November 2017 – Cabot Institute for the Environment blog

New research by Cabot Institute members reveals super eruptions more frequent than previously thought

Posted on November 30, 2017April 5, 2023 by janet.crompton

Toba supervolcano – image credit NASA METI AIST Japan Space Systems, and U.S. Japan ASTER Science Team

I’m sat in my office in the Earth Sciences department reading a research paper entitled ‘The global magnitude-frequency relationship for large explosive volcanic eruptions’. Two lines in and I can already picture the headlines: ‘APOCOLYPTIC VOLCANIC ERUPTION DUE ANY DAY’ or perhaps ‘MANAGED TO GET OFF BALI? YOU’RE STILL NOT SAFE FROM THE VOLCANOES. The temptation is to laugh but I suppose it’s not actually very funny.

The paper in question, produced by four Bristol scientists and published in Earth and Planetary Science Letters on Wednesday, uses a database of recorded volcanic eruptions to make estimates about the timing of large world-changing eruptions. It is the first estimate of its kind to use such a comprehensive database and the results are a little surprising.

In case you’re in a rush, the key take-home message is this…

When it comes to rare volcanic eruptions, the past is the key to the future. Volcanoes have erupted in the past. A lot. These past eruptions establish a pattern, which, assuming nothing has changed, can give us clues about the future. This can be done for a range of eruption sizes, but this paper focusses on the biggest of the lot. It turns out they have happened more frequently than previously thought. Yes, it’s surprising. No, you don’t need to worry.

Here’s how they did it:

In reality, supplying the kind of information needed for a study like this is an enormous task. Generations of volcanologists have found evidence of volcanic material from thousands of past eruptions scattered all over the world. Key bits of information on these eruptions has been collected across many years by hundreds of geologists and collated in one place called the LaMEVE database.

The database essentially turns each volcanic eruption into a statistic based on when it erupted and the eruption size. These statistics are the fuel for the study by statistician Prof Jonty Rougier and three volcanologists (and Cabot Institute members), Prof. Steve Sparks, Prof. Katharine Cashman and Dr Sarah Brown.

The paper highlights that overwhelming majority of these eruptions have been fairly small (think Eyjafjallajökull*, think Stromboli), a smaller proportion have been a bit more lively (heard of Krakatau? Mount St. Helens?) and a really very tiny proportion are so big they might be described as ‘civilisation ending’ if they occurred today. I can’t give a well-known example of one of these as we, fairly obviously, haven’t had one in human timescales.

Mount St Helens. Credit: Keri McNamara.

To give you a flavour, here are some statistics from the Toba super-eruption that occurred about 75 thousand years ago. The eruption produced a minimum of 2800km³of material.^.That is equivalent to covering the entire area of the UK in a 12-meter-thick layer of volcanic material, or filling the O2 arena a million times. It is thought the corresponding ash and aerosols that circled the earth cooled the surface temperature by between 3 and 10^oC. The reduction in the sun’s radiation would see the death of the majority of plant species, and consequently human’s primary food source.

It paints a rather grim picture. The alarming part of the new study is that eruptions such as Toba might not be as rare as previously thought. Earlier reports have suggested that these eruptions occur every 45-714 thousand years. The new paper revises this range down to 5.2 -48 thousand years with a best guess of one every 17 thousand years. According to geological records, the most recent super eruptions were between 20 and 30 thousand years ago (Taupo 25 ka, Aira 27 ka).

Given that humans started to use agriculture around 12 thousand years ago, it seems as though our modern civilization has flourished in the gap between super eruptions. As Prof.Rougier commented: “on balance, we have been slightly lucky not to experience any super-eruptions in the last 20 thousand years.” A little scary perhaps?

Here’s why you shouldn’t worry:

The really important part of all this is uncertainty.There is a huge amount of statistical leeway either side of these estimates.
Trying to put an exact number on the recurrence interval of something so naturally complex is a bit like trying to estimate the final score of a football match without knowing exactly who the players are. You know how well the team has performed in the past, but you don’t know who will play in the future, or if the same player will behave the same way in every game. There are
also a whole range of things that could happen but probably won’t – perhaps the whole match will get rained off?

Volcanoes aren’t much different. Just because a volcano has exhibited one pattern in the past, doesn’t necessarily mean it will do the same in the future. Volcanic systems are infinitely complicated and affected by a huge range of different variables. Assuming perfect cyclicity in eruption recurrence intervals just isn’t realistic. As Prof. Rougier said ‘It is important to appreciate that the absence of super-eruptions in the last 20 ,000 years does not imply that one is overdue. Nature is not that regular.’

On top of that, our records of volcanic eruptions in the past are far from perfect. Sizes of prehistoric eruptions are easily under or overestimated, and some are simply missing from the record. Generally, the further you go back in time, the hazier it gets. While Rougier and his co-authors have done their best to account for these uncertainties, it is impossible to do so completely.

If that wasn’t enough to put your mind at rest, it is important to remember that geological timescales are a lot bigger than human ones. Whether a volcano erupts every 200 thousand years or 202 thousand years is a very small difference in the context of a volcano’s period of dormancy.
But the extra few thousand years encompasses the last two millennia and the
hundreds of human generations that have lived within it.

When it comes down to it, the real risks from volcanoes come not from the super-eruptions, but from the smaller, frequent, more locally devastating eruptions. Ultimately, when volcanoes like Agung in Bali erupt, it isn’t us who will suffer. It is those who depend on the volcano for their homes and livelihood who will have to uproot and leave. The real value in this research is not in scare mongering, or in a dramatic headline, it’s developing new techniques that further our understanding of these unpredictable natural phenomena.

(*Remember
in 2010 when a volcano in Iceland erupted and shut European airspace?
Eyjafjallajökull: Pronounced ‘eye-ya–fiyat-la-yer–kitle’ in case anyone’s interested)

Read the original press release Time between world-changing volcanic super-eruptions less than previously thought

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This blog is written by Keri McNamara: Cabot Institute writer and geologist in the School of Earth Sciences at the University of Bristol. Keri’s current research looks at using ash layers to improve records of volcanism in the central Main Ethiopian Rift.

Keri McNamara

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My Reflections on COP23 – challenges, inspiration, and hopes for the future

Posted on November 22, 2017April 5, 2023 by janet.crompton

I had the great pleasure of attending COP21 in Paris, 2015. The air was full of anticipation, hope and a clear sense of urgency. The achievements of the conference were remarkable and as a climate scientist I felt a degree of reassurance (albeit uneasy reassurance) that there was now a serious global commitment that may lead to a turning point in climate action.

Two years on, I was therefore excited to attend COP23 in Bonn as part of the IPCC (Intergovernmental Panel on Climate Change) delegation, to see how things were progressing.

I was immediately struck by the difference. The negotiations here were largely focussed on how to implement the Paris Agreement. The discussion were necessarily more technical, but less awe-inspiring, ‘nuts and bolts’. Without the big deadline and the huge public pressure to sign a global agreement, it seems things in the negotiations moved slowly, and there was an air of frustration amongst some negotiators and campaigners.

Despite the slow pace in the negotiations, this blog shares some real highlights from the week, as well as some low lights, alongside my thoughts on proceedings.

Last one out

COP23 started with an announcement from Syria that they would sign the Paris Agreement, leaving the USA isolated as the only country that will not be part of the Agreement – Trump’s announcement to withdraw from the Agreement offers a stark reminder of the impact of domestic political change on international initiatives.

The #wearestillin campaign has caught
the imagination of businesses and civil
society alike.

It was however encouraging to go to the launch of the US #wearestillin campaign – a collection of states, cities, businesses, NGOs, civil society etc that are willing to make a commitment to climate change despite Trump pulling out of the Paris Agreement. With Bloomberg having offered to cover for the USA’s climate finance and on our side of the pond, Macron offering to cover their commitments to the IPCC (with a little top up also from the UK government).

Despite anticipating that the US delegation might join Saudia Arabia and others to stall progress, they sent the usual negotiators who were being helpful in the side-lines, if quiet during decisions. China, on the other hand, were not being as constructive as they could have…..

Climate finance, historical responsibilities and ability to pay.

Finance is always one of the biggest sticking points of negotiations, and this year was no different. China (and others) want America to put up large sums of climate finance (to fund adaptation and mitigation in other countries), taking historical responsibility for their emissions, but America will not do this. Even Obama, who strongly supported Paris, would not agree to take responsibility for emissions before there was widespread acceptance of on climate change being anthropogenic.

In the past, developed and developing countries had differentiated responsibilities for mitigation of climate change, reflecting their different historical contributions and capabilities. Only “Annex I” (“developed”) countries such as the EU, USA and Canada had mitigation targets and financial opbligations under the Kyoto Protocol. Economies in Transition (such as China) and developing countries did not. Moving forward in Paris, the process of countries setting their own targets (Nationally Determined Contributions) gave all countries responsibilities but also control over their own action, reducing the need for formalised differentiation.

China remains keen to retain formal differentiation, but many at the conference began to question the legitimacy of China’s appeals for finance and differentiation when they have become the largest pollution nation (albeit with lower per capita emissions that America) and one of the most rapidly growing economies.

Reconnecting with the lived experience of climate change

There was an overwhelming number of science talks at a huge verity of side events. For me though, the best thing about COP was the opportunity to mix with people, hear stories and go to talks that I wouldn’t normally get the chance to. It takes me away from my number crunching to hear how people are experiencing climate change, to talk about the realities of adaption and mitigation, to remind us how the world really works outside of computer models.

Talking to a young African man and an indigenous Guatemalan woman about how people are experiencing climate change now, they explained that people often don’t really know that that is the reason their crops have failed three years running, or there are more regular storms of higher intensity, or their houses are washing away. They are worrying how to feed themselves and pay for their kids to go to school. They are not concerned with how they can mitigate climate change, but how they can live.

Developing countries and indigenous groups attended in force, raising awareness of how climate change is affecting them now, and demanding action. These groups reconnected us with the urgency of the task at hand, and with the talks under the Presidency of Fiji this year, there was a loud and passionate voice from the Pacific Islands. Many islanders are already having to leave their homes due to sea level rise, salt water inundation of crops and drinking water aquifers – not to mention the series of increasingly frequent and devastating storms. One of the Island country negotiators told me that many other countries were keen to gain the favour of the Pacific Islands as the many countries (and therefore many votes) could lead them to become a powerful influencer.

A triumph or misfortune of participation?

One news article noted the five largest delegations were from African countries (nearly 500 from Cote d’Ivoire). While on the surface this is a major accomplishment, there were mutterings in the conference from younger African delegates that some senior colleagues had little interest in proceedings. While the importance of gender issues and climate was a major issue on the table at COP23, the proceedings also reflected other revelations of sexual misconduct with complaints of senior powerful male figures taking advantage of young female staff.

Some final thoughts

All in all, I have not come away from COP23 with the sense of achievement and exhilaration at the end of COP21 Paris, but a sense of urgency of the need to make it happen faster.

‘Young and future generations day’. Image credit: UNFCC

As Kevin Anderson from Tyndall said to me – we have known about this for some time now and yet we are failing, every one of us, to make anything happen at the scale and rate it needs to.

As I claw for answers on how to achieve this, I’m reminded that this year at COP there was a focus on youth. I saw some amazing youth speakers and participants, including one of our 3rd year undergraduate geography students. I also met two of our recent MSc graduates, one who was on the Mexican Delegation and one working for and NGO Climate Action Network.

I take great inspiration from these hugely talented young people, and they, alongside the impassioned and increasingly powerful voices of developing nations, offer hope. Whilst the responsibility for dealing with the implications of climate change should not rest solely in their hands – the devolution of power/ resource to those with fresh ideas and approaches could be exactly what we need to catalyse change.

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This blog is written by Jo House: Reader in Environmental science and policy, Department of Geographical Sciences, and Co-Chair of the Cabot Institute‘s Global Environmental Change research theme.

Jo House

How to turn a volcano into a power station – with a little help from satellites

Posted on November 7, 2017April 5, 2023 by janet.crompton

File 20171031 18735 1gapo0c.jpg?ixlib=rb 1.1

Erta Ale in eastern Ethiopia. mbrand85

Ethiopia tends to conjure images of sprawling dusty deserts, bustling streets in Addis Ababa or the precipitous cliffs of the Simien Mountains – possibly with a distance runner bounding along in the background. Yet the country is also one of the most volcanically active on Earth, thanks to Africa’s Great Rift Valley, which runs right through its heart.

Rifting is the geological process that rips tectonic plates apart, roughly at the speed your fingernails grow. In Ethiopia this has enabled magma to force its way to the surface, and there are over 60 known volcanoes. Many have undergone colossal eruptions in the past, leaving behind immense craters that pepper the rift floor. Some volcanoes are still active today. Visit them and you find bubbling mud ponds, hot springs and scores of steaming vents.

Steam rising at Aluto volcano, Ethiopia. William Hutchison

This steam has been used by locals for washing and bathing, but underlying this is a much bigger opportunity. The surface activity suggests extremely hot fluids deep below, perhaps up to 300°C–400°C. Drill down and it should be possible access this high temperature steam, which could drive large turbines and produce huge amounts of power. This matters greatly in a country where 77% of the population has no access to electricity, one of the lowest levels in Africa.

Geothermal power has recently become a serious proposition thanks to geophysical surveys suggesting that some volcanoes could yield a gigawatt of power. That’s the equivalent of several million solar panels or 500 wind turbines from each. The total untapped resource is estimated to be in the region of 10GW.

Converting this energy into power would build on the geothermal pilot project that began some 20 years ago at Aluto volcano in the lakes region 200km south of Addis Ababa. Its infrastructure is currently being upgraded to increase production tenfold, from 7MW to 70MW. In sum, geothermal looks like a fantastic low-carbon renewable solution for Ethiopia that could form the backbone of the power sector and help lift people out of poverty.

Scratching the surface

The major problem is that, unlike more developed geothermal economies like Iceland, very little is known about Ethiopia’s volcanoes. In almost all cases, we don’t even know when the last eruption took place – a vital question since erupting volcanoes and large-scale power generation will not make happy bedfellows.

In recent years, the UK’s Natural Environment Research Council (NERC) has been funding RiftVolc, a consortium of British and Ethiopian universities and geological surveys, to address some of these issues. This has focused on understanding the hazards and developing methods for exploring and monitoring the volcanoes so that they can be exploited safely and sustainably.

Teams of scientists have been out in the field for the past three years deploying monitoring equipment and making observations. Yet some of the most important breakthroughs have come through an entirely different route – through researchers analysing satellite images at their desks.

This has produced exciting findings at Aluto. Using a satellite radar technique, we discovered that the volcano’s surface is inflating and deflating. The best analogy is breathing – we found sharp “inhalations” inflating the surface over a few months, followed by gradual “exhalations” which cause slow subsidence over many years. We’re not exactly sure what is causing these ups and downs, but it is good evidence that magma, geothermal waters or gases are moving around in the depths some five km below the surface.

Taking the temperature

In our most recent paper, we used satellite thermal images to probe the emissions of Aluto’s steam vents in more detail. We found that the locations where gases were escaping often coincided with known fault lines and fractures on the volcano.

When we monitored the temperature of these vents over several years, we were surprised to find that most were quite stable. Only a few vents on the eastern margin showed measurable temperature changes. And crucially, this was not happening in synchronicity with Aluto’s ups and downs – we might have expected that surface temperatures would increase following a period of inflation, as hot fluids rise up from the belly of the volcano.

A productive geothermal well on Aluto. William Hutchison

It was only when we delved into the rainfall records that we came up with an explanation: the vents that show variations appear to be changing as a delayed response to rainfall on the higher ground of the rift margin. Our conclusion was that the vents nearer the centre of the volcano were not perturbed by rainfall and thus represent a better sample of the hottest waters in the geothermal reservoir. This obviously makes a difference when it comes to planning where to drill wells and build power stations on the volcano, but there’s a much wider significance.

This is one of the first times anyone has monitored a geothermal resource from space, and it demonstrates what can be achieved. Since the satellite data is freely available, it represents an inexpensive and risk-free way of assessing geothermal potential.

With similar volcanoes scattered across countries like Kenya, Tanzania and Uganda, the technique could allow us to discover and monitor new untapped geothermal resources in the Rift Valley as well as around the world. When you zoom back and look at the big picture, it is amazing what starts to come into view.
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This blog is written by William Hutchison, Research Fellow, University of St Andrews; Juliet Biggs, Reader in Earth Sciences and Cabot Institute member, University of Bristol, and Tamsin Mather, Professor of Earth Sciences, University of Oxford

This article was originally published on The Conversation. Read the original article.
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Juliet Biggs is a member of the University of Bristol Cabot Institute. She studies Continental Tectonics and Volcanic Deformation and has won numerous awards in her field. Find out more about Juliet Biggs research.