The Gentle Giant of Africa

Mawenzi and Kibo mountains of the Kilimanjaro range. Photograph by David Daniel Turner, used under Wikimedia Commons.

Unless you are more interested in volcanoes than is technically healthy, it is likely that you have missed out a lot on the classic Monty Python skit ‘The twin peaks of Kilimanjaro’. Most people laugh at it since they believe that there is only one peak, but for us with an un-checked interest in volcanoes, we know that there are three peaks at Kilimanjaro.

It is actually even more complicated than that. Kilimanjaro is a mountain chain, and not a single mountain. Time to take a look at the individual mountains at bit closer, a lot closer in fact.



Probably the least interesting spot on Kilimanjaro, the Ururu Peak. Photograph by Chris 73, used under Wikimedia Commons.

The volcanic mountain of Shira is 2.5 million years old. It is normally said that Kilimanjaro is a stratovolcano, but Shira is more related to shield-volcanism than stratovolcanism. The last major basaltic phase was 1.9 million years ago, with minor more silicic activity continuing for another 200 000 years.

It has a large flat plateau at the top believed to be an infilled caldera, not uncommon for large basaltic shield volcanoes. Erosion had set in prior to the formation of the caldera, so it is likely that it formed due to shrinkage in a large shallow magma chamber as the magma cooled down and solidified.

Shira is slightly taller than 3 800 metres with the peak being a doleritic extrusion at 4 005 metres in the middle of the caldera that could be the remnant of the last silicic eruption. It is believed that the volcano was 1 200 metres higher prior to caldera formation, but a more reasonable height curve for a basic volcanic shield would imply 4 500 metres as the peak height.

Today Shira is the carcass of times past, and it is completely dead as volcanoes go.



Life is better with elephants infront of a large volcano. Photograph by Amoghavarsha JS, used under Wikimedia Commons.

The 5 149 metres high Mawenzi came into existence after a 700 000-year long period without volcanism. 1 million years ago eruptions started, and this time it was more silicic products that came out from the start, and a classic stratovolcano was constructed.

Today the volcano is heavily weathered with an exposed intense dyke swarm and exposed internal ring faults. The original peak has been worn down and horse-shoe shaped caldera-like structure has formed, but not through volcanic activity.

The youngest volcanic rock seems to indicate that the volcano stopped erupting 448 000 years ago.



The best picture of the intra-caldera crater. Notice that even during the more glaciated colder period of 1929 the crater was hot enough to vanquish the glacier, and there is even fumarole steam being emitted. Aearial photograph by Walter Mittelholzer taken in 1929, courtesy of ETH Bibliothek.

Kibo is what most people associate with being Kilimanjaro. The last reliable height measurement put it at 5 899 metres in 2014. But this is a variable and not a constant. I will be getting back to that below.

The top has a 2.5 by 3.5-kilometre small caldera with an intra-caldera cone present. The actual peak is named Uhuru Peak and is on the caldera wall. Inside of the caldera is a fresh-looking low cone with a pristine looking crater that is kept ice free from intense geothermal activity.

Kibo is at best lightly weathered, and to some extent almost pristine, and that is problematic. Even highly problematic, and here is why. The youngest rocks at Kibo are K-Ar dated to be 170 000 years old. And that is odd for a volcano that has been subject to a long-time exposure to weather, wind and glacial erosion.

And Kibo is quite tall enough to have been constantly eroded by glaciers throughout the last glacial period throughout to this day. In fact, it is only in the last couple of decades that the glaciers have diminished to make it relatively simple to climb the mountain. Simple being quite up to your stamina and the weather.

The ash-layered Big Gletcher Glacier. Notice the bands of ash. Most are obviously from Ol Doinyo Lengai, but one of the lower ones might be from the Lake Chala eruption. Photograph by ProfessorX, used under Wikimedia Commons.

On top of that, few stratovolcanoes can go without erupting for 170 000 years and still have geothermal fields powerful enough to overcome glacial build up inside a crater.

I will return to this oddity below.

The official word is that after activity waned at the summit caldera, a chain of more than 250 parasitic cones formed on the northeast and southwest flanks, this indicates that the entire volcano is formed on top of a NE/SW trending fissure swarm.

The fissure swarm is quite sizeable, reaching to the northeast all the way to the Lengurumani Plain, and to the southwest to Lake Chala and Taweta.

The fissure swarm cones are according to conventional wisdom 200 000 to 150 000 years old. But it is at the boarder between Kenya and Tanzania that things take a turn toward being a Monty Python skit on its own.

Lake Chala is stated as being a crater lake on a 150 000-year-old monogenetic parasitic cone. If true it is both remarkably large with a surface area varying between 4.2 and 4.5 square kilometres depending on the season.

It is also known for its happy tourist eating Nile-crocodiles. The Kenyan police calls it “Heavily crocodile infested” and recommend tourists to not offer themselves as a late-night snack. Something that tourists tend to do anyways.

Problem seems to be the monogenetic part. Locals usually try to point out to any volcanologist that ambles by that it erupted 200 years ago, and that a village containing 2 000 people was wiped out in that eruption.

A couple of decades ago a volcanologist did indeed amble out there, looked at the typical Tanzanian greenery and said, I do not see it, and wrote it off. Same with a couple of itinerant archaeologists that could not find the village.

Just to drop dead gorgeous to not insert. Photograph by Esculapio, used under Wikimedia Commons.

Problem here is that volcanologists are not particularly familiar with green things, so they believe that volcanic residue will be pristine at a lowland lake, after all it would be that in Iceland. And the archaeologists are familiar with green things, but not heavy ash layers covering a village (unless it is called Pompeii). If both had been there at the same time the result might have been different.

Understandably the locals are quite miffed at this. A couple of friends from the area in unusually strong tones explained that they would be happy to take me to the place of the former village and dig up samples for me as I happened to utter the conventional wisdom.

I plan to take them up on their offer since I am quite convinced that since everyone from the area states the same thing, something rather momentous has happened. It will also give me an opportunity to sit in the middle of the jungle imbibing the brilliant local booze called Konyagi while dodging galumphing crocodiles.


Many age-related problems

The Lake Chala crater-lake. Photograph by Joachim Huber, used under Wikimedia Commons.

The disparity between the pristine summit and the dating must be solved. I think that the problem is that the samples taken has missed the younger eruptions due to the ashes having been carried away by glacial ice movement.

Anything that lands on a mountain top glacier tends to end up quite a bit further down the sides. There is though a spot where there should be young ashes and lavas, and that is at the bottom of the crater in the middle of the caldera.

A few years ago, I would have gone up myself and taken a sample at the bottom of the crater but having become fat and old prohibits this. I would honestly need two years of exercise before even attempting that feet. It is driving me bonkers that I am no longer fit and able to run up a mountain any longer.

Thankfully I know an irritatingly fit mountain climber named Paul Schreilechtner who is going to climb Kibo during the Christmas period. He has promised to grab samples for me after I explained the problem, if the weather and conditions permit. I will then hand them over in turn for laboratory testing.

Above I mentioned that the current height is 5 899 metres, but that has changed even during the time of accurate GPS-measurements. And quite a bit to boot.

In 1999 the height was 5 892 metres, it then increased over the next 9 years to 5 902 metres in 2008, before dropping 3 metres in the next six years. Since all of these measurements are accurate to within a few centimetres something must be afoot.

This is where Kibo solidly ends up as a dormant volcano, and not even that dormant, since this means that magma is intruding at depth before it moves out (probably into the fissure swarms).

What I have written above is to be seen as an “ahem”, and not as a statement that all that is known is wrong. Instead I am stating that we need new samples from the top that is from the sweet spot, and that someone should get off their lazy arse and go and dig at Lake Chala (me).

The game is afoot!


96 thoughts on “The Gentle Giant of Africa

  1. And obviously I will go majestically off topic due to news today.
    I am obviously talking about the fifth force of nature.
    In true fashion of scientists they quickly gave it the grand name of X17 (groan).

    Now, over to you Albert since you are the better physicist. Could you expound a bit more?

    • Apparently they gave it another name, The Photophobic Force.
      I thought that was me dodging cameras, but alas…

    • I could but the journalists wouldn’t like it. This team has made this claim before and no other team could reproduce it. Now they are doing the same experiment on another reaction. A healthy dose of scepticism is recommended. Extraordinary claims need extraordinary evidence. They don’t have that.

  2. No mention of Mt Meru, and its cratered National Park, all but a fissure’s length from Kili. A massive gash in the side of Meru, suggests an event of some note. This area through to Ngorongoro is a volcanic theme park, but a bit of a wild ride in places.

    • I omitted that since I am returning to it later.
      Same for Alberts Chyulu Hills.

      And I hope that come spring we will have reasons to return at least once to Kilimanjaro as I get the samples, and if my work permits I will swing by the lake to do some digging.

      • Look at a map of Kenya, and it gives the impression that Kilimanjaro and Mount Kenya are just outliers, with the source of the heat being located just west of Nairobi where the peak of the Kenyan bulge is. Magma is pushed sideways by the bulge and ens up feeding these strange volcanoes.

        • There is also a number of outliers even further away from the rift, Chyulu Hills, Nyambeni Hills, Huri and Marsabit, unlike Mt Kenya and Kilimanjaro these are broad shield volcanoes but seem related to them somehow.

          • I limited this to the actual mountain chain of Kilimanjaro. The outliers are volcanoes in their own right as far as I know.
            I am also limiting things here to Tanzania, and leaving Kenya out of it.
            The reason for this is that I go a lot to Tanzania, but do not have Kenya on my Itinerary.

  3. Chyulu Hills is not that far and is known to have erupted within the past few hundred years.

  4. Hi Carl…
    Yes the inner Ashpit of Kibo looks extremely young
    Hot sulfur fumaroles and no erosion at all ..
    Last eruption coud have happened just a few 100 years ago?

  5. A notice on Lake Chala in the Article
    Dont swim there …. 😂

    ”An 18 year old British woman was killed in 2002 by a relatively small Nile crocodile while swimming at night in the lake.[11][12] A few days later, the Kenya Police Service said that the lake was “infested” with crocodiles while the Kenya Wildlife Service said, “Crocodiles are found in Lake Chala and it is not regarded as safe to swim at all.”[13

  6. The silent continent (at least to me)…. Thanks Carl.
    Meanwhile cracker-di-crack..

    Credits IMO

    • In the south easter rim of Barda and surprisingly shallow this time.

  7. Thanks Carl for another exciting story. Kilimanjaro looks enormous on maps and photos. Must be a considerable mass for the crust to cary. Likely it bulges down a lot. Probably it causes strain around it. Is that why the Chyulu hills are there?

    • Wouldn’t surprise me if that’s where old HPL got the name

  8. Magmas at Kilimanjaro are phonolite, phonotephrite, and tephriphonolite, the difference is between the last two, they are both intermediate compositions between phonolite and tephrite, but tephriphonolite is closer to phonolite than phonotephrite. Phonotephrite is less alkali content (7-12%) and less silica (45-53%) than tephriphonolite (9-14% alkali and – 58 to 67 % sillica ).

    These are extremely alkaline evolved sillica rich rocks… they are extremely rare too on Earths surface.
    Can I get some samples from Kilmanjaro?

    The parent magma of Kilimanjaro coud be a Basanite or Nephelinite or Tephrite that evolves into sillica rich phonolites, phonotephrites, and tephriphonolites

    • Kilimanjaro is not like other volcanoes, it is counted as one of the hardest non-Himalayan climbs on the planet. Paul is an experienced alpine mountaineer, and still it is not sure that he will succeed with the climb.
      If all goes well, he will bring down a kg of samples. The reason for the small amount is the weight of all other equipment he will need to pull off the feat of going into the crater. Most people just climb Uhuru Peak and then go home.
      To pull this off he will first climb Uhuru, then scale the caldera wall, climb the cone, scale the crater, pick sample, climb crater wall, scale cone, climb caldera wall, climb Uhuru again, then scale Kibo.
      There is a good reason that nobody as far as I know have taken good samples from the crater bottom.

      This means that after laboratory tests, and electron-microscope pictures have been taken, I will be happy if I have a sliver of a sample left myself.

      I am fully aware that getting a sample might need a series of skilled mountaineers attempting the feet. So, sorry, it is rather unlikely that you will get a sample Jesper.

      • The samples is to determine when the last eruption of Kibo was?

        • No – when the next one will be. Or at least, that is the million dollar question

        • Albert is joking a bit. Yes, I want to retest a good sample to see when the last eruption was.

          In regards of the next time it will erupt, if ever.
          We do know that it is inflating and deflating over time.
          If the original height of 5852 meters that the English got in the fifties is even close, then it has inflated almost a meter per year.
          We also know that the caldera on top is quite hot just a couple of metres down. So, I think it will erupt again at the summit, but I am not going to guess about when. It will probably not be in my lifetime.

          • Kibo and the inner ashpit looks extremely Young
            Samples needs to be collected from the inner summit crater
            Last eruption coud been only a few 100 years ago?

      • I know several people who have done the Kilimanjaro climb, always in groups. One were uni students and the other middle aged men. The really notable thing was that it was the fittest and strongest that were unable to complete it (along with the fat and really unfit) and out of those that did succeed there didn’t seem to be any way to predict it. I think its the effect of sudden loss of air pressure on this particularly grueling climb.

        PS 10 years later, strangely even those that failed seemed to have pictures of themselves on the rim. Perhaps its the trying that counts.

        • My father (who is, I’m afraid, now terminally ill) has told me that in his younger days he made the summits of both Kenya and Kilimanjaro.This would have been around the late 50s or early 60s.

          I’m aware that most of the time he spent in the African bush country was in the company of a geologist. Perhaps I should ask him more about this.

          He has also been talking about getting his old photo collection uploaded to a digital platform. Maybe he has some photos ?
          I’ll find out.

          • I am sorry to hear about your father. Old photos can be helpful. I was wondering about the raised rim around the crater. That should be more fragile than the crater itself. Did it change at all over 50 years? But your father is more important than the mountain!

          • Thanks Albert.
            He is 82 years old, so we knew it was going to come at some point.
            But as a (very highly qualified ) psychoanalyst he is calm, pain-free, lucid, philosophical,and very keen to leave no unfinished business in whatever time he has remaining.

            He is also very much a committed academic and keen amateur astronomer. His cancer was in fact discovered when he sought treatment for an injury sustained when loading his home made 15 inch reflector into his also home made mobile observatory (a converted trailer ).

            As such, I’m quite sure that if anything he had by way of either photos or just simple recollections could be of any help or interest to those with an interest in natural sciences, he would be delighted.

            I hope to see him again on either Wednesday or Thursday of this week and I’ll talk to him about it.

    • Compositon wise Kilimanjaro is very similar to Mount Erebus in Antartica, specialy the older rocks of Erebus

  9. Thank you Carl, a good read. I think I said before I have utterly no idea about African volcanoes so this place is as good as any to learn!

    • What a dream hike!

      A friend of mine did it earlier this year.
      Its a massive mountain!
      The glacier is also pretty sizeable.

      Climbing down the crater seems really hardcore stuff. Its very steep, unstable sharp terrain, hot, and to top it up, you are doing this at a very high altitude, after a very long hike up.

      I really understand why nearly everyone just gets to the top and back down.
      That’s fairly non technical. But even just that requires one to be an experienced hiker and in very good shape.

      I shall do it one day… because one remembers mountains, not days in office!

      I did once Oraefajkull. It tooks us 16 hours up and down. Because its on a ice cap.
      Kilimanjaro is about 2.5 times higher and without much ice. But a fantastic ascent from the jungles to nearly 6000m.

      • When you do, please go for the goodies inside the crater. In case my friend does not succeed.

        • It sound gruesome to reach down to the crater, I feel it will be above my abilities. If this was at 2000 meters above sea level, it would already be a difficult hike in unstable sharp and steep terrain. At 5500 meter altitude, its Russian roulette, to see who falls into altitude sickness. Maybe your friend will succeed!

          • I wonder what is the air like in the crater. Is it possible it is degassing or is it way too cold to do so?

          • The climb down to the crater floor at such an altitude looks really intimidating !

    • The details in this video is amazing… and yes the inner ashpit looks extremely young.
      Looks like it was erupted yesterday acually

  10. I just thought….If you describe Kilimanjaro as a kind of overgrown fissure row turned volcanic mountain, could it be compared with Hekla, which seems to have similar origin?

    • I would say that the comparison fails quite a bit.
      Hekla is a fissure in and of itself, and Kilimanjaro is more on a couple of converging faults (which is quite common among volcanoes).

      Kilimanjaro would be more like Grimsvötn or Bardarbunga as an Icelandic comparison. Mostly erupting from the main vents in the caldera, but at times producing a chain of monogenetic cones downrange of the fissure swarms.

      • What Hekla does in the opening stage is to open a 7km long and 10-50 metres wide vent. And at the same time it is able to deliver the opening eruption with tremendous force even though the vent is giinormously large in surface area compared to pretty much any volcano on the planet.
        Just imagine the force it takes to chuck a lavabomb 32km away, out of such a wide barrel.

        • Composition wise Kilimanjaro is an Alien compared to Iceland!
          They are so diffirent in magmas that it coud be light-years apart!

          Maybe in Snæfellsnes – Penninsula its possible to find alkaline rocks
          Where partial melting is small and deep down

          • Hekla is alkaline??
            Remeber partial melting in most of Iceland is very large…
            That should only produce Classic
            Thoelitic Basalt as base primary melt.

            And normal Andesites, Dacites and Ryholites if the basalt evolve.

            More than 90% of Icelands huge Igenous mass is Thoelitic Basalt.
            All signs that Iceland is a really powerful plume

          • Snæfellsnes – Penninsula its possible to find alkaline rocks
            Where partial melting is small and deep down…

            Near Icelands hotspot its mostly Thoelitic Basalts and their evolved equlanents because of large ammounts of partial melting in Vatnajökull and the Dead Zone

        • I tell you more Carl.

          In 1510, Hekla managed to kill someone 50km located away from the volcano (near the village of Reykholt). Imagine that!!

          10km is relatively routine shooting range for Hekla.
          32km is doable in certain larger eruptions.
          50km was achieved in 1510.
          Imagine what Hekla did in 1104 or in Hekla 3 eruption? 70km away?

          I tell you this: Near Hengill, I once found a deposit of ash layer and 3cm white pumice, dated around 3000-5000 BC, that most likely was from Hekla 3 (tje white pumice is unmistakably from Hekla in south Iceland).

          Some pieces in that deposit were 5cm.
          That was 70km away….
          I didn’t bother to explore the deposit. Maybe larger lava bombs are buried there.

          Those Hekla 3 deposits are found all across southwest Iceland.

  11. Could there be some magmatic movement at Dreki/Askja after all this tectonic cracking?

    • My amateur eyes see tectonic only. Those quakes have not been checked yet, but most of them at this spot were at 4, 5, 6 km depth.

      As far as I have read, Askja has two magma chambers at about 3 and 12 km depth. Only few deep earthquakes in past weeks has been measured by the stations and poor quality too.

      The fairly unusual spots near just east of Askja and the most northwestern tip of the Herdubreid swarm (compared to past years activity) does make me look at the nearby GPS stations more often. There are minor changes in movement, but my amateur eyes cannot reveal any trend. It is fun to draw gps – movement arrows on a map to get the big picture and see how directions change a bit in time.

      Ha, we are heading to a new eruption… But when will that be! 😬🙄

      • Most likely you are right. My suspicion was the events from 1842 that lasted 5 minutes or so.
        Deep not checked yet..

  12. I remember eating breakfast before going to work and on some mornings on a clear day you could see the peak of Kilimanjaro. I was living in Wongonyi, Kenya. Happy days.

  13. Just a random thought – could the volcanic range Kilimanjaro sits on that heads eastward from the primary African rift be a result of a rotational kind of force going on?

    IE, if the craton and block shearing away from Africa is moving away from the primary African continent faster than it is to the south, there would also be some tearing action going on here. This would come as the craton would likely see some pivoting-type of force at some point.We can obviously see that the rifting is more prominent the closer you get to the Afar region (in the north) so this could make at least some practical sense of why places like Kilimanjaro exist in the first place.

    • The African continent will split in the weaker younger seams between the cratons.

      In the far future
      When the Superplume head move closer to the surface there will be massive ammounts of partial melting: and production of huge ammounts of mainly Thoelitic Basalt.
      Africa is the next continental LIP?

      For now the spreading have not come to that point yet.
      Tanzania and Kenya areras are extremely thick crusted and ”hard” so magma production is lower and more alkaline there today

    • ” the craton would likely see some pivoting-type of force at some point”

      You would likely need a GPS survey to determine that, sort of like they did in Oregon-Washington state. The problem is that it’s not the safest region and like some other countries, the gear may have a tendency to walk off.

      • I wonder if they could redesign the gear to be hidden or miniaturized, I know gps units can be very small nowadays, no bigger than a postage stamp

    • You freaked me out for moment. I read “Alabama” at first. As far as I know, 4.8 is about the strongest to ever occur near my area.

    • been a few biggish quakes around there in the past few days – and greece, and turkey, presumably all tectonic, but still rather unpleasant to live through – all the best to those affected

  14. Carl Rehnberg – Two volcanologists skilled at climbing volcanoes.

    You probably need to be a Python aficionado to understand that.

    • Do you think they cloned the software?

      There has always been a suspicion about Dolly. Since you can’t tell sheep apart anyway, what is the point of cloning them?

      • I wonder what the price of the software is. It claims to be cost-effective, so I guess it’s sheep.

  15. RE: Kilimanjaro sample:
    I wonder if a Fed-Ex Drone could do a “pick-up”?
    Could design one like the Curiosity Rover sky-crane. Drop a machine to do some excavating, then come back later to retrieve machine + samples.
    Only problem is there may not be enough air to support a drone at that altitude….unless it had a helium balloon to add buoyancy?

  16. A Kilimanjaro eruption can be both effusive and explosive. The tephriphonolite – Phonolite magmas are very viscous so if gas rich you gets a pyroclastic explosion. The Kibo outer caldera is probaly result of a large VEI 5 or small VEI 6 event.

    The inner Ashpit is probaly result of very mild vulcanian activity with repeated domes thats been blasted away.

    If gas poor you gets blocky lava flows and domes
    That seems to be the main features of Kilimanjaros summit cone. Kilimanjaro formed through many blocky flows.
    The flanks may erupt much more fluid Basanites and Nephelinites forming the flank cinder cones

  17. Albert.
    I saw my father this evening. He said that it was around 1956 that he climbed Kilimanjaro, and he certainly saw the crater. No photos I’m afraid. He also said that whilst he remembers being there, he should really say that he can’t help either way because firstly, a lot of time has passed since then. Secondly, he has seen countless photos and videos of the mountain since then. Given his particular field of expertise, he knows very well the limitations of memory, so he cannot give us anything useful.
    That’s a pity, but I think he’s being entirely realistic.

  18. Offtopic. Always pleasant to wake up to a government wake up phone call that there is a flood alert to my local area and house. Interestingly enough, Extinction Rebellion was organizing a local protest precisely to alert for sea level rise. A strange coincidence. I went to see the ocean and it was unusually high. As our house sits at 2 meters above sea level, this makes you think about 1) what will happen in the next few hours, and 2) long-term future planning, where to relocate.I can’t stop thinking how much will all these coastal houses and properties devalue in the following decades, after decades of speculation and price increase.

    Now, there is one country, where I lived already, which seems to be heading towards a bright future considering all these things, and that is Iceland. The country naturally rises faster above the ocean than the ocean can rise (not only due to isostatic uplift but actually due to the uplifting caused the Icelandic plume). In addition, weather wise, its climate will become much milder and it has endless stores of free energy, plus already has built large amounts of food greenhouses. The sad side is that its growing population will naturally damage the pristine environment, which is already being damaged by explosive tourism in recent years. Will Iceland become a kind of Indonesia (crowded volcanic country) a century from now?

    • Carbon dioxide from human industrial and daily activities are enormous.
      At current pace and future if nothing is done,
      Human CO2 emissions will turn earth into Eocene Supergreenhouse in just 120 to 150 years in Co2 levels. We humans relase 200 times more co2 of all the worlds 1500 active volcanoes combined!.

      Because of our CO2 emissions
      Iceland will be in the middle 2100 s a Subtropical paradise like Azores or Northen New Zeeland thats clogged with humans.
      The whole Reykjanes Penninsula is urbanized.
      Iceland will become forested too: probaly with laurel forests and other human invasive plants.
      Iceland will become a northen New Zeeland climatewise and tourism-wise.

      Vatnajökull icesheet dissapearing vanishment
      Will cause large ammounts of partial decompression melting over the Iceland Plume and a probaly a few Lakis or a Thjorsahraun and many shields

      • I think a significant loss of social order will have happened by then to be honest. With the world population where it is a significant breakdown in epidemic control would stop society in weeks as food and energy supplies cease to function. A world of a few hundred million is easily sustainable at the basic level.

        • I don’t understand that line of thought, ‘it would breakdown in weeks? ‘

          Wouldn’t it take years for the problems to manifest themselves so in essence it would be regulated by scale?

          • Generally things tend to overshoot and overcorrect. Current developed world society, particularly in europe, would rapidly fail if, for example searching for limited food supplies or hiding from an epidemic, resulted in failures of electricity supplies/gas/fuel etc. Its a positive feedback where the more people look out for themselves and stop working (food, fuel, heat) the more the entire system breaks down. In the case of an ebola-style global epidemic just about everything would fail more-or-less simultaneously.

            I am quite sure western governments are aware of this.

        • Iceland already has a rapid growing population, as well as places like Scotland, so the trend is going to be there, with population also rapidly growing in Greenland and parts of Canada and Russia. Wait and see.

          However do not underestimate the human impulse for survival. I think one thing is going to happen:
          – Temperature reaches around 2C by 2035, the world is experience even larger extremes and the governments in desperation resort to geoengineering by sulfur spraying. Its going to be very controversial and certainly I do not support it. (I support a dramatic reduction in CO2 emissions by reducing our energy needs and discontinuing coal stations)

          I say one example: Trump. The guy portrays himself as a climate denialist (and I dislike him), but he is not a climate denialist, he knows very well what is happening. Trump quietly has been supporting sulfur spraying geoengineering as a cheap effective dirty tech fix.

          As an amateur astronomer an stargazer, this is a worst case scenario: hazy skies for decades in a row, whilst the world tries to capture carbon, and the ozone layer thins and acid rain returns. And the possibility of a few wars in Asia due to changes in the monsoon caused by the spraying, and violent protests across the world against geoengineering.

          Its going to be an hectic century.

          Lithium wars for instance. Water wars. Another big unknown: China, which plays also a big role as possibly the world largest economy and carbon contributor. They are really the big unknown factor. What are they trying to do? One thing is sure, they are a totally controlled society. I hope that their model is not exported worldwide, because it seems we have been plagued by more authoritarian governments in recent years across the entire world.

          AI is another wild card. With AI and growing tech, things would become quite unpredictable, both the potential for massive solutions and massive new unforeseeable problems.

          • However my reasoning above is highly simplified and based in several assumptions. It does not include for instance grey or black swans events. So there is a distinct probability that I am acutely wrong.

            What could some grey or black swan events be?
            – A massive VEI8 volcanic eruption (very unlikely) or a plague like in 1348 or 1918 (significantly more likely) or even an economic crash (even more likely!!) significantly halts our carbon emissions or even our solutions and damages the current fabric of society, making all my predictions off track.
            – Alien contact. This would be a massive game changer. All our assumption about aliens are also potentially wrong, so I cannot say what kind of impact they would have. I also cannot refuse the possibility that they there aren’t already here and already having a hidden impact. Maybe aliens like a warmer world and they are just waiting for our demise, lol!
            – Another grey swan: I die before the mid century, and because I am not here, nothing of this matters at all!
            – There are probably more black swan events that I can’t think of.

      • An urbanized Reykjanes Peninsula? Bad idea! This is a volcanically active zone, even if there hasn’t been a subaerial eruption for centuries. Not to mention the sea level rise.

        • Yup thats true and its in a way already urbanized
          Reykjavik haves many pahoehoe flows from middle ages in its outskirts

          The lava threat to Reykjavik certainly exist.
          An option coud be to expand the city in the Snaefellsness Penninsula direction, where chance of lava invasion is lower.

        • Reykjanes is still poorly urbanized.

          I lived in Iceland for 5 years. There is only Reykjavik in one side, Keflavik, a small village in the other side (with the airport). And a few smaller lovely villages in the south coast and also some industry across the north side of the peninsula too, where the airport highway is located.

          Still plenty of desert and lava fields around. Feels still very wild and remote in the middle of the peninsula.

          But it will change quite rapidly in upcoming decades.

      • Jesper, one more thing. At the current rate, and Icelandic university research, Vatrnajokull will disappear within 200 years. By 2100, having only about two thirds or half of the size.

        Its not difficult to calculate this.
        Vatnajokull melts on average 2 meters per year. But in recent years, it has melt considerably more than that in some places.
        It has an average thickness of perhaps 400 meters (but in places more than 1km)
        This gives an average estimated expiry date of 200 years for Vatnajokull.

        Way before that, Langjokull will disappear (within this century). It is a massive ice cap too, with two large central volcanoes. Its already experiencing quick retreat in some parts.

        Then you have Hofsjokull. Another massive large volcano.
        Decompression will affect all of them.
        Something similar like 10000 years ago, when all the non-glaciated parts of Iceland suddently melted, and then Iceland experience large eruptions in many of its volcanoes.

        • Grimsvötn will become very happy when the enormous glacial load is removed
          Probaly producing something twice the size of Laki a few 100 years after the ice vanishes. ( decompression melting )

          Its already now capable of enormous basaltic eruptions as 1996 and 2011 showed.
          2011 was specialy hot and primitive

  19. Hi Albert
    I summited Mauna Kea last year above 4100 m.
    No problem at all ( did not felt the lower oxygen )

    If I was suddenly placed at Kilimanjaros summit ( 6000 m ) woud I suffer from the thinner atmosphere?
    2000 m higher than the peak I summited last time..

    Or woud I feel nothing?
    I have read at above 4000 m most persons thats not acclimatized really starts to feel it

    • Hi Jesper,
      Depends…. how long you stay there, what you are doing there, what your phyisical shape is. When you stay longer than a day, the chance suffering of Acute Mountain Sickness is fair. But not everyones body can’t cope.

      In my finer days I hiked in three days starting at 1800 m to 4400m (up down, up down, up …), rested one day and tried to reach a pass at 5400. I couldn’t get there, went back at 4900. The path was easy but headache and nausea made me turn around.

      • I haven’t done this yet. Despite my love of mountains, my highest altitude has been only 3600m in the Alps, I felt the lower oxygen, but could still hike, albeit slower.

        I heard that altitude sickness differs and cannot be predicted. Even people with great physical shape can be severely affected, whilst others could be just fine.

        Adaptation, hike high, sleep low, is often the key.

        I think everyone feels the effects at nearly 6000m of Kilimanjaro.

  20. Over the past few years I have seen more and more Portuguese research news that there is indeed a subduction region being in the early stages of its formation off the coast of Portugal, namely to the its southwest.

    This is where a “minor” M7.8 earthquake and small tsunami happened off the coast of Portugal.
    And where probably the first 1755 earthquake event started.

    Scientists have discovered final proof that pieces of the crust are moving some 250km deep under that spot, located southwest off the coast of Portugal.

    So its official, the Atlantic is subducting off the southwest coast of Europe.

    • Looks violent! But explain to me why this is different from the other intermittent big EQ’s in BB?

      • It’s nothing really too different just it’s been so quiet there for so long and now it just got loud, continued recovery under BB

        This is interesting, vertical displacement from 2004 to 2016

        • There is a second aspect to this: glacial melting. The glaciers push Iceland down, and as they are melting Iceland shows some resurgence. Part of this signal is global warming!

  21. So i stay away from the computer (phone) a few days and Carl gives us a text on my favourite area, African rift
    Thanks Carl, now my ‘fomo’ is really increased.

Comments are closed.