 24 hours later.

So, we know that the ash from Kelud would lower global temperature. The question is just how much and for how long? We will get back to that and get a surprising answer.

Volcanic gasses

Aerosol index from Pinatubo. Wikimedia.

We know that gasses can affect the global climate. And volcanoes emit a lot of gasses as they erupt. Basically we can divide these up into 3 different groups. The first and most abundant gas from an explosive eruption is water. A volcanic eruption produces voluminous amounts of water vapor and these form clouds, and clouds shield the surface against heat so they should really lower the temperature on earth. Problem is that even a very large volcano produces small amounts of water vapor compared to what the planet produces on a daily basis. And it also has a tendency to drop down rapidly in the form of rain, normally within hours of getting cooled down into water droplets.

Next gas is Ye Olde CO2. Now most of you are going: “Wait a minute, that is a greenhouse-gas and should increase global temperature?” Well, you are right. And too really drive home this point. Volcanoes are by far the largest source of CO2.

Now we get to the sulphates and sulphuric gasses. These are actually good at shielding the planet from the sun’s rays. They have about the same half-life in the atmosphere as CO2 and here you should find the best source for global volcanic cooling. Unlike the ash it will actually stay floating in the stratosphere for quite some time.

Other large eruptions

The ash cloud from the eruption before the VEI-6 phase started. Wikimedia commons.

We have two good examples to compare Kelud to. One is the 2011 eruption of Grimsvötn since it so far is the largest eruption during this millennium.

First of all Grimsvötns eruption column was lower than Keluds. But it still managed to punch through the stratosphere boundary that is considerably lower over Iceland. Grimsvötn erupted 0.5 cubic kilometers of DRE and a likely 1 cubic kilometer of sub-aquatic lava into the ice-covered glacial lake. Grimsvötn is also famously gassy. It has less magmatic water content, but punches a much higher sulphuric gas content than Kelud.

Now, let us go to the largest eruption in the last 102 years, the Colossal VEI-6 eruption of Pinatubo. At 10 cubic kilometers of DRE and 36 kilometers high ash column together with the 17 million tons of SO2 it caused a known climatic effect that we can compare with.

Immediately after the eruption 10 percent of the suns radiation was reflected away from the surface of the planet. This in turn caused a global lowering of the temperature with 0.4 degrees Celsius. As such Pinatubo is the only volcanic eruption that we have as accurate data from in regards of climatic effects.

Conclusion

The eruption cloud of Pinatubo photographed from the STS-43 shuttle mission. Image by NASA.

Before we start any final summary we need to know that the larger VEI-4 that Grimsvötn suffered in 2011 did not affect the weather at all. You should also know that it ejected 5 to 15 times as much sulphuric agents as Kelud. This should really end any discussion, but people are often more stubborn than that. So let us put Keluds effect against Pinatubo…

Pinatubo ejected roughly 30 times as much ash into the atmosphere as Kelud, and to make it even worse it ejected the ash 28 percent higher up into the stratosphere. It also ejected 30 times as much sulphuric compounds to a 28 percent higher altitude.

In short, the effect of Pinatubo was between 30 and 100 times larger than from Kelud.

This leaves us with two answers, in a way Kelud has no climatic effect at all for either you or the researchers. But from a scientific standpoint it probably had an effect, but it will be so small that it is not even measurable. At worst we are looking at a lowered temperature of 0.013C to 0.004C, you are welcome to try to measure that.

CARL

^{Fuzzy Dice – Wikimedia Commons.}
“As I have said so many times, God doesn’t play dice with the world.” — Einstein.

As some of you know, I am a fan of Nicholas Taleb. He is the author of “The Black Swan: The Impact of the Highly Improbable” (2007). Mostly in jest, I have occasionally kicked around the idea of a ‘Black Swan Volcano,’ mainly from the point of view that in order to really ruin your day (on a humanity scale), it’s going to take more than a simple decline in solar activity to mess things up. All of the previous wild excursions in temperature, though they generally coincide with low solar activity, are punctuated by some sort of volcanic activity. The current decline in solar activity has been called out as very similar to the start of the Dalton minima and naturally, those that tend to do so, have been off beating on that drum. One can only guess at the level of noise that we would get if it were a Maunder Minimum scale event. Some solar physicists, such as Dr. Leif Svalgaard, think that the tally of sunspot activity is flawed and that the levels that denote “Grand Minima” or “Grand Maxima” are a bit skewed due to the criteria and methods that the official observers used when making the tallies. Even I.G. Usoskin (University of Oulu, Finland) has joined in on Dr. Svalgaard’s working groups that are trying to resolve those inaccuracies in order to get a research quality count. Usoskin is the primary author of “Grand minima and maxima of solar activity: New observational constraints” Usoskin et al (2007)

Okay, that’s a bit of background. You will likely get into a heated argument should you adopt the Grand Minima banner and start waving it about in peoples faces.

So, onward to that pet idea I’ve been kicking around. Unfortunate Coincidental Volcanoes popping up as ruiniers to an ordinarily pleasant climate. By Taleb’s definition of BlackSwans, you don’t see it coming. It’s buried in the statistical improbability and even if some wild arsed loon saw it coming, no one would believe them. The Stats would indicate otherwise.

Recently, Kelud exploded, and did so in style. My initial interpretation of the VAAC reports were that it didn’t make it to the tropopause. It’s a safe assumption on my part since VAAC’s are mainly interested in keeping aircraft away from the plumes. They would most likely tend to over alert. It wasn’t until a couple of days later that someone posted a satellite view of the plume along with a LIDAR trace that showed that Kelud had easily made it to the stratosphere… that LIDAR trace even seemed to show that part of it reached as high as 26 to 28 km.

No matter how you look at it, that is way up there. Okay, so maybe Kelud is in the running for the mythical Black Swan status. It really depends on how much SO2 was lofted. I don’t have a really good way to estimate that, but I can show you a few other volcanoes and let you determine what could be coming done the pike.

Nasa keeps track of the stratospheric aerosol layer for their climate models. (the veracity of those models is left up to the reader). You can find ascii text data for the volcanic forcing of those models here. Taking that, and an output of VEI 4+ eruptions, you can get a view of some of the culprits.

As you can see, the monster eruptions tend to have the most effect. But, notice how puny Novarupta is compared to Pinatubo and Krakatau. This is going to be due to where it erupted and what it erupted. At a higher latitude, Novarupta had easier access to the stratosphere, and all tropical systems tend to have a higher level of water vapor entrained into the column. (causes early leaching of SO2) This should work to Novarupta’s advantage. Yet it didn’t. Sulfur is the 16th most abundant element in Earth’s crust, being more prevalent than Chlorine (usually found in salt NaCl). As far as I know, how much sulfur was in Kelud’s column has yet to be published. But sulfur collecting is a pretty common way to augment income in some locales.

GEOLURKING

Riddles

This week there are 3 volcanoes hiding among the riddly brainwrecks, plus 1 volcanologist and 1 volcanologic word.

1. Half of Fritz and Image – Tuff (Kelda, 2pt). Robert Downey Jr (on the image) stared in the movie Tuff Turf that was directed by Fritz Kiersch.
2. Diplomatically acting a war among the stars – Sir William Hamilton (Kelda, 2pt) Hamilton was the name of an actor in the original Star Wars movie. Sir William made the first comprehensive list of Vesuvius eruptions.
3. Chained dragon and tyrant on white giant – Damavand (Dinojura44, 2pt). According to a Persian epic poem both a dragon and a tyrant have been chained inside a cave in the mountain, it is known in persion also as the White Mountain due to it always being snow-covered.
4. Depressed flaming mountain with young husband – Turpan or Turfan in China (Evan Chugg, 2pt) It sits in a depression and is known as the flaming mountain. The explorer Francis Younghusband visited the nearby city.
5. Sulphurious ohridian dwarf volcano – Duvalo in Macedonia (Alison, 2pt). At half a meter wide and 0.3 meters deep it is the worlds smallest known volcanic edifice.

Score board
18 Sissel 10 Cryphia 8 Evan Chugg 7 Dorkviking 4 Dinojura44 4 Edward	4 Kelda 4 Pyter 3 Matt 2 Inannamoon 2 Lughduniense 2 Lurking	2 Spica 2 UKViggen 1 Bobbi 1 KarenZ 1 Sa’Ke

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