Guess where the biggest volcanic eruption of 2018 was? Hint (not Hawaii)

There have been voluminous headlines, photos, and video describing eruptions on Hawaii’s Kilaueua in 2018, and while they were visually impressive, when it comes to potentially climate altering sulfur dioxide, those eruptions pale in comparison to another Pacific volcano.

NASA Earth observatory writes:

While Kilauea dominated headlines last year, the largest explosive eruption of 2018 occurred 5,600 kilometers (3,500 miles) to the southwest on Ambae, a volcanic island in Vanuatu. The Manaro Voui volcano spewed at least 400,000 tons of sulfur dioxide into the upper troposphere and stratosphere during its most active phase in July, and a total of 600,000 tons in 2018. That was three times the amount released from all combined eruptions in 2017.

Stratospheric sulfur dioxide concentrations on July 28, 2018 Credit: OMPS Suomi-NPP

The map above shows stratospheric sulfur dioxide concentrations on July 28, 2018, as detected by the Ozone Mapping Profiler Suite (OMPS) on the Suomi-NPP satellite. The volcano on Ambae (also known as Aoba) was near the peak of its sulfur emissions at the time. For perspective, emissions from Hawaii’s Kilauea and the Sierra Negra volcano in the Galapagos are shown on the same day. The plot below shows the July-August spike in emissions from Ambae.

SO2 data from July 10 – August 31, 2018

“With the Kilauea and Galapagos volcanoes, you had continuous emissions of sulfur dioxide over time, but Ambae was more explosive,” said Simon Carn, professor of volcanology at Michigan Tech. “There was a giant pulse in late July, and then it dispersed.”

During a series of eruptions at Ambae in 2018, volcanic ash blackened the sky, buried crops, and destroyed homes. Acid rain turned the rainwater—the island’s main source of drinking water—cloudy and “metallic, like sour lemon juice,” said New Zealand volcanologist Brad Scott. Over the course of the year, the island’s population of 11,000 was forced to evacuate several times.

The OMPS instruments on the Suomi-NPP and NOAA-20 satellites contain downward-looking sensors, which can map volcanic clouds and measure sulfur dioxide (SO2) emissions by observing reflected ultraviolet light. SO2 and other gases (such as ozone) each have a spectral absorption signature, or unique fingerprint, that OMPS can measure and quantify.

“Once we know the SO2 amount, we put it on a map and monitor where that cloud moves,” said Nickolay Krotkov, a atmospheric scientist at NASA’s Goddard Space Flight Center. The maps, which are produced within three hours of a satellite overpass, are used by volcanic ash advisory centers to predict the movement of volcanic clouds and to reroute aircraft, if necessary.

Ambae eruption, July 27, 2018

Download Hi-res JPEG

At the peak of the Ambae eruption, a powerful burst of energy pushed gas and ash into the upper troposphere and stratosphere. The natural-color image above was acquired on July 27, 2018, by the the Visible Infrared Imaging Radiometer Suite (VIIRS) on Suomi NPP.

SO2 is short lived in the atmosphere, but once it penetrates the stratosphere, it can combine with water vapor to make sulfuric acid aerosols. Such particles can last much longer—weeks, months or even years—depending on the altitude and latitude of injection, Carn said.

In extreme cases, like the 1991 eruption of Mount Pinatubo, the tiny aerosol particles can scatter so much sunlight that they cool Earth’s surface below. “We think to have a measurable climate impact, the eruption needs to produce 5 to 10 million tons of SO2,” Carn said. The Ambae eruption was too small to cause such cooling.

“This wasn’t huge, it wasn’t Pinatubo,” Carn said. “But it was the biggest one of the year.”

NASA Earth Observatory images by Lauren Dauphin, using OMPS data from the Goddard Earth Sciences Data and Information Services Center (GES DISC), sulfur dioxide mass data courtesy of Simon Carn, and VIIRS data from the Suomi National Polar-orbiting Partnership. Story by Jenny Marder.

61 thoughts on “Guess where the biggest volcanic eruption of 2018 was? Hint (not Hawaii)

  1. This is perfectly illustrative of how the media is selective about what they want in the news and how they want to drive particular news stories and avoid others. In 2014 CNN spent an enormous amount of time, week after week after week, speculating about the Malaysian plane that went missing and fabricating a mountain of news. They consider themselves as one of the leaders in news media but from this an many other examples, including climate matters, they are far more deserving of the title “leaders in fake news.”

    • Hawaii made news because a) it USA , b) there was lots of expensive real estate in the potential lava flows. The news coverage was not because of potential climate impact.

      I would imagine for a US network, loss of US real estate is an important factor in news coverage choices. Not wanting to defend CNN, but that is a pretty lame attempt at attacking them when there is plenty of good reasons to do that.

      SO2 is short lived in the atmosphere, but once it penetrates the stratosphere, it can combine with water vapor to make sulfuric acid aerosols. Such particles can last much longer—weeks, months or even years—depending on the altitude and latitude of injection, Carn said.

      Here I proposed an analytic function to fit to optical depth following a major eruption. It is based on the chemistry concept of rate reaction, where reaction rates are determined by the concentration of reagents. It fits Mt Pinatubo record much better in terms of form than the usual simple exponential decay , and has its base in physical reaction rates.

      λ1λ2 / ( λ1 – λ2 ) . ( exp-λ1t – exp-λ2t )

  2. This is just a dumb speculation and maybe I’m not the first to suggest this. Every few years the water in the Pacific warms up and we get an El Nino which alters the world’s weather patterns. Is it possible that what is warming the Pacific is a surge in volcanic activity at the underwater thermal vents and/or underwater volcanic activity? I don’t know how much heat a large volcano puts out but it must be enormous and that heat has to go somewhere. Hot water would rise to the surface since it is less dense than cooler water and then spread out. Maybe it heats the surface water and that heat then causes an El Nino? Just a speculation.

    • I had numerous discussions as me too was thinking underwater volcano activity of Pacific ocean may have an impact on water temperature, but each time was told it was insignificant and the hot water do not even reach the surface. Would be nice if anyone could provide study on the subject.

      • Though volcanoes look impressive, they are drops in the thermic ocean. Nothing compared to the solar energy hitting right across the Pacific every day, or even to changes that could happen to that daily input.

      • I agree. We have no idea how much heat (or CO2) enters the oceans from undersea geologic sources. Until someone collects sufficient empirical data and properly evaluates it, it’s a valid question. But my guess is that the volcanoes we see are just pimples on the ass of an elephant.

      • Geothermal heat is probably quite important as a driver of the thermohaline circulation, but the effects of changes of that would be very long term, on the order of millenia.

    • Just two other quick thoughts on the speculation that the source of the warming that causes an El Nino could be underwater volcanic activity. As the warm water rises from a an underwater volcano or an underwater volcanic vent there would be almost no mixing of the rising column of hot water with the surrounding cold ocean water. When the warm water reaches the surface of the ocean and spreads out it would form a thermocline between the warm surface layer and the lower cold ocean water and that layering could cause the warm surface layer to persist for a long time. If this is what is happening (1) because the warm surface water is volcanic in origin it ought to be higher in minerals than the water underneath it. And (2) you should be able to forecast an El Nino by measuring underwater volcanic activity.

      Please understand I mean this only as speculation. I don’t know enough about this stuff to be serious.

      • This should be a fairly straight forward calc. – at least back-of-the-envelope calc. which I have not performed. Maybe someone can provide the calc. or someone who has an answer that studies heat movement in the ocean.
        From Windows on the Universe, here’s a quote about ocean water temp:

        “90 % of the total volume of ocean is found below the thermocline in the deep ocean. The deep ocean is not well mixed. The deep ocean is made up of horizontal layers of equal density. Much of this deep ocean water is between 0-3 degrees Celsius (32-37.5 degrees Fahrenheit)! It’s really, really cold down there!”

    • The Earth has some 65,000 km of crustal rifts, most of which are found in oceans. Furthermore, nobody has ever counted the number of (submarine) volcanoes and black smoker vents along these rifts. But that’s okay, according to the new logic, which states that if you can’t see something, it doesn’t exist. For anyone who has ever been underground in a deep mine (I have been only 4,500 ft below surface) there is the experience of the effects of the geothermic gradient of about 1ºC per 25 to 90 vertical metres. And we are being led to believe that not one joule of terrestrial geothermal energy escapes either into the overlying ocean or atmosphere.

      • not one joule of terrestrial geothermal energy escapes either into the overlying ocean or atmosphere.
        For each joule that escapes from below, there are 5555 joules incoming from above…

        • Maybe you could explain or link to the logic behind that figure, rather than simple assertion.

          Nullius in verba.

        • Is your point that any geothermal heat is overwhelmed by solar? Hard to tell from a bold assertion with so many 5s. Is that also true on a cloudy day in winter?

          Maybe so, but I know that in areas with thick-enough winter snow cover a zone above freezing develops between the snow/ice layer and soil and a significant part of the carbon cycle can occur there during the winter, and in the spring the ground thaws from the bottom up. That would seem to be mostly geothermal. So even if most of the joules are coming from the sky, it makes sense to pay some attention to those generated below. Probably not a lot when it comes to ocean temperature, although I do wonder if it may influence currents.

          • Is your point that any geothermal heat is overwhelmed by solar? Hard to tell from a bold assertion with so many 5s. Is that also true on a cloudy day in winter?
            Absolutely YES to both. Except at the poles where overwhelming heat comes from the near surface layers. Geothermal heat is inconsequential.

          • It just occurred to me that although the heat received by the ocean’s surface from the sun is so high, why is the bottom of the ocean so cold? Heat is continuously flowing from the hot mantel outwards, so also to the bottom of the ocean. Is the bottom of the ocean so cold since its almost ice cold waters come from the polar region and the speed of the ocean currents, although slow, is still overwhelmingly fast in comparison to the small heat transfer through the crust? My guess is that the answer is yes, since the bottom of the oceans are in fact so cold, and close to the maximum density of water.

          • “It just occurred to me that although the heat received by the ocean’s surface from the sun is so high, why is the bottom of the ocean so cold? ”

            Because the deep ocean water is the heaviest (=densest) available. This is either Antartic Bottom Water or North Atlantic Deep Water, very cold, salty and well-oxygenated. This sinks because it is dense. This circulates slowly at depth and ultimately is warmed a lttle bit by heat leaking down from above or up from the bottom and upwells as cold, nutrient-rich and oygen-poor waters e. g. off Peru or in parts of the North Pacific.

            This started about 35 million years ago as Antarctica was isolated and froze permanently, and was a vital part of the change from a hothouse to an icehouse climate, and it will continue until Antarctica moves away from the pole.

        • One way to estimate the heat flux from radioactive decay is to measure the neutrino flux from the decay. Half of the flux is from such decay, while the other half is left over from the formation of the earth.:
          Gando, A., Y. Gando, K. Ichimura, H. Ikeda, K. Inoue, et al. : Nature Geosci., 4, 647–651, 2011,
          DOI: 10.1038/ngeo1205.
          We do not need to know anything about the sea floor.

    • Most of the oceans, even around the equator, are near freezing temperatures at depth.
      The oceans are like a hot fudge sundae – a very thin layer of warmth covering a very cold mass.

      I would love to know the true average temperature of the world’s oceans…..not average sea surface temp but overall average by volume. That bit of info might surprise a lot of people and help them understand why the oceans can safely absorb most increases in atmospheric heat for eons.

    • It seems as though we have covered this multiple times on WUWT in the past, but the only thing I could find through a quick search is a thread post I made about five years ago…

      Kevin Kilty May 4, 2014 at 7:48 pm
      Someone above stated an estimate for heat flow in some part of the Pacific seafloor as “…it is some 300 mW/m² at the Western margin…”. Sounds about right considering world heat flow average is something like 60mW/m². It is of the same order of magnitude as tidal dissipation. Compare this to the estimate of 2,300mW/m² for the anthropogenic contribution from greenhouse gases, or the 1,000,000 mW/m² for direct overhead sunlight, and one can see that this is a very small heating source except in extraordinary circumstances. On the other hand, the acid rich water from these vents has a lot to do with maintaining ocean pH, as in its absence river waters would eventually make the oceans quite alkaline.

      While the volcanic activity along the spreading centers seems spectacular, the heat input to the world’s oceans is small on a per unit of mass basis. I’ll continue to see if I can find more.

    • Marty

      Geothermal power is in the global average less than 1 Watt/m^2. That is about 0,4 % of what we get from the Sun.

    • My problem is that on the list are 3 within 80 miles and a 4th at merely VEI6 was only 1900 years ago. Considering that the average time between eruptions is 1000 years it is a little too local.

    • During the Archean (>2.5Bya), a type of volcanism (lava known as komatiite, ultra- high in Mg with low silica and alumina) from the deep mantle was >500C hotter than todays basalts and the flows even melted channels into existing granite rocks. It was quote toasty in those days.

      Geothermal today is minor compared to the sun’s warming in tropical areas. However, locally on subduction zones along the western margins of the Americas and volcanic activity in and offshore West Antarctica and recently discovered offshore eastern Greenland (northern extemsion of the Mid-Atlantic Ridge) there is thought (not by alarmists) that warming locally likely contributes to ice melt. About 3yrs ago, a seismic survey in West Antarctica detected an active volcano erupting beneath the ice sheet.

  3. I think that we , the Western World, should considers moving the measuring of CO2 from the Pacific locations to the Island of Tasmania , South of Mainland Australia.

    No volcanos and a stretch of thousands of miles or kilometre of Ocean to its West. Nice clean air to measure . The mountains of Tasmania are a perfect site for a measuring station.. .


    • There is already an atmospheric research station at Cape Grim in NW Tasmania.
      Wonder why they don’t use the CO2 data from that as the world standard.

    • In fact, if you stand on a mountain in Tasmania, you can “see” all the way to South America as its latitude is below Africa.

  4. ‘The plot below shows the July-August spike in emissions from Ambae.’ Only about a month then back to normal. interesting.

  5. The best way to compare this eruption with those we experienced in April 1982 (El Chichon) and in June 1991 (Pinatubo) is to have a look at UAH’s lower stratosphere record (*):

    The peaks occured in September 1982 and in October 1991, respectively. This is a lag of about 4-5 months wrt the eruption times.

    Please compare these peaks with the period around November 2018.

    (*) Source:

  6. I couldn’t tell by looking on the map or article provided where this island was located. I thought it was in Indonesia. But looking it up on google earth it is actuality 1700 miles (2735 kilometers) directly east of northern Australia, and approx 2400 (3862 kilometers) miles north of New Zealand. It just wasn’t clear in my head, but now it is.

  7. Re. the “JOB” in Tasmania, no thank you. Its to cold and as I have spent too many years n warm countries, India, Burma, Egypt and Papua New Guinea, in my twilight years I like a little warmth. True right now in South Australia ti its a bit too warm, H.


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