Tag: ocean

Just the tip of the iceberg: Climate research at the Bristol Glaciology Centre

Posted on by janet.crompton

As part of Green Great Britain Week, supported by BEIS, we are posting a series of blogs throughout the week highlighting what work is going on at the University of Bristol’s Cabot Institute for the Environment to help provide up to date climate science, technology and solutions for government and industry.  We will also be highlighting some of the big sustainability actions happening across the University and local community in order to do our part to mitigate the negative effects of global warming. Today our blog will look at ‘Explaining the latest science on climate change’.

Last week the Intergovernmental Panel on Climate Change (IPCC) released its special report on the impact of global warming of 1.5˚C. Professor Tony Payne – Head of the University of Bristol’s School of Geographical Sciences and Bristol Glaciology Centre (BGC) member – is one of the lead authors on the report, which highlights the increased threats of a 2˚C versus 1.5˚C warmer world. The report also lays out the mitigation pathways that must be taken if we are to meet the challenge of keeping global warming to 1.5˚C above pre-industrial levels.

The core of the report is a synthesis of over 6000 scientific papers detailing our current understanding of the climate system, and here at the BGC our research is focused on the role of the cryosphere in that system. The cryosphere, which refers to all the snow, ice and permafrost on the planet, is changing rapidly under global warming, and understanding how it will continue to evolve is critical for predicting our future climate. This is primarily due to the positive feedback loops in which it is involved, whereby a small change in conditions sets off a sequence of processes that reinforce and amplify the initial change. Despite the name, in the context of our current climate these positive feedback loops are almost always bad news and are responsible for some of the “tipping points” that could lead to runaway changes in the climate system.

I hope this post will give you a quick tour of just some of the research being carried out by scientists at the BGC, studying the way in which mountain glaciers, sea ice and the two great ice sheets of Antarctica and Greenland are responding to and influencing our changing climate.

Ice sheets

My own research examines ice flow at the margins of Antarctica. The Antarctic ice sheet is fringed by floating ice shelves, fed by large glaciers and ice streams that flow from the heart of the ice sheet towards the coast (see Figure 1). These ice shelves can provide forces that resist the glaciers that flow into them, reducing their speed and the amount of ice that enters the ocean. Crucially, once ice flows off the land and begins to float it causes the sea level to rise. My work is in modelling the interaction between ice shelves and the rest of the ice sheet to better quantify the role that ice shelves have in restraining ice loss from the continent. This will help to reduce the uncertainty in our predictions of future sea level rise, as the thinning and collapse of Antarctic ice shelves that we have seen in recent decades looks set to continue.

Figure 1: Schematic of the Antarctic ice sheet grounding line. Image credit: Bethan Davies, www.AntarcticGlaciers.org

To model ice flow in Antarctica with any success it is crucial to know the exact location of the point at which the ice sheet begins to float, called the ‘grounding line’. Research on this within the BGC is being done by Dr Geoffrey Dawson and Professor Jonathan Bamber, using data from the European Space Agency’s CryoSat-2 satellite. Their method determines the location of the grounding line by measuring the rise and fall of the floating ice shelves under the influence of ocean tides. Recently published work from this project has improved our knowledge of the grounding line location near the Echelmeyer ice stream in West Antarctica and this method is currently being rolled out across the rest of the ice sheet [1].

In the Northern Hemisphere, the Black and Bloom project led by Professor Martyn Tranter is studying ice algae on the second largest ice mass on Earth, the Greenland Ice Sheet (GrIS). The large, dark regions that appear on the GrIS in the summer are, in part, down to blooms of algae growing in the presence of meltwater on the ice sheet (see Figure 2). This bloom is darker than the surrounding ice surface and so reduces the albedo (a measure, between 0 and 1, of a surface’s reflectivity). A reduced ice sheet albedo means more of the sun’s energy is absorbed and the surface becomes warmer, which produces more meltwater, and more algae, leading to more energy absorption in a classic example of a positive feedback loop. The aim of the project, a partnership between biologists and glaciologists within the BGC, is to take measurements of algal growth and to incorporate their effect on albedo into climate models. A recent paper from the group, led by Dr Chris Williamson, revealed the abundance and species of microbial life that are growing on the GrIS [2], and this summer the team returned to the field to extend their work to more northerly regions of the ice sheet.

Figure 2: Bags of surface ice collected on the Greenland Ice Sheet showing the change in albedo with (from left to right) low, medium and high amounts of algae present.

Sea ice

Moving from land-based ice and into the ocean, Arctic sea ice is also being studied within the BGC. Regions of the Arctic have warmed at over 3 times the global average during the last century and there has consequently been a dramatic decline in the amount of sea ice that survives the summer melt season. The minimum, summer Arctic sea ice extent is currently declining at 13.2% per decade. Predicting the future of Arctic sea ice is critical for understanding global climate change due to the presence of another positive feedback loop: reduced summer sea ice replaces the white, high albedo ice surface with the darker, low albedo, ocean surface. This means that more solar energy is absorbed, raising surface temperatures and increasing ice melt, leading to more exposed ocean and further warming.

Dr Jack Landy has used remote sensing data from satellites, including CryoSat-2 and ICESat, to measure the roughness of Arctic sea ice and to model the impact that changing roughness has on albedo (see Figure 3). The roughness of the sea ice controls the size of the meltwater ponds that can form on the surface. With less sea ice lasting through multiple summer melt seasons, the trend is for Arctic sea ice to become smoother, allowing larger and larger ponds to form which, again, have a lower albedo than the ice surface they sit on, creating yet another positive feedback loop [3].

Figure 3: Panels a and b are predictions for summer (June to August) Arctic sea ice albedo based upon ice roughness observations made in March of 2005 and 2007 respectively. Panels c and d show the actual, observed summer albedo in those years. Image credit: Dr Jack Landy [3].

Mountain glaciers

A third element of the cryosphere studied at the BGC are glaciers in high mountain regions such as the Andes and the Himalayas. Led by Professor Jemma Wadham, the new Director of the Cabot Institute, this work focuses on the biology and chemistry of the meltwater produced from these glaciers. This summer a team of postgraduate researchers from the BGC – Rory Burford, Sarah Tingey and Guillaume Lamarche-Gagnon – travelled to the Himalayas in partnership with Jawaharlal Nehru University, New Delhi, to collect meltwater samples from the streams emanating from the Chhota Shigri glacier. These streams eventually flow into the Indus river, a vital water source for agriculture and industry in Pakistan. It is therefore crucial to understand how the quality of this water source might change in a warmer climate. Mercury, for example, is precipitated out of the atmosphere by snowfall and can collect and become concentrated within these high mountain glaciers. In the shorter term, if these glaciers continue to melt more rapidly, larger amounts of mercury will be released into the environment and will impact the quality of water that supports millions of people. On longer time scales, the retreat and reduction in volume of the Himalayan glaciers will reduce the amount of water supplied to communities downstream, with huge implications for water security in the region.

Figure 4: Photo from Himalayan fieldwork. Image credit: Guillaume Lamarche-Gagnon

Outlook

This is just the tip of the BGC research iceberg, with field data from this summer currently being pored over and new questions being developed. This work will hopefully inform the upcoming IPCC special report on the oceans and cryosphere (due in 2019), which is set to be another significant chance to assess and share our understanding of the ice on our planet and what it means for the challenges we have set for ourselves in tackling climate change.

References

[1] Dawson, G. J., & Bamber, J. L. (2017). Antarctic grounding line mapping from CryoSat‐2 radar altimetry. Geophysical Research Letters, 44, 11,886–11,893. https://doi.org/10.1002/2017GL075589

[2] Williamson, C. J., Anesio, A. M., Cook, J., Tedstone, A., Poniecka, E., Holland, A., Fagan, D., Tranter, M., & Yallop, M. L. (2018). ‘Ice algal bloom development on the surface of the Greenland Ice Sheet’. FEMS Microbiology Ecology, 94,3. https://doi.org/10.1093/femsec/fiy025

[3] Landy, J. C., J. K. Ehn, and D. G. Barber (2015). Albedo feedback enhanced by smoother Arctic sea ice. Geophysical Research Letters, 42, 10,714–10,720. https://doi.org/10.1002/2015GL066712

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This blog was written by Cabot Institute member Tom Mitcham. He is a PhD student in the School of Geographical Sciences at the University of Bristol and is studying the ice dynamics of Antarctic ice shelves and their tributary glaciers.

Tom Mitcham

Read other blogs in this Green Great Britain Week series:
1. Just the tip of the iceberg: Climate research at the Bristol Glaciology Centre
2. Monitoring greenhouse gas emissions: Now more important than ever?
3. Digital future of renewable energy
4. The new carbon economy – transforming waste into a resource
5. Systems thinking: 5 ways to be a more sustainable university
6. Local students + local communities = action on the local environment

Unless we regain our historic awe of the deep ocean, it will be plundered

Posted on by janet.crompton
File 20171107 1017 1vsenhn.jpg?ixlib=rb 1.1
Image credit: BBC Blue Planet

In the memorable second instalment of Blue Planet II, we are offered glimpses of an unfamiliar world – the deep ocean. The episode places an unusual emphasis on its own construction: glimpses of the deep sea and its inhabitants are interspersed with shots of the technology – a manned submersible – that brought us these astonishing images. It is very unusual and extremely challenging, we are given to understand, for a human to enter and interact with this unfamiliar world.The most watched programme of 2017 in the UK, Blue Planet II provides the opportunity to revisit questions that have long occupied us. To whom does the sea belong? Should humans enter its depths? These questions are perhaps especially urgent today, when Nautilus Minerals, a mining company registered in Vancouver, has been granted a license to extract gold and copper from the seafloor off the coast of Papua New Guinea. Though the company has suffered some setbacks, mining is still scheduled to begin in 2019.

Blue Planet’s team explore the deep. Image credit BBC/Blue Planet

This marks a new era in our interaction with the oceans. For a long time in Western culture, to go to sea at all was to transgress. In Seneca’s Medea, the chorus blames advances in navigation for having brought the Golden Age to an end, while for more than one Mediterranean culture to travel through the Straits of Gibraltar and into the wide Atlantic was considered unwisely to tempt divine forces. The vast seas were associated with knowledge that humankind was better off without – another version, if you will, of the apple in the garden.

If to travel horizontally across the sea was to trespass, then to travel vertically into its depths was to redouble the indiscretion. In his 17th-century poem Vanitie (I), George Herbert writes of a diver seeking out a “pearl” which “God did hide | On purpose from the ventrous wretch”. In Herbert’s imagination, the deep sea is off limits, containing tempting objects whose attainment will damage us. Something like this vision of the deep resurfaces more than 300 years later in one of the most startling passages of Thomas Mann’s novel Doctor Faustus (1947), as a trip underwater in a diving bell figures forth the protagonist’s desire for occult, ungodly knowledge.

An early diving bell used by 16th century divers. National Undersearch Research Program (NURP)

Mann’s deep sea is a symbolic space, but his reference to a diving bell gestures towards the technological advances that have taken humans and their tools into the material deep. Our whale-lines and fathom-lines have long groped into the oceans’ dark reaches, while more recently deep-sea cables, submarines and offshore rigs have penetrated their secrets. Somewhat paradoxically, it may be that our day-to-day involvement in the oceans means that they no longer sit so prominently on our cultural radar: we have demystified the deep, and stripped it of its imaginative power.

But at the same time, technological advances in shipping and travel mean that our culture is one of “sea-blindness”: even while writing by the light provided by oil extracted from the ocean floor, using communications provided by deep-sea cables, or arguing over the renewal of Trident, we perhaps struggle to believe that we, as humans, are linked to the oceans and their black depths. This wine bottle, found lying on the sea bed in the remote Atlantic, is to most of us an uncanny object: a familiar entity in an alien world, it combines the homely with the unhomely.

Wine bottle found in the deep North Atlantic. Laura Robinson, University of Bristol, and the Natural Environment Research Council. Expedition JC094 was funded by the European Research Council.

For this reason, the activities planned by Nautilus Minerals have the whiff of science fiction. The company’s very name recalls that of the underwater craft of Jules Verne’s adventure novel Twenty Thousand Leagues under the Seas (1870), perhaps the most famous literary text set in the deep oceans. But mining the deep is no longer a fantasy, and its practice is potentially devastating. As the Deep Sea Mining Campaign points out, the mineral deposits targeted by Nautilus gather around hydrothermal vents, the astonishing structures which featured heavily in the second episode of Blue Planet II. These vents support unique ecosystems which, if the mining goes ahead, are likely to be destroyed before we even begin to understand them. (Notice the total lack of aquatic life in Nautilus’s corporate video: they might as well be drilling on the moon.) The campaigners against deep sea mining also insist – sounding not unlike George Herbert – that we don’t need the minerals located at the bottom of the sea: that the reasons for wrenching them from the deep are at best suspect.

So should we be leaving the deep sea well alone? Sadly, it is rather too late for that. Our underwater cameras transmit images of tangled fishing gear, cables and bottles strewn on the seafloor, and we find specimens of deep sea animals thousands of metres deep and hundreds of kilometres away from land with plastic fibres in their guts and skeletons. It seems almost inevitable that deep sea mining will open a new and substantial chapter on humanity’s relationship with the oceans. Mining new resources is still perceived to be more economically viable than recycling; as natural resources become scarcer, the ocean bed will almost certainly become of interest to global corporations with the capacity to explore and mine it – and to governments that stand to benefit from these activities. These governments are also likely to compete with one another for ownership of parts of the global ocean currently in dispute, such as the South China Sea and the Arctic. The question is perhaps not if the deep sea will be exploited, but how and by whom. So what is to be done?

A feather star in the deep waters of the Antarctic. BBC NHU
Rather than declaring the deep sea off-limits, we think our best course of action is to regain our fascination with it. We may have a toe-hold within the oceans; but, as any marine scientist will tell you, the deep still harbours unimaginable secrets. The onus is on both scientists and those working in what has been dubbed the “blue humanities” to translate, to a wider public, the sense of excitement to be found in exploring this element. Then, perhaps, we can prevent the deep ocean from becoming yet another commodity to be mined – or, at least, we can ensure that such mining is responsible and that it takes place under proper scrutiny.
The sea, and especially the deep sea, will never be “ours” in the way that tracts of land become cities, or even in the way rivers become avenues of commerce. This is one of its great attractions, and is why it is so easy to sit back and view the deep sea with awed detachment when watching Blue Planet II. But we cannot afford to pretend that it lies entirely beyond our sphere of activity. Only by expressing our humility before it, perhaps, can we save it from ruthless exploitation; only by acknowledging and celebrating our ignorance of it can we protect it from the devastation that our technological advances have made possible.-
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This blog is written by Laurence Publicover, Lecturer in English, University of Bristol and Katharine Hendry, Reader in Geochemistry, University of Bristol and both members of the University’s Cabot Institute. This article was originally published on The Conversation. Read the original article.

What happens when you cross a venture capitalist with a major national scientific research organisation?

Posted on by janet.crompton
CSIRO Corporate Headquarters, Campbell. Image credit: Bidgee – Own work, CC BY-SA 3.0

I’m not sure if there’s a punchline, instead just a rather alarming answer. A couple of days ago, over on the other side of the world, Larry Marshall, the chief executive of Australia’s government agency for scientific research, made a disturbing announcement. Australia’s national science agency, CSIRO (the Commonwealth Scientific and Industrial Research Organisation) is to face a further 350 job losses (over 5% of its workforce) over the next two years. Primarily these losses look to be from the Oceans and Atmosphere division, affecting ongoing work on monitoring and predicting the Earth’s climate.

The job losses themselves are a huge blow for Australian and global climate research, and give the impression that the current Australian regime are perhaps not totally committed to upholding their end of the Paris agreement. This doesn’t say much, given that the Australian commitments were widely derided for being pretty weak in the first place.

So why is CSIRO’s current work important? Taking just one example, CSIRO plays a key role in monitoring the current state of the atmosphere, positioned as it is in one of the few countries in the Southern Hemisphere with well-developed scientific infrastructure. The Cape Grim atmospheric monitoring station in Tasmania, has been recording levels of southern hemisphere greenhouse gases for the last 40 years. The station mostly receives air that has travelled over the southern ocean free from pollution sources, thus providing a key record of southern hemisphere background levels of various atmospheric constituents. It’s basically the southern hemisphere equivalent of the Mauna Loa station in Hawaii which is regularly used as the key yardstick for northern hemisphere background levels.

Long term records like this are kind of pretty important, not just for scientific investigation, but also as an aid to public outreach. Anyone could look at these graphs of Cape Grim data for the three most abundant greenhouse gases, and pick up the take home message: they’ve all been increasing since the 1970s.

The point is that the Cape Grim measurements have played a key role in our understanding of the changes in the atmosphere over last 40 years, and should continue to do so into the future. Except maybe they won’t. If reports are to be believed it’s exactly this type of infrastructure that is under threat. Reportedly 100 people are to be unceremoniously thrown out to pasture from the Oceans and Atmosphere division, leaving just 30 left. Such a remarkably high turnover will have an inevitable effect on the quality of continuing work, not to mention quantity.

Perhaps that is what the current government in Australia want though. Less data might create more uncertainty, giving them a justification to do even less about it. But, even that view has previously been countered by the Cabot Institute’s Richard Pancost and Stephan Lewandowsky who explained why more uncertainty is no excuse for doing nothing.

Alternatively, you could take the opinion that maybe it’s not the Australian government’s responsibility to directly fund this sort of research. But, these sort of long-term records require secure long-term funding, the like of which are not found in the competitive world of academia. It’s no good chopping and changing grants every 3 years, funding different universities for different stations. There would be no consistency in the record, and suddenly any increases you see might be more attributable to a change in location than a real-world signal.

Perhaps the most alarming aspect of this is the misleading justification for the cuts, by saying that the question of global climate change has been answered. Sure, there is a consensus that human activities are affecting our climate, but that’s like saying there’s a consensus that it will rain tomorrow. It leaves questions unanswered, such as where and when?

Actually, to make matters worse the CEO added that “after Paris” the question of global climate change had been answered. Hold on, since when was it a group of politicians who were to decide whether large-scale global environmental change was happening or not? And haven’t we known about this for a good deal longer than the last three months?

Ignoring these inaccurate attempts to justify the decision, a better explanation is found in Marshall’s stated goal to make CSIRO more focused on innovation and commercialisation. The problem is, that monitoring the current state of the oceans and atmosphere or predicting its long-term future just isn’t a great commercial venture. It’s the sort of research that takes in a fair bit of funding, but doesn’t seem to offer any immediate financial return. Telling Joe Banker the world will be 2 °C warmer in 100 years isn’t going to cause the stock market to rise or fall.

That seems to contrast with weather prediction, which seems to be a profitable business. A quick look at the UK Met Office financial statements reveals over £220m in revenue in the last financial year. Admittedly most of this is from government contracts (a case of moving money round departments), but over 10% is from commercial revenue, whether that be aviation, or maybe supermarkets wanting to know whether to stock barbecues at the weekend or not. Losing the BBC contract may have been a PR disaster, but financially it was clearly not the worst thing that could have happened.

The point is that weather prediction pays. It’s a short-term prediction that is easily evaluated, allowing people to judge the value for money it gives.

Is there some way we can put a similar value on climate monitoring and prediction? I suspect not, given it would run against scientific principles of openness and be much harder to judge its worth. I imagine Larry Marshall came to the same conclusion, but then that really calls into question whether he’s really pulling his weight at CSIRO. You can’t expect all responsibility to make CSIRO profitable to fall on employees who have no entrepreneurial experience.

If more recent reports are to be believed, this move has come as a shock to even the Australian Prime Minister, and so perhaps there is hope that the news of CSIRO’s climate science death are premature. Even so, funding issues are hardly peculiar to Australia, and the question of whether climate science can fit into modern commercial ideals will inevitably keep cropping up across the globe.

It remains to be seen what exactly will happen but severe cuts to CSIRO’s infrastructure and staff will affect not just Australian science, but have global implications as well. The name Cape Grim has always struck me as being slightly ominous, and aptly (or cruelly) its 40th anniversary celebrations were due to take place later this year. Somehow I can’t imagine there will be too many people in the mood for celebrating right now though.

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This blog has been written by Cabot Institute member Mark Lunt, from the University of Bristol’s Atmospheric Chemistry Research Group.  Mark’s main area of research is in the estimation of greenhouse gas emissions from atmospheric measurements.

Ancient ‘dead seas’ offer a stark warning for our own near future

Posted on by janet.crompton
Bristol during the pleiocene as envisaged by Lucas Antics.

The oceans are experiencing a devastating combination of stresses. Rising CO2 levels are raising temperatures while acidifying surface waters.  More intense rainfall events, deforestation and intensive farming are causing soils and nutrients to be flushed to coastal seas. And increasingly, the oceans are being stripped of oxygen, with larger than expected dead zones being identified in an ever broadening range of settings. These dead zones appear to be primarily caused by the runoff of nutrients from our farmlands to the sea, but it is a process that could be exacerbated by climate change – as has happened in the past.

Recently, our group published a paper about the environmental conditions of the Zechstein Sea, which reached from Britain to Poland 270 million years ago. Our paper revealed that for tens of thousands of years, some parts – but only parts – of the Zechstein Sea were anoxic (devoid of oxygen). As such, it contributes to a vast body of research, spanning the past 40 years and representing the efforts of hundreds of scientists, which has collectively transformed our understanding of ancient oceans – and by extension future ones.

The types of processes that bring about anoxia are relatively well understood. Oxygen is consumed by animals and bacteria as they digest organic matter and convert it into energy. In areas where a great deal of organic matter has been produced and/or where the water circulation is stagnant such that the consumed oxygen cannot be rapidly replenished, concentrations can become very low. In severe cases, all oxygen can be consumed rendering the waters anoxic and inhospitable to animal life.  This happens today in isolated fjords and basins, like the Black Sea.  And it has happened throughout Earth history, allowing vast amounts of organic matter to escape degradation, yielding the fossil fuel deposits on which our economy is based, and changing the Earth’s climate by sequestering what had once been carbon dioxide in the atmosphere into organic carbon buried in sediments.

Red circles show the location and size of many dead zones. Black dots show Ocean dead zones of unknown size. Image source: Wikimedia Commons/NASA Earth Observatory

In some cases, this anoxia appears to have been widespread; for example, during several transient Cretaceous events, anoxia spanned much of what is now the Atlantic Ocean or maybe even almost all of the ancient oceans. These specific intervals were first identified and named oceanic anoxic events in landmark work by Seymour Schlanger and Hugh Jenkyns.  In the 1970s, during the earliest days of the international Deep Sea Drilling Program (now the International Ocean Discovery Program, arguably the longest-running internationally coordinated scientific endeavor), they were the first to show that organic matter-rich deep sea deposits were the same age as similar deposits in the mountains of Italy. Given the importance of these deposits for our economy and our understanding of Earth and life history, scientists have studied them persistently over the past four decades, mapping them across the planet and interrogating them with all of our geochemical and palaeontological resources.

In my own work, I have used the by-products of certain bacterial pigments to interrogate the extent of that anoxia.  The organisms are green sulfur bacteria (GSB), which require both sunlight and the chemical energy of hydrogen sulfide in order to conduct a rather exotic form of bacterial photosynthesis; crucially, hydrogen sulfide is only formed in the ocean from sulfate after the depletion of oxygen (because the latter yields much more energy when used to consume organic matter). Therefore, GSB can only live in a unique niche, where oxygen poor conditions have extended into the photic zone, the realm of light penetration at the very top of the oceans, typically only the upper 100 m.  However, GSB still must compete for light with algae that live in even shallower and oxygen-rich waters, requiring the biosynthesis of light harvesting pigments distinct from those of plants, the carotenoids isorenieratene, chlorobactene and okenone. For the organism, this is an elegant modification of a molecular template to a specific ecological need. For the geochemist, this is an astonishingly fortuitous and useful synthesis of adaptation and environment – the pigments and their degradation products can be found in ancient rocks, serving as molecular fossil evidence for the presence of these exotic and diagnostic organisms.

And these compounds are common in the black shales that formed during oceanic anoxic events.  And in particular, during the OAE that occurred 90 million years ago, OAE2, they are among the most abundant marker compounds in sediments found throughout the Atlantic Ocean and the Tethyan Ocean, what is now the Mediterranean Sea.  It appears that during some of these events anoxia extended from the seafloor almost all the way to the ocean’s surface.

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Today, the deep sea is a dark and empty world. It is a world of animals and Bacteria and Archaea – and relatively few of those. Unlike almost every other ecosystem on our planet, it is bereft of light and therefore bereft of plants.  The animals of the deep sea are still almost entirely dependent on photosynthetic energy, but it is energy generated kilometres above in the thin photic zone. Beneath this, both animals and bacteria largely live off the scraps of organic matter energy that somehow escape the vibrant recycling of the surface world and sink to the twilight realm below. In this energy-starved world, the animals live solitary lives in emptiness, darkness and mystery. Exploring the deep sea via submersible is a humbling and quiet experience.  The seafloor rolls on and on and on, with only the occasional shell or amphipod or small fish providing any evidence for life.

“Krill swarm” by Jamie Hall – NOAA. Licensed under Public Domain via Wikimedia Commons

And yet life is there.  Vast communities of krill thrive on the slowly sinking marine snow, can appear.  Sperm whales dive deep into the ocean to consume the krill and emerge with the scars of fierce battles with giant squid.  And when one of those great creatures dies and its carcass plummets to the seafloor, within hours it is set upon by sharks and fish, ravenous and emerging from the darkness for the unexpected feast. Within days the carcass is stripped to the bones but even then new colonizing animals arrive and thrive. Relying on bacteria that slowly tap the more recalcitrant organic matter that is locked away in the whale’s bones, massive colonies of tube worms spring to life, spawn and eventually die.

But all of these animals, the fish, whales, tube worms and amphipods, depend on oxygen. And the oceans have been like this for almost all of Earth history, since the advent of multicellular life nearly a billion years ago.

This oxygen-replete ocean is an incredible contrast to the north Atlantic Ocean during at least some of these anoxic events. Then, plesiosaurs, ichthyosaurs and mosasaurs, feeding on magnificent ammonites, would have been confined to the sunlit realm, their maximum depth of descent marked by a layer of surprisingly pink and then green water, pigmented by the sulfide consuming bacteria.  And below it, not a realm of animals but a realm only of Bacteria and Archaea, single-celled organisms that can live in the absence of oxygen, a transient revival of the primeval marine ecosystems that existed for billions of years before more complex life evolved.

We have found evidence for these types of conditions during numerous events in Earth history, often associated with major extinctions, including the largest mass extinction in Earth history – the Permo-Triassic Boundary 252 million years ago.  Stripping the ocean of oxygen and perhaps even pumping toxic hydrogen sulfide gas into the atmosphere is unsurprisingly associated with devastating biological change.   It is alarming to realise that under the right conditions our own oceans could experience this same dramatic change.  Aside from its impact on marine life, it would be devastating for us, so dependent are we on the oceans for our food.

The conventional wisdom has been that such extreme anoxia in the future is unlikely, that Cretaceous anoxia was a consequence of a markedly different geography.  North America was closer to Europe and South America only completely rifted from Africa about 150 million years ago; the ancient Atlantic Ocean was smaller and more restricted, lending itself to these extreme conditions.

And yet questions remain.  What was their trigger?  Was it really a happenstance of geography?  Or was it due to environmental perturbations? And how extensive were they? The geological record preserves only snapshots, limiting the geographical window into ancient oceans, and this is a window that narrows as we push further back in time. In one of our recent papers, we could not simulate such severe anoxia in the Atlantic Ocean without also simulating anoxia throughout the world’s oceans, a truly global oceanic anoxic event.  However, that model can only constrain some aspects of ocean circulation and there are likely alternative mechanisms that confine anoxia to certain areas.

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Over the past twenty years, these questions have intersected one another and been examined again and again via new models, new geochemical tools and new ideas.  And an emerging idea is that the geography of the Mesozoic oceans was not as important as we have thought.

That classical model is that ancient oceans, through a combination of the aforementioned restricted geography and overall high temperatures, were inherently prone to anoxia.  In an isolated Atlantic Ocean, oxygen replenishment of the deep waters would have been much slower.  This would have been exaggerated by the higher temperatures of the Cretaceous, such that oxygen solubility was lower (i.e. for a given amount of oxygen in the atmosphere, less dissolves into seawater) and ocean circulation was more sluggish. Consequently, these OAEs could have been somewhat analogous to the modern Black Sea.  The Black Sea is a restricted basin with a stratified water column, formed by low density fresh water derived from the surrounding rivers sitting stably above salty and dense marine deep water. The freshwater lid prevents mixing and prevents oxygen from penetrating into deeper waters. Concurrently, nutrients from the surrounding rivers keep algal production high, ensuring a constant supply of sinking organic matter, delicious food for microbes to consume using the last vestiges of oxygen.  The ancient oceans of OAEs were not exactly the same but perhaps similar processes were operating. Crucially, the configuration of ancient continents in which major basins were isolated from one another, suggests a parallel between the Black Sea and the ancient North Atlantic Ocean.

But over the past twenty years, that model has proved less and less satisfactory.  First, it does not provide a mechanism for the limited temporal occurrence of the OAEs.  If driven solely by the shape of our oceans and the location of our continents, why were the oceans not anoxic as the norm rather than only during these events? Second, putative OAEs, such as that at the Permo-Triassic Boundary occur at times when the oceans do not appear to have been restricted.  Third, coupled ocean-atmosphere models indicate that although ocean circulation was slower under these warmer conditions, it did not stop.

But also, as we have looked more and more closely at those small windows into the past, we have learned that during some of these events anoxia was more restricted to coastal settings.  And that brings us back to the Zechstein Sea. We mapped the extent of anoxia at an unprecedented scale in cores drilled by the Polish Geological Survey, and we discovered an increasing abundance of GSB molecular fossils in rocks extending from the carbonate platform and down the continental slope, suggesting that anoxia had extended out into the wider sea.  But when we reached the deep central part of the basin, the fossils were absent.  In fact, the sediments contained the fossils of benthic foraminifera, oxygen dependent organisms living at the seafloor, and the sediments had been bioturbated, churned by ancient animals. The green sulfur bacteria and the anoxia were confined to the edge of the basin, completely unlike the Black Sea.  This is not the first such observation and this is consistent with new arguments mandating not only a different schematic but also a different trigger.  And perhaps that trigger was from outside of the oceans.

If the trigger was not solely a restriction of oxygen supply then the alternative is that it was an excess of organic matter, the degradation of which consumed the limited oxygen. A likely source of that organic matter and one that is consistent with restriction of anoxia to ocean margins is a dramatic increase in nutrients that stimulated algal blooms – much like what is occurring today.  And that increase in nutrients, as elegantly summarized by Hugh Jenkyns, could have been caused by an increase in erosion and chemical weathering, driven by higher carbon dioxide concentrations, global warming and/or changes in the hydrological cycle, all of which we now know occurred prior to several OAEs. And again, similar to what is occurring today.

It is likely that today’s coastal dead zones are due not to climate change but to how we use our land and especially to our excess and indiscriminate use of fertilisers, most of which does not help crops grow or enhance our soil quality but is instead washed away to pollute our rivers and coastal seas. And yet that only underscores the lessons of the past.  They suggest that global warming might exacerbate the impacts of our poor land management, adding yet another pressure to an already stressed ecosystem.

Runoff of soil and fertiliser  during a rain storm. Image source: Wikimedia Commons

The Zechstein Sea study is not the key to this new paradigm (and that ‘paradigm’ is far from settled).  There is probably no single study that marked our change in understanding.  Instead, this new model has been gradually emerging over nearly 20 years, as long as I have been studying these events. New geochemical data, such as the distribution of nutrient elements, suggest that many of these anoxic episodes, whether local or global, were associated with algal blooms.  And other geochemical tools, such as the isotopic composition of trace metals, provide direct evidence for changes in the chemical weathering that liberated the bloom-fueling nutrients.

Science can move in monumental leaps forward but more typically it evolves in small steps. Sometimes, after years of small steps, your understanding has fundamentally changed. And sometimes that change means that your perception of the world, the world you love and on which you depend, has also changed.  You realize that it is more dynamic than you thought – as is its vulnerability to human behaviour.
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This blog is by Prof Rich Pancost, Director of the Cabot Institute at the University of Bristol. 
A shortened version of this blog can be found on The Conversation.
Prof Rich Pancost

This blog has also appeared in IFL Science and The Ecologist.

Public debates in science: Where’s the balance?

Posted on by janet.crompton

Earth Science PhD student Peter Spooner shares his experiences after working as a science-policy intern at the British Library, struggling to achieve scientific balance in a politically charged debate.

Greenpeace’s Will McCallum talks to Barrie Deas of the NFFO at TalkScience.
© The British Library Board

Anyone who follows any kind of environmental science will be aware of the differences in the ways that science can be portrayed – be it in the news, in TV shows, on the radio or at public events. As an organiser/reporter, a debate is often a good way to make your event/article more interesting, and there are almost always different points of view clamouring to be heard. It is often straightforward for a scientist specialising in a topic to point to a media debate of the issue and say: ‘That debate did not represent the scientific position’. However, as I discovered during my recent internship at the British Library, trying to organise a properly balanced debate is very difficult and may not always be the goal to which every debate aspires.

The British Library’s TalkScience series are discussion-style events focussing on topical issues in science. Past events have included topics such as: climate change and extreme weather; the impact of pesticides on bees; genetic modification on the farm and many more, all topics with relevance to political/social issues as well as science. When designing my event, my oceanographic background (along with having a scuba diver’s love for all things marine) led me to choose the title ‘Fishing and Marine Protection: What’s the Catch?’ The discussion would focus on the increasing pressure under which we are placing our marine environment and the impacts that has on the life beneath the waves and the fishermen above them.

A catchy title and puns galore adorned my mock up flyer for the event. But what about the speakers? Could I (or should I) make this event balanced? How could I (realising that I have a somewhat biased view of the topic) avoid ‘false balance’, especially when I am not a fisheries expert? I was able to invite three speakers and one chair person; a great number for a small discussion event, but hardly enough for a truly fair and balanced debate – a debate not just on the science of fisheries and marine conservation, but the political, economic and social aspects too. It was clear I needed at least one scientist, but since the discussion was not to be simply about science but about policy as well, I couldn’t just have scientists on the panel. Further considerations were whether those I asked to speak could eloquently handle the job, were prominent enough to lend weight to their arguments, and whether it would be possible to get a diverse panel. As if these considerations weren’t enough, I also had to think carefully about how I wanted the event to run. For example, if a conservation scientist were to speak alone opposite a fisheries representative then the conversation may not have been entirely constructive. It was important to me to try and generate a discussion that left people in a positive frame of mind, or with some good ideas to take away.

In the event, this latter goal took precedence over scientific (or political) balance, especially since those are so difficult to achieve with so few speakers and with my non-expert knowledge of the subject. It was important to me to include panellists and audience members from all the stakeholder groups interested in fishing and marine protection, to have a healthy debate, and to get everyone talking in a friendly atmosphere. Dr. Alasdair Harris, director of the charity Blue Ventures and one of our panellists, summed up the event by saying: “Change is about relationships, and change is about dialogue and understanding perspectives.” We certainly heard some different perspectives during the event, from conservation scientist Professor Calum Roberts advocating for strongly protected marine reserves, fisheries representative Barrie Deas highlighting the difficulties that conservation policies can cause fishermen, to Alasdair’s view that engaging with fishermen is the key to ensuring successful ocean protection and sustainable fisheries. The speakers (and audience members) were able to address each of these perspectives leading to a good degree of balance in the discussion.

A very useful inclusion in this regard was that of having a chairperson (Dr. Helen Scales) who was both trained in media communication and an expert in the scientific field. These skills allowed Helen to use her scientific knowledge to make sure any controversial points were challenged, and her communication experience to drive a positive discussion and engage the audience. Perhaps by using this system more often – with a subject expert acting as chair – we could better avoid situations where non-scientists are able to derail debates by simply denying the science. With science seen as the building block and basis of the discussion, rather than as one side of the debate, we could hope to remove the impact of unrealistic scepticism and focus instead on how we use what we know to inform policy and to drive change.

If you would like to learn more about fishing and marine protection, you can listen to the highlights of the event in this British Library podcast below. The whole event is also available as a video on Youtube, and you can learn about the history of fishing in the British Library science blog. If you would like to hear about future TalkScience events you can check the British Library website or follow @ScienceBL on Twitter.

 

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This blog is written by Cabot Institute member Peter Spooner from the School of Earth Sciences at the University of Bristol.  Peter’s research focuses on deep-sea corals and climate.

The closing date for applying to next year’s round of RCUK internships is Friday 28 August 2015, apply here if you are interested.

Withdrawn: Reflections on the past and future of our seas

Posted on by janet.crompton

On the 23rd of August, and as part of Bristol 2015 European Green Capital, I have the privilege of participating in a conversation about the future of our coastal seas that has been inspired by Luke Jerram’s ethereal and evocative Withdrawn  Project in Leigh Woods.  The conversation will include Luke, but also the esteemed chef, Josh Eggleton  who has championed sustainable food provision and is providing a sustainable fish supper for the event, and my University of Bristol Cabot Institute colleague, Dani Schmidt, who is an expert on the past and current impacts of ocean acidification on marine ecosystems.

My engagement with Withdrawn has been inspired on multiple levels, primarily the enthusiasm of Luke but also arising from my role as Cabot Director and my own research on the oceans. Withdrawn inspires reflection on our dependence on the sea and how we have polluted and depleted it, but also on how we obtain our food and the people at the heart of that industry.

All of these issues are particularly acute for our island nation, ringed by nearly 20,000 kilometres of coastline and culturally and economically dependent on the sea. Beyond our own nation, over 2.6 billion people  need the oceans for their dietary protein, a point driven home when I interviewed Sir David Attenborough on behalf of Cabot (see video below). He passionately referred to the oceans as one of our most vital natural resources. And of course, as Withdrawn reminds us, the oceans have vast cultural and spiritual value. It also reminds us that those oceans and those resources are at profound risk.

I’ve spent over 25 years studying our planet and its oceans. However, my first ocean research expedition did not occur until 1999, and it was a profoundly eye-opening experience. We were exploring the deep sea communities fuelled by methane extruded from the Mediterranean seafloor.  Isolated from light, the ocean floor is a largely barren world, but in parts of the Mediterranean it is interrupted by explosions of colourful life, including tubeworms, bacterial colonies, fields of molluscs and strange and lonely fish, all thriving in exotic mountains of carbonate crusts cut by saline rivers. These are vibrant ecosystems but so far removed from the surface world and light that they instead depend on chemical energy sourced from deep below the bottom of the ocean. And even here we found human detritus, plastic and cans and bottles.

Those were powerful observations, in large part because of their symbolism: our influence on the oceans is pervasive and quite often in ways that are challenging to fully comprehend and often invisible to the eye. These include, for example:

  • The potentially devastating impact of plastic on marine ecosystems, including plastic nanoparticles that are now, for all intents and purposes, ubiquitous.  Of course, pollutants are not limited to plastic – our lab now identifies petroleum-derived hydrocarbons in nearly every ocean sediment we analyse.
  • The decreasing pH of the oceans, due to rising CO2 levels, an acid when dissolved in water. We acidifying the oceans, apparently at a rate faster than at any other time in Earth history, a deeply alarming observation. We are already seeing some consequences of ocean acidification on organisms that make calcium carbonate shells. However, what concerns most scientists is how little we know about the impacts of rapid ocean acidification on marine ecosystems.
  • Ocean warming. A vast amount of the energy that has been trapped in the Earth system by higher greenhouse gas concentrations has been absorbed by the oceans.  Its impact on marine life is only beginning to be documented, but it has been invoked, for example, as an explanation for declines in North Sea fisheries.

And these represent only a few of the chemical and environmental changes we are making to the marine realm. They do not even begin to address the numerous issues associated with our over-exploitation and poor management of our marine resources.

Compounded, these factors pose great risk to the oceans but also to all of us dependent on them. As Cabot Institute Director, I engage with an inspiringly diverse range of environmental scientists, social scientist, engineers, doctors and vets.   And in those conversations, of all the human needs at threat due to environmental change, it is water and food that concern me the most.  And of these, our food provision seems the most wildly unpredictable. The synergistic impact of warmer temperatures, more acidic waters, and more silt-choked coastal waters on a single shellfish species, let alone complex ecosystems such as coral reefs or North Sea food webs, is very difficult to predict. This uncertainty becomes even more pronounced if we factor in nutrient runoff from poorly managed land, eutrophication and ocean anoxia leading to more widespread ‘dead zones’. Or the impact of plastic, hydrocarbon, and anti-biofouling pollutants. The ghost ships of Withdrawn quietly tell the story of how our increased demand and poor management have led to overexploitation of fish stocks, causing an industry to face increasing uncertainty. But they also invoke deeper anxieties about how environmental change and pollution of our seas could devastate our food supply.

But Withdrawn, like other Bristol Green Capital Arts projects and like all inspiring art, does not telegraph a simple message.  It does not shout to ‘bring back local fisherman’ or ‘save our oceans’.  These messages are present but subtly so, and for that both Luke and the National Trust should be celebrated. The boats themselves are captivating and draw you into the fisherman’s efforts; they acknowledge our dependence on the ocean and that we must continue to exploit it. To others they are suggestive of some past catastrophe, a tsunami that has somehow deposited fishing boats in a wildly unanticipated place. And yet to others, they suggest the changing character of seas, seas that once stood 100 m higher than they do today and which almost certainly will do so again if all of our coal and oil is burned into carbon dioxide.

Withdrawn is about all of those things. And consequently, at its deepest level, I think Withdrawn is about change.

Ammonite by Alex Lucas as part of Cabot Institute’s Uncertain World art project.

Geologists have a rather philosophical engagement with the concept of change – on long enough timescales, change is not the exception but the defining character of our planet and life. I should clarify that the aforementioned Mediterranean expedition was my first proper research excursion to the modern seas, but it came long after numerous visits to ancient ones.  In 1993, my PhD co-supervisor Mike Arthur took a group of us to Colorado where we collected samples from sedimentary rocks that had been deposited in the Cretaceous Western Interior Seaway 90 million year ago, a Seaway from a hotter, ice-free world, in which higher oceans had invaded a downflexed central North American basin. That might not seem like a proper marine experience but to a geologist you can reconstruct an ocean in startling clarity from the bold clues preserved in the rock: current flows that tell you the shape of the coastline; fossils that reveal the ecosystem, from cyanobacterial mats on the seafloor to inoceramids  and ammonites  to great marine reptiles in the waters above; and the rocks themselves that reveal a shallow sea in which limestone was deposited across a great platform.

But it was only like this at some times.  The fascinating aspect of these rocks is the complex pattern of sedimentation – from limestones to shales and back again – limestones that were much like the lime cliffs of Lyme Regis, switching in a geological blink of the eye to oil shales similar to those in Kimmeridge Bay, from which, further North and at greater depths and pressures, North Sea oils derive. Limestone. Shale. Limestone. Shale. A pattern repeated hundreds of times.  In the Western Interior Seaway.  Along the Jurassic Coast. Across the globe, from the Tarfaya, Vocontian and Maracaibo basins to the Hatteras Abyss, from Cape Verde to the Levant Platform. Cycles and cycles of astonishingly different rock types – all bundled up in patterns suggesting they were modulated by the ever changing character of Earth’s orbit.  These cycles are change, from a sea with clear waters, little algal growth and ringed with reefs to one fed with nutrients and gorged with algal blooms and stripped of oxygen.

Change is a necessary and inevitable feature of our planet.  And of the human condition.

But we seem incapable of resisting the urge to impose a value judgment for or against change. It is either viewed as a technocratic marvel to be celebrated or a violation against the natural state of the world and to be resisted.  But often, change is conflated with loss.  And there is something of loss in Withdrawn. These are the ‘Ghost Ships’ of Leigh Woods.  Ghosts of a way of life that no longer exists. Ghosts of the animals these boats once hunted.  Ghosts of some past and inexplicable event.

Of course, change will always be about progress vs loss, its value neither solely good nor bad but nonetheless inevitable.  But just because a geologist recognises the inevitability of change does not mean he thinks we should be passive to it. Change will come but should be managed, a significant challenge given its rapid pace over the past 150 years. In fact, one of the main observations of Dani Schmidt’s research is that our current rate of environmental change appears to be essentially unprecedented in Earth history, let alone human experience.

My hope is that Withdrawn has caused people to engage with the concept of change. How do we manage change in the 21st century?  How do we recognise those things that can and should be let go. As one visitor said, ‘We want to resist romanticising the past.’  Conversely, how do we decide what change must be moderated, because its cost is too high?  We can reduce our plastic consumption and waste, and we can enforce more rigorous regulations to stop the pollution of our planet – and we should.  More complicated questions arise from how we manage our dependencies on these precious marine resources, but it is clear that we can eat fish more sustainably, and chefs like Josh Eggleton are showing the way. We can create marine reserves that will not only conserve species but serve as biodiversity hotspots benefitting all of the oceans.

Perhaps most importantly, how do we recognise those things that must be preserved?  When I see the ghost ships of Withdrawn, I feel the poignant loss of our connection with nature and our connection with what it provides. Our food is now produced far away, delivered to sterile supermarkets via ships, trains and lorries; maybe that is necessary on a planet of over 7 billion people but if so, we must strive to preserve our connection to the sea – to our whole planet – understanding what it provides and understanding its limits.

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This blog is by Prof Rich Pancost, Director of the Cabot Institute at the University of Bristol.

Prof Rich Pancost
The final Withdrawn talk at Leigh Woods will be taking place on 23 August 2015 and will feature Cabot Institute scientists, Luke Jerram and chef Josh Eggeleton who will be cooking up a sustainable fish and chip supper for attendees.  This event is sold out.

2050: Sustainable oceans in a changing climate

Posted on by janet.crompton

Which fish species will we be eating in 2050? What will the climate be like, and what will it mean for the productivity of the oceans? And how can we turn fisheries management around so that we harvest sustainably and ensure the livelihoods of fishing communities in the future?

These are three of the questions a diverse group of academics from the Cabot Institute tackled at the inaugural Cabot Writing Day in January. The concept for the event was that invitees from a range of disciplines (in this case marine biologists, lawyers, earth scientists, geographers and NGO representatives) gathered to address a central theme, and in a day produce a position paper:

2050: Sustainable oceans in a changing climate

As you can see we covered a huge amount of ground, gained valuable insights from each other’s disciplines, share personal viewpoints and (deliberately) envisaged a very positive future for fisheries in 2050.

We are now using our discussions to fuel ideas for grant applications, initiate new contact and interaction with industry and policymakers, and potentially develop a TV series.

If you would like help organising a Cabot Writing Day on a subject you think needs attention and which suits the diverse Cabot Institute community, please contact Stephen.Simpson@bristol.ac.uk (Cabot KE Fellow) or Philippa.Bayley@bristol.ac.uk (Cabot Manager) to discuss your ideas…

First 2 months as a Cabot KE Fellow

Posted on by janet.crompton

My name is Steve Simpson and I am a marine biologist in the School of Biological Sciences. My focus for some time has been on how global environmental change influences fish, fisheries and marine ecosystems. At the moment my work in Bristol focuses on the effects of warming on European fisheries and the impacts of anthropogenic noise on marine ecosystems. The first two months of my NERC/Cabot Knowledge Exchange fellowship, which builds on these themes, has presented some fantastic opportunities to explore how my research, and that of all my collaborators in Bristol and beyond, can feed into UK policy and industry.

I was lucky that our study on the effects of warming over the last 30 years on the European fish assemblage came out just as I was starting. This meant I was able to spend a day with the Guardian at Brixham fishing port in Devon talking to trawlermen, wholesalers, fishmongers and restaurateurs about how their catches have been changing. After 3 years of staring at records of over 100 million fish on a computer screen, it was great to hear that their experiences matched up with our analysis. This experience was quickly followed by a week with the International Council for the Exploration of the Seas (ICES) assimilating all the current evidence on influences of climate change on fisheries. I am now developing ideas for a documentary that looks at the science behind changing fisheries and showcases some of the exciting fish we will be eating in abundance in the future. Get ready for John dory and chips…

The week I started my fellowship I was at a meeting at UNESCO in Paris, making plans for an International Year of Ocean Acoustics and discussing ideas for some global experiments on effects of anthropogenic noise in the marine environment. The seas have become much more noisy in the past few decades, due to shipping, oil/gas extraction, windfarm construction and naval activities, and we have to get it right in terms of managing noise without unnecessarily hampering marine industries. The issue of noise has raised some very interesting questions about the precautionary principle, mitigation vs. compensation, and extrapolating findings from small-scale experiments to population-level predictions. I have spent the past few weeks planning a workshop, to be held in Bristol in March next year, where representatives from academia, industry, policy and management will work together to plan the science needed to ensure an environmentally and economically sustainable future for UK waters.

The first 2 months have been hugely exciting and shown me how valuable the Cabot community is for encouraging thinking outside the box, drawing on experience from other groups (e.g. flood risk management informing our future fisheries predictions), and building strong links with the research-end users (aka the real world!). The NERC KE team are doing a fantastic job of building Knowledge Exchange, making the science they fund really deliver, and with Cabot and the RED team in Bristol we’ll be giving training and advice at a KE workshop in January. Watch this space…

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