Personal Reflections on Decolonisation of the Earth Sciences: Am I creating space? Or occupying space?

This commentary is an expansion on my presentation at the 2022 session on Scientific Neocolonialism.


Thank you to EGU for creating the space for this vital conversation, to the organisers and to my fellow speakers, and to all of you for coming.

I would like to start with a statement on positionality.  I have white privilege.  Male privilege.  Cishet privilege. I did grow up in rural poverty; we were farmers and we were poor, and I was a first generation University student. But I did have access to education, and I certainly am no longer working class, no matter how deep the roots may be.  Perhaps of equal importance is my institutional privilege.  I work in a discipline – the geosciences generally and organic geochemistry specifically – that has been built on a legacy of exploitation and extraction; and I work for a relatively stable and secure University that inherited and built – and arguably still builds – its wealth on the back of colonial practices.

As such, I was invited by the organisers to use that privileged position to speak honestly and forthrightly about the historical and ongoing failings of our discipline.  And to acknowledge my own failings.

I do, however, have some ambivalence about participating.  I think it is the obligation of those with privilege – especially those like myself – to do the labour, especially the risky and emotionally taxing labour in talking about difficult topics.  However, I also recognise that in doing so, I am occupying a seat that might have been better filled by someone who lacks my privilege and would benefit from this platform.

Am I creating space? Or occupying space?

I’ll return to this.  And it is an important theme that has pre-occupied me in every role I have taken – from accepting or declining conference invitations to joining NERC’s Science Committee to becoming Head of School . But for now let me say to my colleagues who share my privilege ‘get use to this feeling of discomfort and learn to live with it.’ This discomfort is essential to the decolonial efforts, as is taking any criticism with dignity.


I am not an expert; I am a geochemist.  Like many of us who are struggling with the colonial aspects of the Earth Sciences, I am here as one who has not done as well as I should, wants to do better, and expects all of us – especially the senior leaders of the field – to do the same. However, I have been fortunate enough to learn from colleagues across disciplines. Due to the dearth of expertise in STEM subjects I have often been invited to serve on panels such as these, including the NERC/AHRC Hidden Histories Advisory Group and Bristol’s Decolonising the Curriculum Working Group.  I have also learned from more grass roots radical movements at the University of Bristol, from staff who demand our institution more actively confront its colonial legacies. In all of these, I have tried to be honest about the limitations of my expertise, my genuine desire to learn and my commitment to sharing what I learn from the actual experts.

And the one thing that I have learned is that the legacy of colonialism is pervasive, and that our decolonisation journey will be long and challenging.  And necessary.  @Jairo_I_Funez is a powerful scholar in this space and I hope he does not mind me borrowing a quote of his from Twitter: ‘In practice, the world isn’t divided in silos: colonial, racist, capitalist, & patriarchal silos. These are entangled & distinctly expressed according to geography. Analytically we can try to separate them but in reality they are entangled systems of domination and exploitation.  People seem to really want straightforward manuals for this stuff but that in itself is part of the problem. It isn’t simple or fair because reality isn’t simple or fair.”

So let us talk about the entangled systems of domination and exploitation, in my own career and in our discipline.


I owe a lot to my supervisors and colleagues who helped set me on a strong path during my PhD training.  They taught me to respect other disciplines and expertise, in particular warning me away from scientific hubris and thinking that my new fancy analytical toy can solve the problems that others have struggled with for decades.  Or if we do solve them, to acknowledge that we could not have done so without that previous labour.  Building from that, it is inescapable that we recognise that science is a community, with the vast majority of successes achieved not by a single genius but by a community of scholars who sometimes argue but always centre a constructive and collaborative approach to building knowledge. This is particularly true of the Earth Sciences, where we must collaborate to drill a core through an ice sheet, send a seismometer to Mars, or build a decades long field campaign.

But this inevitably demands that we ask “who is that community?”  Our discipline has been profoundly guilty of helicopter or parasitic science, sometimes cynically so and sometimes with good intentions.  But regardless of the motivations, it excludes scholars from the global south, marginalised groups and indigenous peoples.  Robyn Pickering spoke powerfully about this in her presentation.  So here I want to share that I have made these same mistakes.

You can look through my publication record and find many examples of these: collaborations with New Zealand colleagues that failed to acknowledge the Māori peoples on whose occupied land we worked; collections of samples from exotic locations with which I calibrated palaeoclimate proxies but failed to include local collaborators.  Perhaps the most striking example is my work on arsenic contamination in Cambodian aquifers; this is work that I am very proud of as it helped resolve the biogeochemical mechanisms underpinning As mobilisation.  But our earliest work included no local collaborators, to the detriment of the science, to the detriment of the uptake of our findings, to the detriment of colleagues in Cambodia working on these issues.  [I no longer work in this area, having ‘passed the baton’ to my postdoc who is now at Manchester, but I am glad to see that this group now works in thriving collaboration with Cambodian colleagues.]

There have been times that I have engaged more appropriate practice in terms of collaboration and co-production.  Our palaeoclimate work in Tanzania featured strong collaborations with Tanzanian geoscientists, especially the wonderful Joyce Singano.  In doing so, funding was passed from the UK to Tanzania and prestige was shared, benefitting their careers and their institutions.  This is not theoretical – these decisions have real and immediate consequences and impacts.   So why do we not do it all the time? I have been as guilty as anyone of using the argument that ‘there are no scholars in that area in this country’, but surely that should prompt a number of questions: i) how hard have we really looked; ii) if not, then should we not have a long-term vision of collaboratively building that community; iii) should we not work in an area or a topic if we cannot do it equitably and inclusively?

But I suspect that much of our current neocolonial practices arise from naivety.  We just do not think about these issues.  But naivety is not an excuse for those of who work in institutions of wealth and privilege, are funded by intuitions of wealth and privilege, and work in countries made wealthy by colonial exploitation.  We cannot afford the luxury of being ignorant of our power and influence.

I think that helicopter or parasitic science is the most obvious manifestation of neocolonial practices that persist in our discipline. However, decolonisation is an act of continual reflection, self-critique and learning and that means understanding the complexities in even some superficially strong local collaborations.  I increasingly work with scholars in Panama and Colombia, but often those scholars are part of their own nations’ colonial legacies with their own problematic relationships with indigenous peoples.  Complex legacies of colonialism persist in Africa. Geopolitical complications haunt my collaborations with China, especially in places such as Tibet.

Having said that, I am drifting dangerously close to whataboutery, and I refuse to allow that; I raise these issues not for deflection but to set myself on a path towards ever deeper reflection. The complexity of these issues must not stop action today, and there is nothing preventing us from engaging directly with the colonial sins in our own house.  (For these reasons, Hidden Histories chose to focus solely on British colonialism.)


Decolonisation is about more than diversity and inclusivity, although there is certainly a strong connection between our decolonial and EDI efforts and I do not think one can be legitimate without the other.  Decolonisation is ultimately about agency and power, and addressing that entails challenging the assumptions deeply embedded in our practice and that of our discipline. Our discipline is based on extraction and exploitation.  We pillaged fossils from all over the world, a practice that continues to this day, often in direct violation of the laws of that country.  Our discipline can display an appallingly arrogant and patriarchal view towards the Earth and land, often in direct conflict with those who live on it.   Mary Anning was funded by the enslavement of people – Henry de la Beche, her sponsor and first President of the Palaeontological Association, was an apalling person who acquired great wealth through his slavery inheritance.

Our entire discipline has been instrumental in the exploitation of fossil fuel and mineral resources and the people who live on that land, and we still are.

We must constantly explore and engage with that.  And we certainly must not try to create artificial silos that we pretend can exonerate us from those obligations. I am an organic geochemist, with colleagues, friends and former students who work in the oil and gas sector. I ended my own research collaborations with those industries about 15 years ago – but that was driven by environmental and climate change concerns rather than decolonial ones.  This was a dangerously narrow view that elevated some forms of harm over others.  If we do not include decolonial aspects in our thinking and our science and our practice, we are going to replicate past harms and perpetuate new inequalities under the banner of biodiversity preservation and renewable energy.

It has become quite trendy in our discipline to talk about the necessity of geology – especially economic and resource geology – to a post-fossil fuel future dependent not on oil but copper, cobalt and lithium.  This is true.  But we cannot build a green future on green colonialism (and arguably such an effort, in discarding indigenous knowledge, would be doomed to failure).

Moreover, I cannot simply ignore the deep entanglement of my research practice with colonial and neocolonial histories. My techniques were built by my academic predecessors with industry support.  I can do what I do because of the investment in organic geochemistry fueled by the global exploitation of oil resources (Chevron built first GC-IRMS) . That extends to so may of us, from biostratigraphy to palaeogeographic reconstructions to palaeontology, all built on global extractivism.

I am not saying that we should not work with industry or you have to be anti-capitalist (but many experts do convincingly argue that view).  But I do not see how decolonisation can be compatible with unbridled free marketeering.  It certainly is not compatible with uncritical engagement with any industrial partner.  I leave that to each of you to discuss where those boundaries lie.

And in doing so, we must be quite open-eyed about the fact that most Western Universities, regardless of their taxation status, operate in a pretty damned capitalist and colonial manner themselves. My own University’s logo contains four symbols – a sun, a ship, a horse and a dolphin – each one of those the symbol of a great family in Bristol that built their wealth entirely or in part by the enslavement of people.  That dolphin is the symbol of Edward Colston. But let us not pretend that colonialism is an artefact of the past, ‘Hidden Histories’ alone.  My University, like all UK Universities and many across the West, remains financially dependent on exorbitant fees paid by international students; my salary and my lab and my career are funded by the ongoing extraction of wealth from across the world to the University of Bristol.

We must be awake to these issues and engaged with the harms they have caused – and our complicity with them and continued dependence on them.

‘They are entangled systems of domination and exploitation.’


What can we do?  As with many challenges we face, we must recognise the need for structural change.  In doing so, we must learn, share and act with a certain degree of kindness for ourselves – all of us are somewhat trapped in these colonial structures.  I have colleagues who are seeking research funding from new, less problematic sources who also feel severe institutional pressure to win grants; they feel trapped.  As Head of School, I often feel complicit in enabling their entrapment. Collectively, we must demand structural change.

However, just like tackling racism or climate change, the need for structural change does not exempt us from individual responsibility.  And of course, our individual actions can collectively and joyfully become a movement that drives that structural change.  So here are some suggestions.

Read, listen and learn.  Most of us will not become experts in this topic, but we can all devote time to learning.  I recognise that we are all overworked, but this is an obligation for our discipline.

Have humility for those who do the work, whether they be geoscientists who choose to focus on this area of those outside the discipline.  And then celebrate and reward this work.  Liberate time for our colleagues who do devote time to become experts, and recognise this work in their promotions.  Pay external experts.  Pay marginalised scholars to speak or advise. Pay for their time as we would pay any other consultant.

Accept discomfort and learn from it.  Be thoughtful, continuously thoughtful and with intellectual commitment comparable to how we do the rest of our job.  Be honest with ourselves. So treat yourselves with kindness. But that is no excuse to not challenge and continuously interrogate ourselves and one another.

Most importantly, collaborate and co-produce knowledge. Work with brilliant and inspiring scholars from all over the world. And although this is an important path to reparation, it is also wonderful and joyous.

Finally, build on your learning and experiences to make that structural change.  Demand institutional support – and when you have the privilege to do so, challenge institutional behaviour. Advocate for new policies, from EGU Awards to staff promotions processes to criteria for grants and publications.


Ultimately, however, we must never forget that this is not an academic exercise.  It is part of a wider process of reparation of harm and reconciliation.  It must be a dialogue and it must be tangible. Frantz Fanon wrote: “For a colonized people the most essential value, because the most concrete, is first and foremost the land: the land which will bring them bread and, above all, dignity.”    These conversations are important for our field, but they do not stop colonised people from being exploited, robbed or killed.  Our work must ultimately commit to an agenda that restores wealth, respect and dignity.  And by extension, it must restore stolen agency and power, because these reparations of harm cannot happen using our current structures: “The master’s tools will never dismantle the master’s house.”

Given that end goal, was I right person to contribute? Did I make space or occupy space? On reflection, I think it was it a mistake for me to agree to speak at this session rather than advocating for a speaker from a non-Western nation or from a marginalised group. I hope that I’ve moved our conversation forward, but I am not convinced that I was best suited to use this forum to also achieve reparation.

Instead a speaker from the global south or an  indigenous speaker could have used this opportunity not only to speak honestly and forthrightly about the challenges they face but also use this as a platform to reclaim some of their scientific agency. They could have come to this EGU session, spoken about decolonization but also talked about their science – their ambitions, their findings and the types of collaborations that would strengthen their careers.

I apologise for occupying that space.

This is not white liberal guilt, an emotional response that is often passive and used as an excuse to withdraw. Nor is it performative emoting that continues to centre us at the expense of those who have been harmed. It is a demand that we – I – reflect, listen, learn and improve and to accept that many of us who hold privilege will now have to live in a degree of emotional and intellectual discomfort that will never be resolved.  That is a small price to pay for our many other privileges.

So then, looking towards the next conference or next year, can we all agree that we must do this work and that we do not need someone like me to create this space?

Instead, we should pack this panel with the voices of minoritized and indigenous voices, while also giving them a chance to prominently showcase their science throughout the wider EGU program.

While the rest of us pack this hall to listen to what they have to say.

Some resources:

There are many emerging articles and resources in our discipline; see the following as an example:
Recently, I have been inspired by the writing of @Prof_FSultana, including her fantastic article ‘The Unbearable Heaviness of Climate Coloniality‘.  Here is an example of her writing: “To decolonize thinking/approaches/solutions, we need to address the fertile grounds where colonial & imperial wounds are not minimized but recognized as part of the necessary driving forces of collective liberation. This is particularly true for decolonizing climate justice.  Given the significant insights of feminist, anti-colonial, decolonial & post-colonial scholarships, there is much to be incorporated into empirical & policy-oriented work. Purely technocratic, economistic, or financial solutions will not address the root causes of problems.” And read:

And for a life-enriching immersion in the topic, please consider Kathryn Yusoff’s  ‘A Million Black Anthropocenes or None.’





Is the future of manufacturing local?

I co-authored this with Chris McMahon, Professor of Engineering Design, inspired by his work on how highly adaptable manufacturing processes, capable of operating at small scales (re-distributed manufacturing), can contribute to a sustainable and resilient future.  I find so many aspects of his work fascinating, from the connections to the Industrial Revolution to the argument that many of our societal challenges arise from the disconnection between what we consume and how it is made.  The latter is a theme that resonates across so much of the environmental movement, from the food we consume to our deeper connection to nature. In a world that has become utterly dependent on global supply chains, acutely illustrated by the far-reaching and often unanticipated consequences of Covid, I am not sure if we can restore strictly local manufacturing or even if that is the most efficient way to produce what we need.  But it is a vital question and I have always been inspired by Chris’ knowledge and his wisdom.


The next few years have the potential to be transformative in the history of our society and our planet.  We are faced with numerous choices in how we live our lives, and our decisions could either embed the practices of the last two centuries or empower new paradigms for the production of our food and energy, our buildings and transport systems, our medicine, furniture and appliance, all of those things on which we have grown to depend. It could be a transformation in what we own or borrow, how we use it…. And how we make it.

Bristol is one of the Rockefeller Foundation’s 100 Global Resilient Cities.  Unlike many of the other cities (and somewhat unconventionally), Bristol, the University of Bristol and the Cabot Institute have adopted a holistic definition of resiliency that includes not just adaption to future change but also the contemporary behaviour that minimises the chances of future shocks.  Recognising that, the launch of the Bristol 2015 European Green Capital year focused on the need to bridge the gap between our resource intensive and environmentally harmful current behaviour and a more sustainable – and resilient – future.

This combination is key.  We know that our non-sustainable behaviour will bring about dangerous climate change and resource stress. But we are also obtaining a sharper understanding of the limits of our knowledge. Unfortunately, our behaviour is not just threatening the security of our food, water and energy but is inducing a profound uncertainty in our ability to forecast and adapt to future change.  Not only does such radical uncertainty demand mitigative rather than adaptive action but, where we fall short or the damage has already been done, it will require an equally radical emphasis on resiliency.

Part of Bristol’s path to achieving these goals of sustainability and resiliency is localism, including local production of food and energy, exemplified by the recent launch of a municipally-owned energy company but also community-owned energy and food cooperatives.   Localism can only go so far in our highly interconnected and interdependent world, but it is undeniably one of Bristol’s strongest tools in empowering local communities and driving its own sustainability agenda while making us more resilient to external factors.  But why stop at food and energy?

Manufacturing has undergone a suite of radical transformations over the past decade, the potential of which are only now being harnessed across a range of manufacturing scales from high-value (such as Bristol’s aerospace industry) to SMEs and community groups.  Crudely put, the options for the manufacturer have traditionally been limited to moulding things, bashing things into shape, cutting things and sticking things together.  New technologies now allow those methods to be downscaled and locally owned. Other technologies, enabled by the exponential growth of computer power, are changing the manufacturing framework for example by allowing complex shapes to be made layer-by-layer through additive manufacturing.

Crucially, these new technologies represent highly adaptable manufacturing processes capable of operating at small scales.  This offers new possibilities with respect to where and how design, manufacture and services can and should be carried out to achieve the most appropriate mix of capability and employment but also to minimise environmental costs and to ensure resilience of provision.  In short, manufacturing may now be able to be re-distributed away from massive factories and global supply chains back into local networks, small workshops or even homes. This has brought about local empowerment across the globe as exemplified by the Maker movement and locally in initiatives such as Bristol Hackspace.  These technologies and social movements are synergistic as localised manufacturing not only brings about local empowerment but fosters sustainable behaviour by enabling the remanufacturing and upcycling that are characteristic of the circular economy.

There are limits, however, to the reach of these new approaches if they remain dependent on traditional manufacturing organisations and systems into which we are locked by the technological choices made in two centuries of fossil-fuel abundance.  As well as the technologies and processes that we use, a better understanding of how to organise and manage manufacturing systems and of their relationship with our infrastructure and business processes is central to the concept of re-distributed manufacturing and its proliferation.  It requires not only local production but a fundamental rethinking of the entire manufacturing system.

Looking forward, we must explore a whole range of issues from diverse disciplinary perspectives, bringing together experts in manufacturing, design, logistics, operations management, infrastructure, engineering systems, economics, geographical sciences, mathematical modelling and beyond.  In particular, we must examine the potential impact of such re-distributed manufacturing at the scale of the city and its hinterland, centering not just resilience and sustainability but equity and inclusion.


It seems entirely appropriate that Bristol and the SW of England assume a prominent leadership role in this endeavour.  In many ways, it is the intellectual and spiritual home of the industrial use of fossil fuels, responsible for unprecedented growth and prosperity but also setting us on a path of unsustainable resource exploitation.  Thomas Newcomen from South Devon produced arguably the first practical steam engine, leading to the use of fossil fuels in mining and eventually industry; in the late 1700s, coal-powered steam energy was probably more extensively used in SW England than anywhere in the world.  Continuing this legacy, Richard Trevithick from Cornwall developed high pressure steam engines which allowed the use of steam (and thus fossil fuels) for transportation, and of course Brunel’s SS Great Western, built in Bristol, was the first vehicle explicitly designed to use fossil fuel for intercontinental travel.

But that legacy is not limited to energy production.  Abraham Darby, who pioneered the use of coke for smelting iron in Coalbrookdale, i.e. the use of fossil fuels for material production, had worked at a foundry in Bristol and was funded by the Goldney Family, among others.  He married fossil fuels to the production of materials and manufactured goods.

These are reasons for optimism not guilt.  This part of the world played a crucial role in establishing the energy economy that has powered our world.  On the back of that innovation and economic growth have come medical advances, the exploration of our solar system and an interconnected society.  That same creative and innovative spirit can be harnessed again.  And these approaches need not be limited to energy and materials but also healthcare and the digital economy. The movement is already in place, exemplified by the more than 800 organisations in the Bristol Green Capital Partnership.  It is receiving unprecedented support from both Universities of this city.  This new project is only one small part of that trend but it illustrates a new enthusiasm for partnership and transformative change and to study the next generation of solutions rather than be mired in incremental gains to existing technology.

The 50th Anniversary of the Organic Geochemistry Gordon Research Conference

In 1970, some of the world’s leading research held the first Organic Geochemistry GRC.  It was not the first organic geochemistry conference, and our field traces its origins to some 20 years earlier – when Alfred Treibs showed the structural link between biologically produced chlorophylls and hemes and their diagenetic products in rocks and oils.  In doing so, he showed that organic matter in the sedimentary record was nearly entirely of original biological origin – albeit significantly altered by diagenetic and catagenetic processes.  This then was the platform for a diverse discipline that explored topics ranging from the exploration of life on the moon and other planets, the fingerprinting and discovery of fossil fuel deposits (as well as the fingerprinting of fossil fuel contamination), the probing of critical Earth system processes, and the reconstruction of the past – in historical and archaeological contexts to recent climates to deep time and even the early history of life.

I was fortunate to be chosen by my colleagues to chair the 2020 Organic Geochemistry GRC which would have marked its 50th Anniversary.  We had a fantastic lineup of speakers – from diverse backgrounds, international, and with interests ranging from the origins of biosynthesis to the fate of organic matter in polar regions to the structure of membranes (many of the best biomarker tracers for past climates are membrane lipids). Unfortunately, that was cancelled due to Covid.



The original 1970 GRC Attendees.
A larger and much more diverse cohort in 2018. And full of wonderful colleagues spanning several generations of organic geochemistry. But like all of the geosciences, our discipline still has some work to do to be truly racially and ethnically diverse.

Instead we marked it virtually, sharing photos and memories.  This fantastic figure by Keith Kvenvolden captures the origins of the GRC, its attendees and themes.  It has changed in many ways but the seeds of everything we do now – the discovery of new biological and geological materials, the centrality of analytical innovation, the ambition to look at *anything* – were already present.



For the past 20 years or so, the Organic Geochemistry GRC has been hosted at Holderness School in New Hampshire.  We miss you.  But Roger Summons was passing through and took some photos…. we are there in spirit.



And some pictures from the past.  They would not be complete without table football! Who are these fierce competitors.  And where are their shoes?


And some photos courtesy of Roger!





Also courtesy of Roger is a photo of the iconic Thursday night lobster dinner.


Cait Witkowski shared this great photo of the NIOZ group (past and present)


And others shared photos of meeting up (socially distanced) in other ways!

Flo and Nadine are evidently still working on that asphate seep paper from Nadine’s masters research!

One of the key events at the GRC is the awarding of the Treibs Medal (by the Organic Geochemistry Division of the Geochemical Society). This year, the very worthy winner is my friend and colleague Kai-Uwe Hinrichs of MARUM. Congratulations, Kai. It is hard to imagine a more deserving winner.

Kai’s research group (and one visitor!)

Last year’s winner was Sylvie DeRenne (awarded at IMOG in 2019) and the previous GRC Awardee was Stefan Schouten.  Here is a history of Dutch diagenesis that… I guess led to his formation?


Previous recent winners include Kate Freeman, Marilyn Fogel and Pat Hatcher. But of course Steve Larter had to mark his award with a song… which he forced all of the 2014 Scientific Committee to sing.  I reluctantly share this:

Also announced during our virtual GRC: Three members of the MIT Group started an organic geochemistry podcast!  Great initiative by @FatimagulHusain@angelshale, and @wizardofdrozd You can check it out here!

And of course, Gordon Inglis also hosted the second Biomarker World Cup on Twitter – a chance to learn about biomarkers and banter!  The brackets and results are below… and if you follow some of the links, you will be able to learn about these amazing compounds.  And if you follow this link to the twitter thread, you can see the extensive associated banter (including reversals, betrayals, friendships torn asunder)!

From Gordon: To celebrate the 50th Anniversary of the first Organic Geochemistry Gordon Research Conference (GRC), the ‘Biomarker World Cup’ has returned for its 2nd edition! It will feature 16 biomarkers and conclude this weekend. Who will win? Only you can decide!! #50YrsOrgGeochemGRC

Group A, Team 1: 𝘯-alkanes. Veteran biomarkers and reigning champions. Derived from epicuticular wax of terrestrial plants, they are nature’s ultimate waterproofing. Insights into vegetation, C3 vs C4 photosynthesis, rainfall and diagenesis (). Versatile. (

Group A, Team 2: Polycyclic Aromatic Hydrocarbons (PAHs). Volatile compounds produced by the incomplete combustion of organics. Usually interpreted to indicate changes in fire occurrence (e.g. Karp et al., 2018; ). Inferno. (

Group A, Team 3: Ladderanes. Made their debut at the GRC in 2002. Geoff Eglinton took Jan de Leeuw aside and asked if they were a joke (!). Biomarkers for anaerobic ammonium-oxidizing bacteria (e.g. ). Modern Art. (

Group A, Team 4: 2,6,15,19-tetramethylicosane (TMI). Perhaps the “…rarest biomarker in the world” (@rpancost, pers. comm). Archaeal origin. An acyclic isoprenoid only found during mid-Cretaceous Oceanic Anoxic Events (e.g. OEA1b; ). Underdogs. (

Vote now for the winner of Group A! Only one team will qualify to the semi-finals.

This was contentious with the upstart Ladderanes challenging the iconic n-alkanes. It prompted some discussion on Twitter:


Wow! The holders (n-alkanes) are knocked out in the first round! Absolute scenes. Instead, the world’s weirdest biomarker (ladderanes) progress to the semi-final. Who will join them? Vote now!! #50YrsOrgGeochemGRC

Group B, Team 1: Crenarchaeol. A funky molecule with a unique structure. Specific to the phylum Thaumarchaeota. Not good enough for TEX86, but a rising star in the paleobarometry community (see @sarahjhurley et al; ). Fluid. (

Group B, Team 2: Alkenones. Sea surface temperature proxy. CO₂ proxy. Algal productivity proxy. Salinity proxy (e.g. Gabriella Weiss et al ). Is there anything it can’t do!? Discovered in the late 1970s, but still going strong. Legendary. (

Group B, Team 3: long-chain diols. Another oldie, originally discovered in the early 1980s. Multiple sources (diatoms, algae) but new interest as a proxy for input of riverine organic matter (e.g. Julie Lattaud et al., ). Potential. (

Group B, Team 4: 3-methylhopanoids. Once attributed to aerobic methanotrophs. Used to study Neoarchean aerobiosis, but can be produced by other bacteria. Methylation may aide survival under nutrient limited conditions (@PaulaWelander & Summons; ). Diverse. (

Vote now! Only one team will progress!! #50YrsOrgGeochemGRC

A game of two halves. After leading for 12 hours, alkenones faded away in the second half. They will be really disappointed with that performance. Congratulations to crenarchaeol who progress to the semi finals. Next up: Group C!

Group C, Team 1: branched GDGTs. Who produces them? Who cares! First discovered in a Dutch peat, now found just about anywhere. Can help distinguish OM sources. Routinely employed as continental temperature and pH proxies (). Rising star. (

Group C, Team 2: 24-isopropylcholestane. Unusual molecule found in Precambrian rocks (~650 to 540 Ma). Perhaps the oldest evidence for complex animal life () but may also be produced by unicellular organisms. (). Controversial. (…) (

Group C, Team 3: Porphyrins. Discovered and described by Alfred Treibs (“the father of organic geochemistry”) in 1936. Derived from chlorophylls and helped to confirm the biological origin of petroleum. Now used to provide insights into N-cycling (e.g. ). (

Group C, Team 4: Highly branched isoprenoids. Notable for the distinctive “T-branch” in their carbon skeleton. Used to explore the rise of diatoms during the Phanerozoic (e.g. ). Also a useful sea ice proxy. Utility. ( Vote now! Only one team will progress!! #50YrsOrgGeochemGRC

Porphyrins were a formidable force back in the 1980’s. However, they seem to have lost their enchantment as well as supremacy. The golden era is over. Instead, branched GDGTs progress! Now onto Group D

Group D, Team 1: Isorenieratane. Light-harvesting pigment derived from photosynthetic green sulphur bacteria. These bugs like sunshine and hydrogen sulfide but hate oxygen. Regarded as key evidence for euxinia in the geological record (). Indicative. (

Group D, Team 2: Phytane. Diagenetic product of chlorophyll (…but other sources likely). Easy to measure using gas chromatography. Pristane/phytane often used as redox indicator. Renewed promise in recent years as a paleo-CO2 proxy (). Revitalised. (

Group D, Team 3: Archaeol. Abundant in methane-rich settings. Ridiculously low carbon isotope values (-100 per mil) provided early evidence for the involvement of archaea in anaerobic oxidation of methane ( & ). Extreme. ( (

Group D, Team 4: Heterocyst Glycolipids. Biomarkers for nitrogen-fixing cyanobacteria (…move aside 2-methylhopanoids!). Remarkably well preserved in ancient sediments and can provide unique insights into microbial ecology (). Potential. ( Vote now! Only one team will progress!! #50YrsOrgGeochemGRC

That was the closest race I have EVER seen. Nailbiting. Congratulations to phytane! Now onto the semi-finals

Semi Final 1: Ladderanes vs branched GDGTs. Do you prefer cyclobutane or cyclopentane rings? Only YOU can decide! #50YrsOrgGeochemGRC

Branched GDGTs win!

Semi-final 2: Crenarchaeol vs phytane. Liquid chromatography vs gas chromatography. The winner will face brGDGTs in the final. You have 24 hours to decide!! #50YrsOrgGeochemGRC

Its been a long season for phytane and they looked increasingly fatigued as the game wore on. Crenarchaeol, with its superior mass-to-charge ratio, took full advantage. A big win for the big molecule. Now onto the long-awaited final

The final: branched GDGTs vs Crenarchaeol. Bacteria vs Archaea. Terrestrial vs Marine. It’s the ‘Battle of the GDGTs’. Who will win? You have 48 hours (!) to decide! #50YrsOrgGeochemGRC

It is all over! Crenarchaeol win the 2020 Biomarker World Cup. A deserved victory. Branched GDGTs are runners-up for the second World Cup in a row. Ouch!

Thanks to everyone who participated over the last week. It was a blast! #50YrsOrgGeochemGRC @rpancost

Congratulations to crenarchaeol but also to Laura Villanueva who clearly went all out for the cause, appealing to marine deities (and the entire Archaea research community) to support the cause.  Image


The Origin of the Uncertain World Art

Everyone, gather round! I want to tell you how the marvelous @LucasAntics Park Row artwork came to pass!
In 2014, Bristol was preparing to be the European Green Capital in 2015. Many great projects were envisioned, including collaborations with Bristol’s outstanding artists, like @lukejerram who created Withdrawn: and many curated by @FestivalofIdeas.
It had been about 50 years since the publication of J.G. Ballard’s iconic disaster novels, The Drowned World, The Burning World and my favourite, the surreal and biologically disturbing The Crystal World. Consequently, ideas were brainstormed around these.Image
These did not happen. That was probably for the best as no matter how brilliant and perceptive Ballard is, these novels have a very white, male, colonial perspective. Not ideal for our diverse city. But it simulated conversations. As @cabotinstitute Director, I was asked: “What will be the nature of our future world, under climate change?” And my answer was ‘An Uncertain World.’ We can predict warming & rainfall, but we are creating a world beyond all human experience. This was informed by our work on past climates. It has been about 3 million years since the Earth last had so much carbon dioxide in its atmosphere. And the rate of increase is nearly unprecedented in Earth history. For more on these, see other Uncertain World blog pages:……

Reconstruction of climate over the past 60 million years. The d18O values show the long-term cooling of the Earth, compared to the lower figure showing the similar long-term decline of PCO2 to levels of 270 ppm… Before the Anthropocene increase to 417 ppm.

And hence the Uncertain World.

And to visualise that, we thought it would be fascinating to juxtapose our city – specifically St Werburgh’s – with it’s ancient Mesozoic past. Flooded and thriving with plesiosaurs, ammonites and icthyosaurs. And who better than @LucasAntics?Image

And so Alex created these! Thanks to @ERC_Research and @NERCscience for helping to fund it!Image
And we all loved them so much, that we got permission to paint them on the side of the @BristolUni Drama Building!

Learn more about Alex’s great work at her website: Visit. It. Now. And be filled with joy.

To read about what we learned about the challenges of living with Uncertainty, more relevant now than ever, go here:… 

Fun fact: @DrHeatherBuss and I have all of the original artwork in our house! Including these drawings of a soon to be flooded St Werburgh’s. Views toward St Werburgh’s City Farm and Graffiti Tunnel!

AND…. all* of the original drawings of the menagerie of critters, not all of whom made it into the art!

*All but one that we gave away to a young fan of Mary Anning!Image

Thank you for listening. I thank Alex and others for inspiring me to use some quirkiness, wonder and silliness as a gateway to the very serious conversations we must have about climate change and biodiversity loss. 💚 

Postscript: The Green Capital Year was amazing. I loved it our collaborations with artists, engaged citizen movements and innovators. But it was not as inclusive as it should have been. And from that lesson arose the Green and Black Ambassadors!


Bristol Clear – My Life in Science

Bristol Clear is a University of Bristol initiative to build support, create voice and connect Early Career Researchers.  One of its activities is sharing the stories of more senior researchers, stories that are honest about the challenges many of us have faced, the hurdles we have overcome, the love for research or teaching that keeps us going, and the sacrifices we have made. Academia is a wonderful career; but we lie to ourselves and the next generation if we are not open about its challenges and demands.  Here is my (abbreviated) story.

What I do:

I study how the Earth works as a system, how all of the biological, climatic, geological and chemical components interact today and how they interacted in the past.  I was also Director of the Cabot Institute, which was a chance to not only work across disciplines and research environmental problems but to support a wide range of academics and partners studying solutions to those problems.  Currently, as Head of School, I have all sorts of new obligations but am particularly enjoying connecting to a new group of amazing students.

Why Academia?:

How I ended up in academia and even higher education is a complicated question.  Part of it was because I was good at it: I was smart, good at exams and course work and got good grades.  Part of it was because I loved it; I followed every Shuttle launch and was glued to the television as Voyager 1 and 2 whipped past Jupiter and Saturn. And part of it was because it could get me out of poverty.  I try not to overly mythologise growing up on a small dairy farm in Ohio, but I did love it.  I loved working outside and working with my family.  But I also hated the machinery, the brutality of it; the ceaselessness of farm life, no matter if you are sick or if there is a heat wave or a blizzard; the uncertainty, the worry, the continuous worry about the weather and the bills. It seemed like we were always talking about bills – for the farm equipment, the mortgage, the water and electricity, the dentist and the doctor….

So university always seemed inevitable.  I could go. I wanted to go.  I needed to go.

Our dairy farm in Ohio – photo taken just before we sold the farm (which is why there are no cows or horses)


College was fantastic.  I loved the intellectual freedom and the variety.  My god, especially the variety.  Then and now, that has to be one of the most amazing things about academia.  Every day is different.  Every hour is different.  I had come to college to study astrophysics.  Or political science. Or literature.  In the end, I studied geology. I loved it all.  [During the summer after my Freshman Year, with discussions of environmental crises beginning to trouble the news, with my family’s farm seen in a new light after being away for a year, and with my interest in both science and politics growing, I decided I would merge my interests.  I would study geology and then go on to Law School and become an environmental lawyer.]

However, it also took a long and awkward time for me to fit in, this farm boy at a big university, first generation, working class, a bit of a country hick. I was anxious about belonging in this different world. I was anxious about my grades – I’d lose my scholarships if my GPA dropped below 3.0.  I was anxious about my family, who had to give up farming when my brother and I went to college because they just did not have the labour to keep it going.  I was anxious about money – money to join activities and money to even pay tuition (I could not work during the summer after my 3rd year because I was at Geology field camp; thankfully I got a last minute alumni scholarship).  But I did not know I was anxious.  There was no time to contemplate that.  And in any case, where I come from, you don’t get anxious; you fight.

I had support, but I wish that support had been more aware.  I wish that they could have seen past my good grades and enthusiasm for scholarship and seen the kid who was suffering from anger and anxiety. I wish they could have seen that my bravado was a lie and that my cuts and bruises were a sign of someone using sports and contests to inflict self-harm. I wish that I had been more self-aware.  I wish that I had realised that some of my actions were signs of self-doubt, fear of appearing foolish or uncool, and anger at being mocked and poor and unable to afford what others could.

But friends – even those who inadvertently made me feel that way – supported me. Lecturers championed me.  And helped me financially.  They paid me on internships and work study and once, when money was really tight, even to paint their house. And they taught me with passion and love for the subject. They gave me good grades; and when I was complacent, they gave me my first bad grades.  They were patient and then impatient and patient again.  And finally, they gave me advice, support and wisdom.  I graduated top in my class and won a PhD Fellowship to the Department of Geosciences at Penn State.

There are two stories that explain why I went to graduate school rather than becoming an environmental lawyer, and they are both true in their own way.  In the first, Geology stole me from that path by showing me a stunning and beautiful world: I found my first fossil in the Cleveland Shale in Rocky River Park; I felt my first sense of wonder at geological time in an outcrop teeming with Ordovician brachiopods and trilobites in the Cincinnati Arch; I marvelled at the forces that had shaped the Appalachian Mountains. And then, in the summer of 1991, my field project in the Wind River Mountains of Wyoming, one of the most beautiful parts of the world, revealed to me 500 million years of Earth history over the course of an exhausting, exhilarating, sweaty, blistering, eye-opening summer.

And the second story? I would have had to go further into debt to attend Law School, whereas graduate school would pay me a stipend. That’s all. Your choices are never entirely your own.

My career path / the big decisions:

 I loved graduate school, but the first two years were a battle.  A battle to flip from being a straight-A student who had excelled at learning and tests, who could solve problems and equations to a scientist who could conceive new ideas, new questions and design the experiments to test them.  I had a brilliant supervisor – Kate Freeman – but also a network of mentors and advisers across the department who tolerated my fumbling journey, pushed me at times, and let me make a few astonishingly poor decisions – but not too poor. I was allowed to learn and to fail and learn again.  And it was frustrating and it was amazing and always always always interesting.

And thrilling.  Nothing is as thrilling as discovering something, whether it be something fundamentally new, like a new biogeochemical pathway or a new compound, or even just being the first person in the world to analyse a particular rock.  And related to that is the thrill of having an idea, nursing it, testing it, patiently, rigorously and then proving it right – bringing a new sense of understanding into the world.

 So clearly I was hooked.  I would finish my PhD.  Get a post-doc. And then get an academic job. And I am still hooked, almost like a drug, addicted to those thrills, those moments of discovery, those moments when you know something – even if it is just a small something – about the universe that no one else does. And then sharing that with the world.

But addictions require sacrifice.  The post-doc opportunity was in the Netherlands.  I’d only been out of the country once before and no one else in my family even owned passports. You don’t travel when you have no money.  You don’t travel when you own a dairy farm. My parents always wanted the best for me, they wanted me to go to college, they wanted me to excel and to be successful; but at heart, we were still a farm family from Ohio and they never thought I would move that far away.

But I did.  And then I made that permanent when I moved to Bristol.  I have no regrets about those moves; I love this University, my School, my discipline, this city and my academic career.  But it would be a lie to say that this career does not demand sacrifices from us.  It would be a lie to say that this move was not hard and painful, that it has not had consequences, that family connections are more fragile and that some have been lost.  My parents cannot fly, they still do not have passports; they have never seen my house or my home or my city.

My advice to my younger self:

 I’d tell him that he could ask for help. I’d tell this kid, who was proud of his working class background but who had also buried some anxiety and fear and anger,  that he could ask for help.  That it is not a sign of weakness.

I’d tell him to stay true to who he is; it will have consequences but you cannot betray who you are.  Academia is less prone to class prejudices than other disciplines, but they do persist.  I always felt out of place at the wine tastings and expected cultural literacy.  I still have some dodgy teeth because we could not get dental care when I was a teenager. And even now, despite a great deal of success, I can still be told that I ‘lack gravitas’…

And I’d tell him that we always have choices. They can come with financial or emotional risk, but we do have them.  You can embrace the addiction of academic life or you can kick the habit if the thrill is not worth the sacrifice. I think he would have made all of the same decisions, but I wish he had known that the world is vast and full of options.  I would tell him that he will have an amazing life no matter what choices he makes as long as he remains true to himself and his values.

This was originally posted on Bristol Clear Blogs.

Tackling climate change is fundamentally a question of justice

This is one of my very first blogs, co-authored with friend and colleague Patricia Lucas.  It was written for Business Fights Poverty (hence the questions at the end), and it stakes out the central themes of my research then and now: that the biggest challenge climate change poses is a world with profoundly greater uncertainty – and with that, confusion, opportunism and victimisation; and that it is the poor and vulnerable who will bear these risks.
Tackling climate change is fundamentally about justice.  About fairness. About equality.
In September 2013, the IPCC published the Fifth Annual Report on the Physical Basis of Climate Change.  It devotes little attention to the human and ecological impacts of global environmental and climatic change, topics that will be addressed by working group reports released in early 2014 .  Nonetheless, the trajectory of climate and other environmental changes and their implicit impacts on society are stark. Despite numerous treaties and efforts at mitigation, concentrations of carbon dioxide and other greenhouse gases continue to increase, and at greater rather than diminished rates. If those rates continue they will result in global warming of 3 to 5.5°C by 2100. This in turn, will result in dramatic changes to the global hydrological cycle, including both more evaporation and more rainfall.
A More Uncertain Climate
Flood; photo by Paul Bates

The results will be a more hostile climate for many as land can become either drier or more flood-prone or both, changes exacerbated in coastal areas by sea level rise.  Freshwater supply will also be affected by the forecast changes in climate. The quantity of water flowing in glacier or snow-melt fed river basins will change, affecting around a sixth of the world’s population[i], while coastal freshwater will be contaminated with saline water[ii]. Areas of the Mediterranean[iii], Western USA[iv], Southern Africa[v] and North Western Brazil[vi] are projected to face decreased availability of freshwater.

Key to understanding who will be affected is our ability to predict changes in rainfall, seasonality, and temperature at a regional scale.  However, regional climatic predictions are the most challenging and least certain, especially with respect to the nature and amount of rainfall. For vast parts of the world, including much of South America, Africa and SE Asia, it is unclear whether climate change will bring about wetter or drier conditions. Thus, uncertainty will become the norm: uncertainty in rainfall; uncertainty in weather extremes and seasonality; and most importantly, uncertainty in water resources.

Those combined effects lead to an additional and perhaps the most profound uncertainty for the latter half of the 21st century: uncertainty in food production and access. In the absence of other factors, climate uncertainty and more common extreme events will compromise agriculture at all scales, yielding increased food prices and increased volatility in markets.

Impacts on the Poor

Although the human impacts of climate change will be diverse, their effects will be worst for the most impoverished and, by extension, least resilient population groups.  The UN reports that climate change could “increase global malnutrition by up to 25% by 2080.”  And all of this occurs against a backdrop in which access to food is already a challenge for the poorest of the world already a challenge for the poorest of the world [p5], a situation exacerbated by the global financial crash.These risks to the poorest result from a lack of resources to mitigate harm, lack of power to protect resources, and the global competition for resources.
Those who lack the financial resources to migrate or build more hazard-resistant homes will suffer most from extreme events, as has been sharply illustrated by those suffering most in the aftermath of Typhoon Haiyan.  Those who can least afford to dig deeper wells into more ancient aquifers as water resources diminish will go thirsty.  Subsistence farmers – and those dependent on them – are less resistant to climate shocks (desertification) and adverse weather events (flooding) than commercial farmers.
Land ownership for the poorest is often tenuous, and displacement from land a serious problem for many.  Previous switches to biofuels have led to land competition, resulting in both loss of land to subsistence [p6]  farmers, and diversion of commercial production leading to shortages [p7]  and increased food prices. Within communities, these effects are not evenly spread as marginalised groups, such as women, are the least likely to hold land tenure [p8] .  Similarly, there is increased competition for water [p9]  between peoples, but also between water for industry (including agriculture) and water for drinking. When water is scarce, pollution of fresh water is common, and governance is weak, the poorest are likely to lose out.
Food security comes in many forms, reflecting not just climate and environment but culture, politics and other social constructs. Image by Mammal Research Unit, University of Bristol

Food competition will most likely be exacerbated by other factors: rising demand from a rapidly expanding population and a growing demand for meat from a global ‘middle class’; the increased economic divide between post-industrial and developing nations; the ongoing depletion of soil nutrients and associated impacts on the nutritional value of our food.  The combination of these factors will result in profound impacts on food security. Who decides what gets grown? Who can afford it in the context of global markets and the loss of agricultural land? The poorest members of even the wealthiest societies are the most vulnerable to dramatic and unpredictable changes in food costs[p10] .

‘Wicked Problems’

These issues yield a profoundly challenging ethical issue: the wealthy who are most responsible for anthropogenic climate change, via the greatest material consumption and energy demand, have the greatest resilience to food market fluctuations and the greatest means for avoiding their most deleterious impacts.  Therefore, these issues challenge all governments to dramatically and swiftly act to decrease greenhouse gas emissions and mitigate the associated climate change.
Unfortunately, many proposed mitigation strategies could also have negative consequences for food prices and availability. Increasing energy prices, such as those brought about by a carbon tax, will be passed onto food prices.  Genetically modified foods could be essential to feeding a growing population, and we would urge that future efforts expand to incorporate a greater degree of climate resilience in crops; however, the patents on those crops can make them financially inaccessible to the poorest nations or build critical dependencies.
Although sustainable agriculture and crops might reduce the impact of climate change and uncertainty in some countries, these solutions can be deleterious for the poorest.  They are more likely to live in regions and areas most negatively affected by climate change, most likely to be relying on subsistence/small scale agriculture and least likely to have access to the global market as consumers.  In other words, a stable global market will be of little direct benefit to them; in fact, most of these populations are likely to face competition for land/water use from globalised markets (for biofuels or commercial farming).  In short, what builds food resilience in one nation might be exposing the most economically vulnerable in another.
In fact, when properly mobilised for the benefit of the community, access to new energy sources – even if in the form of fossil fuels – can be transformative and facilitate the economic growth needed to access increasingly globalised food markets [p12].    Domestic access to gas reduces the need to collect wood for fires, reducing deforestation, improving air quality, and freeing up time for communities to address other development needs.
This is not an argument against mitigation of climate change, far from it!  We must continuously and aggressively try to minimise the harm that climate change will cause.  But it does need to be balanced against human development needs, and this represents one of the world’s most profound challenges. In some circles, we consider this a ‘wicked’ problem: a problem that has multiple causes, probably in interaction, and where information is incomplete, such that proposed solutions might be incomplete, contradictory, complex and work across multiple causes in complex systems.
Challenges and Opportunities

Wicked problems are not intractable, however, and previous studies of land use for biofuels provide clues as to how a complex solution could be more sustainable for all; well planned switches to biofuels which consider local custom in land tenure can provide more land for agriculture, and reduce deforestation pressure.

In such situations, we argue, solutions which focus on halting or slowing climate change alone, and then coping with the business and development problems that they might create answer the wrong question.  Our challenge to the business (and academic) community, then, is to engage with some wicked questions:

  • What are the business opportunities in improving the social and physical environment?
  • Can the global agricultural system be a single resilient network, rather than a competition?
  • What technology or innovation is needed to support a resilient food network?
  • How can innovative solutions to these challenges generate local income, allowing reinvestment in education and development?
These are difficult questions but they also represent opportunities for development and growth in poor communities.  A world with increasing environmental uncertainty is a challenge for both businesses and vulnerable communities.  But it could also be a shared opportunity for growth and development: to innovate and identify new solutions, to co-invest in local resilience and risk reduction, and to share the growth that arises from more stable communities.

[i] Z Kundzewicz, L Mata, N Arnell, P Doll, P Kabat, K Jimenez, K Miller, T Oki, Z Sen & I Shiklomanov, Freshwater Resources and their Manegemtn. Climate Change 2007: Impacts, Adaption and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press2007
[ii] R Buddemeier, S Smith, S Swaaney & C Crossland, The Role of the Coastal Ocean in the Disturbed and Undisturbed Nutrient and Carbon Cycles,  LOICZ Reports and Studies Series2002, 84
[iii] P Etchevers, C Golaz, F Habets & J Noilhan, Impact of a Climate Change on the Rhone River Catchment Hydrology,Journal of Geophysical Research2002, 4293
[iv] J Kim, T Kim, R Arritt & N Miller, Impacts of Increased CO2 on the Hydroclimate of the Western United States, Journal of Climate2002, 1926
[v] M Hulme, R Doherty & T Ngara, African Climate Change, Climate Research2001, 145
[vi] J Christensen, B Hewitson, A Busuioc, A Chen, X Gao, I Held, R Jones, R Kolli, W Kwon, R Laprise, V Magana Rueda, L Mearns, C Menendez, J Raisanen, A Rinke, A Sarr & P Whetton, Regional Climate Change, The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change,2007, 847
This blog is written by Prof Rich Pancost, Director of the Cabot Institute and Dr Patricia Lucas, School for Policy Studies, both at University of Bristol.
Dr Patricia Lucas
Prof Rich Pancost
This blog has kindly been reproduced from the Business Fights Poverty blog.

Ancient global warming caused extreme rainfall events

Some reflections by my co-authors and me on our recent paper in Earth and Planetary Science Letters, showing that ancient global warming was associated with an increase in the number of extreme rainfall events and this had a profound impact on the land and coastal seas.

The Palaeocene-Eocene Thermal Maximum (PETM), which occurred about 56 Million years ago, is of great interest to climate scientists because it represents a relatively rapid global warming event, with some similarities to the human-induced warming of today.  Although there have been many investigations of how much the Earth warmed at the PETM (about 5 to 8C), there have been relatively few studies of how that changed the hydrological cycle.  This newly published work shows that rainfall increased in some places and decreased in others, according to expectations, but that much of the world experienced more intense and episodic (or ‘flashy’) rainfall events.

Lead author Matt Carmichael (School of Chemistry and School of Geographical Sciences) explained: ‘With the same climate models used to study future climate change, we studied how a doubling of carbon dioxide concentrations would affect rainfall patterns on a world with Eocene geography. This increased the overall global precipitation – warmer air holds more water.  But it also changed the pattern and frequency of extreme events.  The tropics became wetter and the incidence of extreme events increased, by as much as 70% in some tropical regions. In other places, total annual precipitation and the number of extreme events became decoupled; in other words, those areas became drier, with less frequent but more extreme events.  All of this illustrates the complexity of how global warming will affect our local, regional and global rainfall patterns.’

Co-author Professor Rich Pancost (School of Earth Sciences), explained how these findings agree with a range of geological and chemical features of the Palaeocene-Eocene global warming: ‘This warming event is associated with major changes in how soil and sediment were eroded and moved around the landscape.  In many places, river systems that had been transporting silt or sand became associated with fist-sized rocks or even boulders; and more sediment was transported to and buried in coastal margins. In some locations, the rate of sediment accumulation increased by a factor of ten. But at the same time, there is also evidence that these systems became more arid.  Our climate simulations reconcile this; many locations do experience an increase in aridity but also more intense rainfall events.  Those events were likely responsible for increased energy in these systems, moving around more material and larger objects. Ultimately it flushed more sediment to the ocean, causing eutrophication, blooms of algae and in some cases hypoxia.’ [Analogous but less severe than Oceanic Anoxic Events.]

Photo of the Claret Conglomerate by Rob Duller, University of Liverpool.  I wrote about this here: “In central Spain, outcropping on dusty hillsides overlooking apparently endless miles of gnarled olive trees, is the Esplugafreda Formation. The Formation consists of hundreds of metres of rusty-coloured palaeosols and the remains of ancient channels, part of a more-than-55-million-year-old braided river system. What is particularly striking about these rocks is that atop them sits the Claret Conglomerate, a unit not of silt, sand and ancient soil, but of pebbles, fist-sized stones and even boulders. These stones are part of the same river system but were deposited under conditions with far more energy: the Conglomerate represents a relatively transient moment in Earth history of remarkably intense rainfall events. And these events were probably caused by ancient global warming.”

Co-author Professor Dan Lunt (School of Geographical Sciences) elaborated on this: ‘There are many similar events in Earth history, where warming appears to have been associated with changes in rainfall and sedimentary systems.  Although we have not investigated them here, it is very likely that our results are translatable – because the physics that underpins them remains the same.  Thus, the collective body of research confirms that global warming in the past and the future will be associated with more ‘flashy’ rainfall, with implications for flooding and water management.’

Professor Pancost elaborated: ‘Past climate has lessons for our future.  Not only do the models show evidence for more intense rainfall events – with all of the associated implications – but they are consistent with all of our other data. In fact, they explain inconsistencies in our other data and confirm some long-established hypotheses. In doing so, they foreshadow our potential future with complex and dramatic changes in rainfall, more flooding and more soil erosion.’

Response of the hydrological cycle to doubling of carbon dioxide concentrations:

Fig. 2

From the paper: Figure a shows the expected impact of a doubling of CO2 on global precipitation patterns – dry areas get drier and wet areas get wetter. However, (b) shows that the number of actual precipitation events decreases almost everywhere.  Both (c) and (d) show different mathematical expressions of ‘extreme’ events, and both show that nearly global increase in the number of extreme events.

The article is: Carmichael, M., Pancost, R.D. and Lunt, D.J. (2018) Changes in the occurrence of extreme precipitation events at the Paleocene-Eocene thermal maximum.  Earth and Planetary Science Letters 501, 24-36.

It is available here: