carbon dioxide – Cabot Institute for the Environment blog

Are you a journalist looking for climate experts for COP28? We’ve got you covered

Posted on October 30, 2023November 28, 2023 by amanda.woodman-hardy

We’ve got lots of media trained climate change experts. If you need an expert for an interview, here is a list of our experts you can approach. All media enquiries should be made via Victoria Tagg, our dedicated Media and PR Manager at the University of Bristol.

Email victoria.tagg@bristol.ac.uk or call +44 (0)117 428 2489.

Climate change / climate emergency / climate science / climate-induced disasters

Dr Eunice Lo – expert in changes in extreme weather events such as heatwaves and cold spells, and how these changes translate to negative health outcomes including illnesses and deaths. Follow on Twitter/X @EuniceLoClimate.

Professor Daniela Schmidt – expert in the causes and effects of climate change on marine systems. Dani is also a Lead Author on the IPCC reports.

Dr Katerina Michalides – expert in drylands, drought and desertification and helping East African rural communities to adapt to droughts and future climate change. Follow on Twitter/X @_kmichaelides.

Professor Dann Mitchell – expert in how climate change alters the atmospheric circulation, extreme events, and impacts on human health. Dann is also a Met Office Chair. Follow on Twitter/X @ClimateDann.

Professor Dan Lunt – expert on past climate change, with a focus on understanding how and why climate has changed in the past and what we can learn about the future from the past. Dan is also a Lead Author on IPCC AR6. Follow on Twitter/X @ClimateSamwell.

Professor Jonathan Bamber – expert on the impact of melting land ice on sea level rise (SLR) and the response of the ocean to changes in freshwater forcing. Follow on Twitter/X @jlbamber

Professor Paul Bates CBE – expert in the science of flooding, risk and reducing threats to life and economic losses worldwide. Follow on Twitter/X @paul_d_bates

Dr Matt Palmer – expert in sea level and ocean heat content at the Met Office Hadley Centre and University of Bristol. Follow on Twitter/X @mpclimate.

Professor Guy Howard – expertise in building resilience and supporting adaptation in water systems, sanitation, health care facilities, and housing. Expert in wider infrastructure resilience assessment.

Net Zero / Energy / Renewables

Dr Caitlin Robinson – expert on energy poverty and energy justice and also in mapping ambient vulnerabilities in UK cities. Caitlin will be virtually attending COP28. Follow on Twitter/X @CaitHRobin.

Professor Philip Taylor – Expert in net zero, energy systems, energy storage, utilities, electric power distribution. Also Pro-Vice Chancellor at the University of Bristol. Follow on Twitter/X @rolyatlihp.

Dr Colin Nolden – expert in sustainable energy policy, regulation and business models and interactions with secondary markets such as carbon markets and other sectors such as mobility. Colin will be in attendance in the Blue Zone at COP28 during week 2.

Professor Charl Faul – expert in novel functional materials for sustainable energy applications e.g. in CO2 capture and conversion and energy storage devices. Follow on Twitter/X @Charl_FJ_Faul.

Climate finance / Loss and damage

Dr Rachel James – Expert in climate finance, damage, loss and decision making. Also has expertise in African climate systems and contemporary and future climate change. Follow on Twitter/X @_RachelJames.

Dr Katharina Richter – expert in decolonial environmental politics and equitable development in times of climate crises. Also an expert on degrowth and Buen Vivir, two alternatives to growth-based development from the Global North and South. Katarina will be virtually attending COP28. @DrKatRichter.

Climate justice

Dr Alix Dietzel – climate justice and climate policy expert. Focusing on the global and local scale and interested in how just the response to climate change is and how we can ensure a just transition. Alix will be in attendance in the Blue Zone at COP28 during week 1. Follow on Twitter/X @alixdietzel.

Dr Ed Atkins – expert on environmental and energy policy, politics and governance and how they must be equitable and inclusive. Also interested in local politics of climate change policies and energy generation and consumption. Follow on Twitter/X @edatkins_.

Dr Karen Tucker – expert on colonial politics of knowledge that shape encounters with indigenous knowledges, bodies and natures, and the decolonial practices that can reveal and remake them. Karen will be in attending the Blue Zone of COP28 in week 2.

Climate change and health

Dr Dan O’Hare – expert in climate anxiety and educational psychologist. Follow on Twitter/X @edpsydan.

Professor Guy Howard – expert in influence of climate change on infectious water-related disease, including waterborne disease and vector-borne disease.

Professor Rachael Gooberman-Hill – expert in health research, including long-term health conditions and design of ways to support and improve health. @EBIBristol (this account is only monitored in office hours).

Youth, children, education and skills

Dr Dan O’Hare – expert in climate anxiety in children and educational psychologist. Follow on Twitter/X @edpsydan.

Dr Camilla Morelli – expert in how children and young people imagine the future, asking what are the key challenges they face towards the adulthoods they desire and implementing impact strategies to make these desires attainable. Follow on Twitter/X @DrCamiMorelli.

Dr Helen Thomas-Hughes – expert in engaging, empowering, and inspiring diverse student bodies as collaborative environmental change makers. Also Lead of the Cabot Institute’s MScR in Global Environmental Challenges. Follow on Twitter/X @Researchhelen.

Professor Daniela Schmidt – expert in the causes and effects of climate change on marine systems. Dani is also a Lead Author on the IPCC reports. Also part of the Waves of Change project with Dr Camilla Morelli, looking at the intersection of social, economic and climatic impacts on young people’s lives and futures around the world.

Climate activism / Extinction Rebellion

Dr Oscar Berglund – expert on climate change activism and particularly Extinction Rebellion (XR) and the use of civil disobedience. Follow on Twitter @berglund_oscar.

Land / Nature / Food

Dr Jo House – expert on land and climate interactions, including emissions of carbon dioxide from land use change (e.g. deforestation), climate mitigation potential from the land (e.g. afforestation, bioenergy), and implications of science for policy. Previously Government Office for Science’s Head of Climate Advice. Follow on Twitter @Drjohouse.

Professor Steve Simpson – expert marine biology and fish ecology, with particular interests in the behaviour of coral reef fishes, bioacoustics, effects of climate change on marine ecosystems, conservation and management. Follow on Twitter/X @DrSteveSimpson.

Dr Taro Takahashi – expert on farming, livestock production systems as well as programme evaluation and general equilibrium modelling of pasture and livestock-based economies.

Dr Maria Paula Escobar-Tello – expert on tensions and intersections between livestock farming and the environment.

Air pollution / Greenhouse gases

Dr Aoife Grant – expert in greenhouse gases and methane. Set up a monitoring station at Glasgow for COP26 to record emissions.

Professor Matt Rigby – expert on sources and sinks of greenhouse gases and ozone depleting substances. Follow on Twitter @TheOtherMRigby.

Professor Guy Howard – expert in contribution of waste and wastewater systems to methane emissions in low- and middle-income countries

Plastic and the environment

Dr Charlotte Lloyd – expert on the fate of chemicals in the terrestrial environment, including plastics, bioplastics and agricultural wastes. Follow on Twitter @DrCharlLloyd.

Cabot Institute for the Environment at COP28

We will have three media trained academics in attendance at the Blue Zone at COP28. These are: Dr Alix Dietzel (week 1), Dr Colin Nolden (week 2) and Dr Karen Tucker (week 2). We will also have two academics attending virtually: Dr Caitlin Robinson and Dr Katharina Richter.

Read more about COP on our website at https://bristol.ac.uk/cabot/what-we-do/projects/cop/
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This blog was written by Amanda Woodman-Hardy, Communications and Engagement Officer at the Cabot Institute for the Environment. Follow on Twitter @Enviro_Mand and @cabotinstitute.

Watch our Cabot Conversations – 10 conversations between 2 experts on a climate change issue, all whilst an artist listens in the background and interprets the conversation into a beautiful piece of art in real time. Find out more at bristol.ac.uk/cabot/conversations.

Limiting global warming to 2℃ is not enough – why the world must keep temperature rise below 1℃

Posted on June 29, 2023 by amanda.woodman-hardy

Warming of more than 1℃ risks unsafe and harmful outcomes for humanity.
Ink Drop/Shutterstock

The Paris Climate agreement represented a historic step towards a safer future for humanity on Earth when it was adopted in 2015. The agreement strove to keep global heating below 2℃ above pre-industrial levels with the aim of limiting the increase to 1.5℃ if possible. It was signed by 196 parties around the world, representing the overwhelming majority of humanity.

But in the intervening eight years, the Arctic region has experienced record-breaking temperatures, heatwaves have gripped many parts of Asia and Australia has faced unprecedented floods and wildfires. These events remind us of the dangers associated with climate breakdown. Our newly published research argues instead that humanity is only safe at 1℃ of global warming or below.

While one extreme event cannot be solely attributed to global heating, scientific studies have shown that such events are much more likely in a warmer world. Since the Paris agreement, our understanding of the impacts of global heating have also improved.

A fishing boat surrounded by icebergs that have come off a glacier. — Fishing boat dwarfed by icebergs that came off Greenland’s largest glacier, Jakobshavn Isbrae.
Jonathan Bamber, Author provided

Rising sea levels are an inevitable consequence of global warming. This is due to the combination of increased land ice melting and warmer oceans, which cause the volume of ocean water to increase. Recent research shows that in order to eliminate the human-induced component of sea-level rise, we need to return to temperatures last seen in the pre-industrial era (usually taken to be around 1850).

Perhaps more worrying are tipping points in the climate system that are effectively irreversible on human timescales if passed. Two of these tipping points relate to the melting of the Greenland and West Antarctic ice sheets. Together, these sheets contain enough ice to raise the global sea level by more than ten metres.

The temperature threshold for these ice sheets is uncertain, but we know that it lies close to 1.5℃ of global heating above pre-industrial era levels. There’s even evidence that suggests the threshold may already have been passed in one part of west Antarctica.

Critical boundaries

A temperature change of 1.5℃ might sound quite small. But it’s worth noting that the rise of modern civilisation and the agricultural revolution some 12,000 years ago took place during a period of exceptionally stable temperatures.

Our food production, global infrastructure and ecosystem services (the goods and services provided by ecosystems to humans) are all intimately tied to that stable climate. For example, historical evidence shows that a period called the little ice age (1400-1850), when glaciers grew extensively in the northern hemisphere and frost fairs were held annually on the River Thames, was caused by a much smaller temperature change of only about 0.3℃.

A sign marking the retreat of a glacier since 1908. — Jasper National Park, Canada. Glaciers used to grow extensively in the Northern Hemisphere.
Matty Symons/Shutterstock

A recent review of the current research in this area introduces a concept called “Earth system boundaries”, which defines various thresholds beyond which life on our planet would suffer substantial harm. To avoid passing multiple critical boundaries, the authors stress the need to limit temperature rise to 1℃ or less.

In our new research, we also argue that warming of more than 1℃ risks unsafe and harmful outcomes. This potentially includes sea level rise of multiple metres, more intense hurricanes and more frequent weather extremes.

More affordable renewable energy

Although we are already at 1.2℃ above pre-industrial temperatures, reducing global temperatures is not an impossible task. Our research presents a roadmap based on current technologies that can help us work towards achieving the 1℃ warming goal. We do not need to pull a technological “rabbit out of the hat”, but instead we need to invest and implement existing approaches, such as renewable energy, at scale.

Renewable energy sources have become increasingly affordable over time. Between 2010 and 2021, the cost of producing electricity from solar energy reduced by 88%, while wind power saw a reduction of 67% over the same period. The cost of power storage in batteries (for when the availability of wind and sunlight is low) has also decreased, by 70% between 2014 and 2020.

An aerial photograph of a photovoltaic power plant on a lush hillside. — A photovoltaic power plant in Yunnan, China.
Captain Wang/Shutterstock

The cost disparity between renewable energy and alternative sources like nuclear and fossil fuels is now huge – there is a three to four-fold difference.

In addition to being affordable, renewable energy sources are abundantly available and could swiftly meet society’s energy demands. Massive capacity expansions are also currently underway across the globe, which will only further bolster the renewable energy sector. Global solar energy manufacturing capacity, for example, is expected to double in 2023 and 2024.

Removing carbon dioxide from the atmosphere

Low-cost renewable energy will enable our energy systems to transition away from fossil fuels. But it also provides the means of directly removing CO₂ from the atmosphere at a large scale.

CO₂ removal is crucial for keeping warming to 1℃ or less, even though it requires a significant amount of energy. According to research, achieving a safe climate would require dedicating between 5% and 10% of total power generation demand to effective CO₂ removal. This represents a realistic and attainable policy option.

Various measures are used to remove CO₂ from the atmosphere. These include nature-based solutions like reforestation, as well as direct air carbon capture and storage. Trees absorb CO₂ from the atmosphere through photosynthesis and then lock it up for centuries.

A group of people planting a mangrove forest next to the sea. — A mangrove forest being planted in Klong Khone Samut Songkhram Province, Thailand.
vinai chunkhajorn/Shutterstock

Direct air capture technology was originally developed in the 1960s for air purification on submarines and spacecrafts. But it has since been further adapted for use on land. When combined with underground storage methods, such as the process of converting CO₂ into stone, this technology provides a safe and permanent method of removing CO₂ from the atmosphere.

Our paper demonstrates that the tools and technology exist to achieve a safer, healthier and more prosperous future – and that it’s economically viable to do so. What appears to be lacking is the societal will and, as a consequence, the political conviction and commitment to achieve it.

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This blog is written Cabot Institute for the Environment member Jonathan Bamber, Professor of Glaciology and Earth Observation, University of Bristol and Christian Breyer, Professor of Solar Economy, Lappeenranta University of Technology. This article is republished from The Conversation under a Creative Commons license. Read the original article.

Countries may be under-reporting their greenhouse gas emissions – that’s why accurate monitoring is crucial

Posted on November 16, 2021April 16, 2023 by janet.crompton

Pledges to cut greenhouse gas emissions are very welcome – but accurate monitoring across the globe is crucial if we are to meet targets and combat the devastating consequences of global warming.

During COP26 in Glasgow, many countries have set out their targets to reach net-zero by the middle of this century.

But a serious note of caution was raised in a report in the Washington Post. It revealed that many countries may be under-reporting their emissions, with a gap between actual emissions into the atmosphere and what is being reported to the UN.

This is clearly a problem: if we are uncertain about what we are emitting now, we will not know for certain that we have achieved our emission reduction targets in the future.

Quantifying emissions

Currently, countries must follow international guidelines when it comes to reporting emissions. These reports are based on “bottom-up” methods, in which national emissions are tallied up by combining measures of socioeconomic activity with estimates on the intensity of emissions involved in those activities. For example, if you know how many cows you have in your country and how much methane a typical cow produces, you can estimate the total methane emitted from all the cows.

There are internationally agreed guidelines that specify how this kind of accountancy should be done, and there is a system of cross-checking to ensure that the process is being followed appropriately.

But, according to the Washington Post article, there appear to be some unexpected differences in emissions being reported between similar countries.

The reporting expectations between countries are also considerably different. Developed countries must report detailed, comprehensive reports each year. But, acknowledging the administrative burden of this process, developing countries can currently report much more infrequently.

Plus, there are some noteable gaps in terms of what needs to be reported. For example, the potent greenhouse gases that were responsible for the depletion of the stratospheric ozone layer – such as chlorofluorocarbons (CFCs) – are not included.

A ‘top-down’ view from the atmosphere

To address these issues, scientists have been developing increasingly sophisticated techniques that use atmospheric greenhouse gas observations to keep track of emissions. This “top-down” view measures what is in the atmosphere, and then uses computer models to work backwards to figure out what must have been emitted upwind of the measurements.

To demonstrate the technique, an international team of scientists converged on Glasgow, to observe how carbon dioxide and methane has changed during the COP26 conference.

While this approach cannot provide the level of detail on emission sectors (such as cows, leaks from pipes, fossil fuels or cars) that the “bottom–up” methods attempt, scientists have demonstrated that it can show whether the overall inventory for a particular gas is accurate or not.

The UK was the first country, now one of three along with Switzerland and Australia, to routinely publish top-down emission estimates in its annual National Inventory Report to the United Nations.

A network of five measurement sites around the UK and Ireland continuously monitors the levels of all the main greenhouse gases in the air using tall towers in rural regions.

Emissions are estimated from the measurements using computer models developed by the Met Office. And the results of this work have been extremely enlightening.

In a recent study, we showed that the reported downward trend in the UK’s methane emissions over the last decade is mirrored in the atmospheric data. But a large reported drop before 2010 is not, suggesting the methane emissions were over-estimated earlier in the record.

In another, we found that the UK had been over-estimating emissions of a potent greenhouse gas used in car air conditioners for many years. These studies are discussed with the UK inventory team and used to improve future inventories.

While there is currently no requirement for countries to use top-down methods as part of their reporting, the most recent guidelines and a new World Meteorological Organisation initiative advocate their use as best practice.

If we are to move from only three countries evaluating their emissions in this way, to a global system, there are a number of challenges that we would need to overcome.

Satellites may provide part of the solution. For carbon dioxide and methane, the two most important greenhouse gases, observations from space have been available for more than a decade. The technology has improved dramatically in this time, to the extent that imaging of some individual methane plumes is now possible from orbit.

In 2018, India, which does not have a national monitoring network, used these techniques to include a snapshot of its methane emissions in its report to the UN.

But satellites are unlikely to provide enough information alone.

To move towards a global emissions monitoring system, space-based and surface-based measurements will be required together. The cost to establish ground-based systems such as the UK’s will be somewhere between one million and tens of millions of dollars per country per year.

But that level of funding seems achievable when we consider that billions have been pledged for climate protection initiatives. So, if the outcome is more accurate emissions reporting, and a better understanding of how well we are meeting our emissions targets, such expenditure seems like excellent value for money.

It will be up to the UN and global leaders to ensure that the international systems of measurement and top-down emissions evaluation can be scaled-up to meet the demands of a monitoring system that is fit for purpose. Without robust emissions data from multiple sources, the accuracy of future claims of emission reductions may be called into question.

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This blog is written by Cabot Institute for the Environment member Professor Matt Rigby, Reader in Atmospheric Chemistry, University of Bristol

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Back to the Future ‘Hothouse’

Posted on August 16, 2018April 4, 2023 by janet.crompton

Our current global warming target and the trajectory it places us on, towards a future ‘Hothouse Earth’, has been the subject of much recent discussion, stimulated by a paper by Will Steffen and colleagues. In many respects, the key contribution of this paper and similar work is to extend the temporal framing of our climate discussions, beyond 2100 for several centuries or more. Analogously, it is useful to extend our perspective backwards to similar time periods, to reflect on the last time Earth experienced such a Hothouse state and what it means.

The Steffen et al paper allows for a variety of framings, all related to the range of natural physical, biological and chemical feedbacks that will amplify or mitigate the human intervention in climate. [Note: the authors frame their paper around the concept of a limited number of steady state scenarios/temperatures for the Earth. They then argue that aiming for 2C, potentially an unstable state, could trigger feedbacks tipping the world towards the 4C warmer Hothouse. I find that to be somewhat simplistic given the diversity of climate states that have existed, if even transiently, over the past 15 million years, but that is a discussion for another day.] From my perspective, the most useful framing – and one that remains true to the spirit of the paper is this: We have set a global warming limit of 2C by 2100, with an associated carbon budget. What feedback processes will that carbon budget and warming actually unleash over the coming century, how much additional warming will they add, and when?

That is a challenging set of questions that comes with a host of caveats, most related to the profound uncertainty in the interlinked biogeochemical processes that underpin climate feedbacks. For example, as global warming thaws the permafrost, will it release methane (with a high global warming potential than carbon dioxide)? Will the thawed organic matter oxidise to carbon dioxide or will it be washed and buried in the ocean? And will the increased growth of plants under warmer conditions lead instead to the sequestration of carbon dioxide? The authors refer to previous studies that suggest a permafrost feedback yielding an additional 0.1C warming by the end of the century; but there is great uncertainty in both the magnitude of that impact and its timing.

And timing is the great question at the heart of this perspective piece. I welcome it, because too often our perspective is fixed on the arbitrary date of 2100, knowing full well that the Earth will continue to warm and ice continue to melt long after that date. In this sense, Steffen et al is not a contradiction to what has been reported from the IPCC but an expansion on it.

Classically, we discuss these issues in terms of fast and slow feedbacks, but in fact there is a continuum between near instantaneous feedbacks and those that act over hundreds, thousands or even millions of years. A warmer atmosphere will almost immediately hold more water vapour, providing a rapid positive feedback on warming – and one that is included in all of those IPCC projections. More slowly, soil carbon, including permafrost, will begin to oxidise, with microbial activity stimulated and accelerated under warmer conditions – a feedback that is only just now being included in Earth system models. And longer term, all manner of processes will come into play – and eventually, they will include the negative feedbacks that have helped regulate Earth’s climate for the past 4 billion years.

There is enough uncertainty in these processes to express caution in some of the press’s more exuberant reporting of this topic. But lessons from the past certainly underscore the concerns articulated by Steffen et al. We think that the last time Earth had 410 ppm CO2, a level similar to what you are breathing right now, was the Pliocene about 3 million years ago. This was a world that was 1 to 2C warmer than today (i.e. 2 to 3C warmer than the pre-industrial Earth) and with sea levels about 10 m higher. This suggests that we are already locked into a world that far exceeds the ambitions and targets of the Paris Agreement. This is not certain as we live on a different planet and one where the great ice sheets of Greenland and Antarctica might not only be victims of climate change but climate stabilisers through ice-sheet hysteresis. And even if a Pliocene future is fixed, it might take centuries for that warming and sea level change to be realised.

But that analogue does suggest caution, as advocated by the Hothouse Earth authors.

It also prompts us to ask what the Earth was like the last time its atmosphere held about 500 ppm CO2, similar to the level needed to achieve the Paris Agreement to limit end-of-century warming below 2C. A useful analogue for those greenhouse gas levels is the Middle Miocene Climate Optimum, which occurred from 17 to 14.7 million years ago.

Figure showing changes in ocean temperature (based on oxygen isotopic compositions of benthic foraminifera) and pCO2 over the past 60 million years (from Palaeo-CO2). Solid symbols are from the d11B isotope proxy and muted symbols are from the alkenone-based algal carbon isotope fractional proxy. Note the spike in pCO2 associated with the MMCO at about 15 million years ago.

As one would expect for a world with markedly higher carbon dioxide levels, the Miocene was hotter than the climate of today. And consistent with many of Steffen et al.’s arguments, it was about 4C hotter rather than a mere 2C, likely due to the range of carbon cycle and ice-albedo feedbacks they describe. But such warmth was not uniform – globally warmer temperatures of 4C manifest as far hotter temperatures in some parts of the world and only slightly warmer temperatures elsewhere. Pollen and microbial molecular fossils from the North Sea, for example, indicate that Northern Europe experienced sub-tropical climates.

But what were the impacts of this warmth? What is a 4C warmer world like? To understand that, we also need to understand the other ways in which the Miocene world differed from ours, not just due to carbon dioxide concentrations but also the ongoing movement of the continents and the continuing evolution of life. In both respects, the Miocene was broadly similar to today. The continents were in similar positions, and the geography of the Miocene is one we would recognise. But there were subtle differences, including the ongoing uplift of the Himalayas and the yet-to-be-closed gateway between North and South America, and these subtle differences could have had major impacts on Asian climate and the North Atlantic circulation, respectively.

Similarly, the major animal groups had evolved by this point, and mammals had firmly established their dominance in a world separated by 50 million years from the dinosaurs. Remnant groups from earlier times (hell pigs!) still terrorised the landscape, but many of the groups were the same or closely related to those we would recognise today. And although hominins would not appear until the end of the Miocene, the apes had become well established, represented by as many as a 100 species. In the oceans, the differences were perhaps more apparent, the seas thriving with the greatest diversity of cetaceans in the history of our planet and associated with them the gigantic macro-predators such as Charcharadon megalodon (The MegTM).

Smithsonian mural showing Miocene Fauna and landscape.

But it is the plants that exhibit the most pronounced differences between modern and Miocene life. Grasses had only recent proliferated across the planet at the time of the MMCO, and the C4 plants had yet to expand to their current dominance. And in this regard, the long-term evolution of Earth’s climate likely played a crucial role. There are about 8100 species of C4 plants (although this comprises only 3% of the plant species known to us) and most of these are grasses with other notable species being maize and sugar cane. They are distinguished from the dominant C3 plants, which comprise almost all other species, by virtue of their carbon dioxide assimilation biochemistry (the Hatch-Slack mechanism) and their leaf cellular physiology (the Kranz leaf anatomy). It is a collective package that is exceptionally well adapted to low carbon dioxide conditions, and their global expansion about 7 million years ago was almost certainly related to the long-term decline in carbon dioxide from the high levels of the Middle Miocene. Although C4 plants only represent a small proportion of modern plant species, the Miocene world, bereft of them, would have looked far different than today – lacking nearly half of our modern grass species and by extension clear analogues to the vast African savannahs.

Aside from these, the most profound differences between the Miocene world and that of today would have been the direct impacts of higher global temperatures. There is strong evidence that the Greenland ice sheet was far reduced in size compared to that of today, and its extent and even whether or not it was a persistent ice sheet or an ephemeral one remains the subject of debate. Similarly, West Antarctica was likely devoid of permanent ice, and the East Antarctic Ice Sheet was probably smaller – perhaps far smaller – than it is today. And collectively, these smaller ice sheets were associated with a sea level that was about 40 m higher than that of today.

The hot Miocene world would have been different in other ways, including the hydrological cycle. Although less studied than for other ancient intervals, it is almost certain that elevated warmth – and markedly smaller equator-to-pole temperature differences – would have impacted the global distribution of water. More water was evidently exported to the high latitudes, resulting in a warmer and vegetated Antarctica where the ice had retreated. It was also likely associated with far more extreme rainfall events, with the hot air able to hold greater quantities of water. More work is needed, but it is tempting to imagine the impact of these hot temperatures and extreme rainfall events. They would have eroded the soil and flushed nutrients to the sea, perhaps bringing about the spread of anoxic dead zones, similar to the Oceanic Anoxic Events of the Mesozoic or the dead zones of modern oceans caused by agricultural run-off. Indeed, the Miocene is characterised by the deposition of some very organic-rich rocks, including the North Pacific Monterey Formation, speaking to the occurrence of reduced oxygen levels in parts of these ancient oceans.

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It is unclear if our ambitions to limit global warming to 2C by the end of this century really have put us on a trajectory for 4C. It is unclear if we are destined to return to the Miocene.

But if so, the Miocene world is one both similar to but markedly distinct from our own – a world of hotter temperatures, extremes of climate, fewer grasslands, Antarctic vegetation, Arctic forests and far higher sea levels. Crucially, it is not the world for which our current society, its roads, cities, power plants, dams, borders, farmlands and treaties, has been designed.

Moreover, the MMCO Earth is a world that slowly evolved from an even warmer one over millions of years*; and that then evolved over further millions of years to the one in which we now inhabit. It is not a world that formed in a hundred or even a thousand years. And that leaves us three final lessons from the past. First, we do not know how the life of this planet, from coral reefs to the great savannahs, will respond to such geologically rapid change. Second, we do not know how we will respond to such rapid change; if we must adapt, we must learn how to do so creatively, flexibly and equitably. And third, it is probably not too late to prevent such a future from materialising, but even if it is, we still must act to slow down that rate of change to which we must adapt.

And we still must act to ensure that our future world is only 4C hotter and analogous to the Miocene; if we fail to act, the world will be even hotter, and we will have to extend our geological search 10s of millions of years further into the past, back to the Eocene, to find an even hotter and extreme analogue for our future Hothouse World.

*The final jump into the MMCO appears to have been somewhat more sudden, but still spanned around two-hundred thousand years. A fast event geologically but not on the timescales of human history.

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This blog is written by Cabot Institute member Professor Rich Pancost, Head of Earth Sciences at the University of Bristol. This blog has been reposted with kind permission from Rich’s original blog.

Rich Pancost

A response to Trump’s withdrawal from the Paris Agreement

Posted on June 5, 2017April 6, 2023 by janet.crompton

The decision by President Trump to withdraw from the Paris Agreement on Climate Change puts the United States at odds with both science and global geopolitical norms. The fundamentals of climate change remain unambiguous: greenhouse gas concentrations are increasing, they are increasing because of human action, the increase will cause warming, and that warming creates risks of extreme weather, food crises and sea level rise. That does not mean that scientists can predict all of the consequences of global warming, much work needs to be done, but the risks are both profound and clear. Nor do we know what the best solutions will be – there is need for a robust debate about the nature, fairness and efficacy of different decarbonisation policies and technologies as well as the balance of responsibility; the Paris Agreement, despite its faults with respect to obligation and enforcement, allowed great flexibility in that regard, which is why nearly every nation on Earth is a signatory.

Moreover, although climate change affects us all, it will affect the poorest and most vulnerable the most. They, despite being least responsible, bear the greatest risks and the greatest burdens. For the President of the world’s second largest carbon polluter to blatantly disregard such evidence and injustice, to refuse to even acknowledge the consequences of its actions and to disengage with this relatively modest and non-binding agreement puts it odds with the norms of global partnership and human rights. This abrogation of responsibility is particularly profound because President Trump has also withdrawn the United States from the Green Climate Fund, which helps the poorest of the world adapt to the climate change that his actions make more likely.

And to what end? Other nations will now assume global leadership, politically, morally and technologically. It will likely cost American businesses money, hinder innovation in one of the world’s most dynamic sectors, and ultimately cost jobs. It will likely undermine the United States’ global stature and diplomatic reach. It is hard to imagine a decision so blatantly motivated by self-interest while being so profoundly self-harming.

The crucial question now is how we respond. China and the EU have stepped forward, increasing their voluntary commitments, repudiating President Trump’s decision and assuming the mantle of leadership. Nations around the world are following suit, as are cities and states across the United States. Businesses have re-stated their commitment to decarbonisation – ironically, the day before Trump’s decision, shareholders voted that Exxon develop plans compliant with the Paris Agreement’s targets. In the UK, in the midst of a general election, parties from across the political spectrum have responded to Trump’s decision with reactions ranging from disappointment to outrage. The UK has always provided leadership in this arena, recognising that climate change is a non-partisan issue, and it is one of the few nations with a cross party Climate Change Act. It is vital for both the planet and the UK that these initial comments are followed by bolder actions and stronger leadership.

Across the world and in the University of Bristol, we are frustrated with the symbolism of Trump’s actions, his speech’s misrepresentation of facts, and his decision’s potential to slow climate action. But we also recognise that these actions will not stop climate action. The responses of local, national and international leaders, in politics, community groups and businesses, across sectors and across society show that no person, regardless of his position or his nation, can stop the energy revolution. It is too deeply embedded in our politics, economy and ambitions, borne of out of multiple necessities.

Here, in the University of Bristol Cabot Institute, we remain committed to this challenge. Our University is committed to carbon neutrality, ethical and low-carbon procurement and divestment from fossil fuel-intensive businesses. We have foregrounded Sustainable Futures in our undergraduate teaching. And in our research, we are investigating improved energy efficiency in everything from computer software, to our homes and our cities. We are exploring how smart technology enables new forms of transport, community energy and individual action. We are converting nuclear waste into diamond batteries with 5000-year lifetimes, we are leading one of the projects under the Natural Environment Research Council’s Greenhouse Gas Reduction programme and we have just launched new initiatives in wind, tidal, solar and nuclear energy.

Our ambitions are at all scales, from the local to the global. We continue to work with our Green Capital partners, with a focus on building an informed, diverse, inclusive and powerful movement to become a more sustainable city and region, exemplified by the Green and Black Ambassadors Initiative. Globally, our projects have been exploring the impact of conflict, climate change and geological hazards on development and the environment; the potential for micro-grids to deliver electricity to isolated communities; new forms of parasite resistance for subsistence farmers; and how geothermal energy can be harnessed in Ethiopia.

This commitment to sustainability builds on five decades of research on our environmental challenges and how to manage them. The Atmospheric Chemistry Research Group makes among the world’s most accurate measurements of atmospheric concentrations of greenhouse gases, and they have shown how rapidly these compounds are accumulating. They are committed to refining those measurements and the modelling methods that allow us to understand why global emissions change. The Bristol Initiative for the Dynamic Global Environment reconstructs past climates and uses those insights to better understand our future; recent projects are building global collaborations to explore the controls on Earth’s temperature and monsoons. Our glaciologists study sea level rise; our hydrologists study floods and drought; our social scientists study the injustice of climate change and its impact on migration and conflict; and our vets and life scientists are exploring how to improve animal welfare and crop yields on a climate disrupted planet.

Our commitment includes appointing the best and the brightest at understanding these challenges, including Dr Dann Mitchell who joined the University in November. As co-ordinator of the largest dedicated project in the world on the climate impacts of the Paris Agreement (www.happimip.org), he sums up the Cabot Institute’s collective commitment: “The news of Trump wanting to pull out is incredibly frustrating. Our results are already suggesting more extreme events, such as droughts and heat waves, and serious impacts on society, such as increased human and animal health issues, failures in global crop distributions and bleaching of our coral reefs. I am frustrated that Trump continues to ignore the scientific evidence that has been recognised by his global peers, but that will not dissuade us from doing all we can to understand climate risks… and prevent them.’

Article by Professor Rich Pancost
Director of the University of Bristol Cabot Institute
Professor of Biogeochemistry
Royal Society Wolfson Research Merit Scholar

Hydrogen and fuel cells: Innovative solutions for low carbon heat

Posted on March 10, 2016April 12, 2023 by janet.crompton

On 29 February 2016, I attended a meeting in Westminster that was jointly organised by the UK Hydrogen and Fuel Cell Association (UKFCA) and Carbon Connect with the aim of discussing current challenges in the decarbonisation of heat generation in the UK. The panel included David Joffe (Committee on Climate Change), Dr. Marcus Newborough (ITM Power), Ian Chisholm (Doosan Babcock), Klaus Ullrich (Fuel Cell Energy Solutions), Phil Caldwell (Ceres Power) and was chaired by Dr Alan Whitehead MP and Shadow Energy Minister. The attendees included a number of key players in the field of hydrogen production, fuel cell and renewable energy industries, as well as organisations such as the Department for Energy and Climate Change (DECC).

To set the scene, I would like to quote some facts and figures from the 2015 Carbon Connect report on the Future of Heat (part II).

The 2025 carbon reduction target is 404.4 MtCO2e (million metric tons of carbon dioxide equivalent), but the reduction levels as of 2014 have only been 288.9 MtCO2e. The current Government’s low carbon policy framework is woefully inadequate to bridge this gap.
The government introduced the Renewable Heat Incentive in 2011, with the ambition of increasing the contribution of renewable energy source to 12% of the heat demand by 2020. Some of the initiatives include biomass, “energy from waste” and geothermal. However, clear policies and financial incentives are nowhere to be seen.
What is the current situation of renewable heat and how good is the 12% target? The good news is that there is a slight increase in the renewable share from 2004. The really bad news is that the contribution as of 2013 is just 2.6%. The UK is further behind any other EU state with regards to its renewable heat target. Sweden has a whopping 67.2% contribution and Finland 50.9%.

Towards a decarbonised energy sector, two important networks should be considered, electrical and gas. Electrification of heat is very well suited for low carbon heat generation, however, the electricity demands at peak time could be extremely costly. The UK’s gas network is a major infrastructure which is vital for providing gas during peak heat demand. However, it needs to be re-purposed in order to carry low carbon gas such as bio-methane, hydrogen or synthetic natural gas.

It was clear from the debate that hydrogen can play an important role in decreasing carbon emissions even within the current gas network. The introduction of up to 10% of hydrogen into gas feed can still be compatible with current gas networks and modern appliances, while generating a significant carbon emission reduction. However, where is the hydrogen coming from? For heat production at the national scale, steam reforming is the only player. However, with the government pulling away from carbon capture and storage (CCS), this option cannot provide a significant reduction in carbon emissions. Capital costs associated with electrolysers would not be able to deliver the amount of hydrogen required at peak demands. The frustration in this community with regards to the future of CCS was palpable during the networking session.

We need hydrogen, generated from renewable energy sources… but the question is how?

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This blog is written by Cabot Institute member David J. Fermin, Professor of Electrochemistry in the University of Bristol’s School of Chemistry. His research group are currently looking at the direct conversion of solar energy to chemical fuels, in particular hydrogen; the conversion of CO2 to fuels; and electrocatalysts for energy vectors (e.g. what you put in fuel cells and electrolysers).

David Fermin

David will be giving a free talk on the challenges of solar energy conversion and storage on Tuesday 12 April 2016 at 6.15 pm at the University of Bristol. To find out more and to book your ticket, visit the University of Bristol’s Public and Ceremonial Events web page.

Thoughts on passing 400 ppm

Posted on November 12, 2015April 12, 2023 by janet.crompton

In the next few days, the Mauna Loa atmospheric CO2 record will pass 400 ppm. This isn’t the first time that’s happened – we first crossed the 400 ppm threshold in May 2013, but the annual, saw-tooth variation in levels as the Northern hemisphere boreal forest breathes in and out has dipped us below 400 a couple of times since. This crossing is likely to be special however, as it is probably going to be the last time anybody alive today will experience an atmosphere with LESS than 400 ppm CO2.

Human emissions have been pushing up atmospheric levels by about 2.2 ppm every year in recent years, so normally we would expect the annual monthly minimum to increase to beyond 400 ppm from this year’s September minimum of 397.1 ppm, however we are in the midst of one of the largest El Nino years for over a decade, and the drought in the tropics during El Nino years slow the growth of trees relative to normal years, and increases fires. Previous strong El Nino years (like 1997) have helped to push the annual CO2 increase to a massive 3.7 ppm, and this year’s strong El Nino, coupled with increased forest burning in Indonesia, along with fossil fuel burning, have led Ralph Keeling to predict the annual rise could be as much as 4.4 ppm this year.

So why does it matter? 400 is in truth a fairly arbitrary value to get excited about, a neat quirk of our counting system and no more important as a value to the atmosphere than your car odometer ticking from 99,999 to 100,000. It doesn’t mean the car is going to collapse, but it certainly catches your attention. It’s the same with the atmosphere – it gives us pause to consider what we’ve done, and what it might mean for the climate system. For me, the most outrageous thing is that we, an insignificant population of carbon based life forms, have managed to alter the chemical composition of the atmosphere! And not just by a little – by a lot! And let’s not forget that the atmosphere is big – really big!

To me, as an Earth Scientist that leads me to think about when in Earth history the planet has experienced such high levels of CO2 before. Measuring atmospheric CO2 in the geological past is tricky – for the past ~800 thousand years we have a fantastic archive of trapped atmospheric gas bubbles in ice cores, and for the whole of that record CO2 never peaked above 300 ppm. Beyond the time for which we have the ice cores, we rely on geochemical proxies in marine and terrestrial sediments to estimate CO2 and that is the heart of my research. In a paper we published last year we showed that we have to go back to more than 2.3 Million years ago, to the very earliest Pleistocene and Pliocene to find atmospheric CO2 levels as high as we are about to permanently experience. What does that mean? Well the Pliocene was a similar world to today – the continents were in much the same place, the vegetation mix across this Earth was the same, except global temperatures were 2-3 degrees C higher than now, driven primarily by those high levels of CO2.

Another thing that strikes me today is how rapidly we’ve managed to change the atmosphere. In a little over 150 years since we started to burn fossil fuels with alacrity, we’ve gone from 280 ppm to 400 ppm. It’s hard to find geological records with the temporal precision to see changes that quick, but for sure we don’t know any time in Earth history when CO2 has changed so much, so quickly.

With COP21 in Paris just around the corner, perhaps saying goodbye to sub 400 ppm will focus minds to come up with a solution. I don’t know whether it will, or what a global solution would look like, but I hope beyond anything that we don’t do nothing.
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Cabot Institute member Dr Marcus Badger is a Research Associate in the Organic Geochemistry Group in the School of Chemistry. His research involves using biomolecules and climate models to better understand the Earth system.

Why forests are about more than just climate change

Posted on December 1, 2014April 14, 2023 by janet.crompton

It’s National Tree Week, and there is a plethora of talk about all the great things that trees do: encouraging biodiversity, providing a pleasant space for humans, and providing numerous ecosystem services. As well as this, there is some reference to how trees take in carbon dioxide, and the benefits of this for helping to prevent climate change. But what if trees didn’t help prevent climate change? What if actually, they increased climate change?

Afforestation (planting forests) is one of many suggestions as a way to deliberately change the earth’s climate to attempt to reverse the effects of climate change (known as ‘geoengineering’). Planting more trees seems like a an obvious, natural solution. Carbon offsetting, RED+ and lots of other schemes around the issue of climate change have been based on the preservation or increase of forests. But does it work?

We’ve known for some time that boreal forests contribute to climate change rather than help prevent it, because of changes in the surface reflectance (the albedo). But thus far, forests in other places have been thought to be beneficial, storing up carbon and not affecting the albedo so much.

But our recent study suggests that globally, preserving and expanding forests actually causes a net global warming. We used the Met Office’s latest climate model and did simulations of future climate change, with and without afforestion/forest preservation, and we found that though the deforestation has no discernable effect on the climate, the afforestation does.

Does this mean that we are advocating chopping down forests? No. As National Tree Week says, forests are about more than climate change. However much climate change is a key challenge for the future, we can’t forget that other things are important too. The climate effect of the forest preservation and expansion is small – only about 0.1 °C. How do you value that against the mass loss of biodiversity, irrelplaceable ecosystems and ecosystem services that would be lost?

Saving or planting forests is not a panacea for climate change, but neither is it the enemy. Conserving forest is worthwhile for lots of other reasons, but we shouldn’t kid ourselves that there won’t be difficult decisions to make about protecting the unique forest habitats, especially tropical forests like the Amazon, and preventing climate change.
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This blog was written by Cabot Institute member, T Davies-Barnard, University of Exeter.

The uncertain world

Posted on September 3, 2014April 14, 2023 by janet.crompton

J.G Ballard’s The Drowned World
taken from fantasticalandrewfox.com

Over the next 18 months, in collaboration with Bristol Green Capital 2015 artists, civic leaders and innovative thinkers, the Cabot Institute will be participating in a series of activities in which we examine how human actions are making our planet a much more uncertain place to live.

Fifty years ago, between 1962 and 1966, J. G. Ballard wrote a trio of seminal environmental disaster novels: The Drowned World, The Burning World and The Crystal World. These novels remain signposts to our future, the challenges we might face and the way people respond to rapid and unexpected change to their environment. In that spirit and coinciding with the Bristol Green Capital 2015, we introduce The Uncertain World, a world in which profound uncertainty becomes as much of a challenge to society as warming and rising sea levels.

For the past twenty years, the University of Bristol has been exploring how to better understand, mitigate and live with environmental uncertainty, with the Cabot Institute serving as the focus for that effort since its founding in 2010. Uncertainty is the oft-forgotten but arguably most challenging aspect of mankind’s centuries-long impact on the environment. We live our lives informed by the power of experience: our own as well as the collective experience of our families, communities and wider society. When my father started dairy farming he sought advice from my mother’s grandfather, our neighbours, and the grizzled veterans at the Middlefield auction house. Experience helps us make intelligent decisions, plan strategically and anticipate challenges.

Similarly, our weather projections, water management and hazard planning are also based on experience: tens to hundreds of years of observation inform our predictions of future floods, drought, hurricanes and heat waves. These records – this experience – can help us make sensible decisions about where to live, build and farm.

Now, however, we are changing our environment and our climate, such that the lessons of the past have less relevance to the planning of our future. In fact, many aspects of environmental change are unprecedented not only in human experience but in Earth history. As we change our climate, the great wealth of knowledge generated from human experience is losing capital every day.

The Uncertain World is not one of which we have no knowledge – we have high confidence that temperatures and sea level will rise, although there is uncertainty in the magnitude and speed of change. Nor should we view The Uncertain World with existential fear – we know that warm worlds have existed in the past. These were not inhospitable and most evidence from the past suggests that a climate ‘apocalypse’ resulting in an uninhabitable planet is unlikely.

Nonetheless, increasing uncertainty arising from human-induced changes to our global environment should cause deep concern. Crucial details of our climate remain difficult to predict, and it undermines our ability to plan for our future. We do not know whether many regions of the world will become wetter or dryer. This uncertainty propagates and multiplies through complex systems: how do we make sensible predictions of coastal flood risk when there is uncertainty in sea level rise estimates, rainfall patterns and the global warming that will impact both? We can make predictions even in such complex systems, but the predictions will inevitably come with a degree of uncertainty, a probabilistic prediction. How do we apply such predictions to decision making? Where can we build new homes, where do we build flood defences to protect existing ones, and where do we abandon land to the sea?

Perhaps most worrying, the consequences of these rapid changes on biological and chemical systems, and the people dependent upon them, are very poorly understood. For example, the synergistic impact of warmer temperatures, more acidic waters, and more silt-choked coastal waters on coral reefs and other marine ecosystems is very difficult to predict. This is particularly concerning given that more than 2.6 billion people depend on the oceans as their primary source of protein. Similarly, warming of Arctic permafrost could promote the growth of CO2-sequestering plants or the release of warming-accelerating methane – or both. Warm worlds with very high levels of carbon dioxide did exist in the past and these do provide some insight into the response of the Earth system, but we are accelerating into this new world at a rate that is unprecedented in Earth history, creating additional layers of uncertainty.

During late 2014 and 2015, the Cabot Institute will host a variety of events and collaborate with a variety of partners across Bristol and beyond to explore this Uncertain World and how we can live in it. How do we better explain uncertainty and what are the ‘logical’ decisions to make when faced with uncertainty? One of our first events will explore how uncertainty in climate change predictions should motivate us to action: the more uncertain our predictions the more we should employ mitigation rather than adaptation strategies. Future events will explore how past lessons from Earth history help us better understand potential future scenarios; how future scenario planning can inform the decisions we make today; and most importantly, how we build the necessary flexibility into social structures to thrive in this Uncertain World.

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

Prof Rich Pancost

Deep impact – the plastic on the seafloor; the carbon in the air

Posted on June 9, 2014April 14, 2023 by janet.crompton

We live in a geological age defined by human activity. We live during a time when the landscape of the earth has been transformed by men, its surface paved and cut, its vegetation manipulated, transported and ultimately replaced. A time when the chemical composition of the atmosphere, the rivers and the oceans has been changed – in some ways that are unique for the past million years and in other ways that are unprecedented in Earth history. In many ways, this time is defined not only by our impact on nature but by the redefinition of what it means to be human.

From a certain distance and perspective, the transformation of our planet can be considered beautiful. At night, the Earth viewed from space is a testament to the ubiquitous presence of the human species: cities across the planet glow with fierce intensity but so do villages in Africa and towns in the Midwest; the spotlights of Argentine fishing boats, drawing anchovies to the surface, illuminate the SW Atlantic Ocean; and the flames of flared gas from fracked oil fields cause otherwise vacant tracts of North Dakota to burn as bright as metropolises.

Environmental debates are a fascinating, sometimes frustrating collision of disparate ideas, derived from different experiences, ideologies and perspectives. And we learn even from those with whom we disagree. However, one perspective perpetually bemuses and perplexes me: the idea that it is impossible that man could so transform this vast planet. Of course, we can pollute an estuary, cause the Cuyahoga River to catch fire, turn Victorian London black or foul the air of our contemporary cities. We can turn the Great Plains into cornfields or into dust bowls, the rainforest into palm oil plantations, swamplands into cities and lowlands into nations. But these are local. Can we really be changing our oceans, our atmosphere, our Earth that much?

Such doubts underly the statements of, for example, UKIP Energy Spokesman Roger Helmer:

‘The theory of man-made climate change is unproven and implausible’.

It is a statement characterised by a breathless dismissal of scientific evidence but also an astonishingly naive view of man’s capacity to impact our planet.

There are places on Earth where the direct evidence of human intervention is small. There are places where the dominance of nature is vast and exhilarating and awe-inspiring. And across the planet, few places are entirely immune from reminders – whether they be earthquakes or volcanoes, tsunamis or hurricanes – that nature is vast and powerful.

But the Earth of the 21st century is a planet shaped by humans.

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A powerful example of humanity’s impact on our planet is our Plastic Ocean. We generate nearly 300 billion tons of plastic per year, much of it escaping recycling and much of that escaping the landfill and entering our oceans. One of the most striking manifestations of this is the vast trash vortex in the Northern Pacific Gyre. The size of the vortex depends on assumptions of concentration and is somewhat dependent on methodology, but estimates range from 700 thousand square kilometres to more than 15 million square kilometres. The latter estimate represents nearly 10% of the entire Pacific Ocean. Much of the plastic in the trash vortex – and throughout our oceans – occurs as fine particles invisible to the eye. But they are there and they are apparently ubiquitous, with concentrations in the trash vortex reaching 5.1 kg per square km*. That’s equivalent to about 200 1L bottles. Dissolved. Invisible to the eye. But present and dictating the chemistry of the ocean.

More recently, colleagues at Plymouth, Southampton and elsewhere illustrated the widespread occurrence of rubbish, mainly plastic, on the ocean floor. Their findings did not surprise deep sea biologists nor geologists; we have been observing our litter in these supposedly pristine settings since some of the first trips to the abyss.

My first submersible dive was on the Nautile, a French vessel that was part of a joint Dutch-French expedition to mud volcanoes and associated methane seeps in the Mediterranean Sea. An unfortunate combination of working practice, choppy autumn seas and sulfidic sediments had made me seasick for most of the research expedition, such that my chance to dive to the seafloor was particularly therapeutic. The calm of the deep sea, as soon as we dipped below the wave base, was a moment of profound physical and emotional peace. As we sank into the depths, the light faded and all that remained was the very rare fish and marine snow – the gently sinking detritus of life produced in the light-bathed surface ocean.

As you descend, you enter a realm few humans had seen…. For a given dive, for a given locale, it is likely that no human has preceded you.

Mud volcanoes form for a variety of reasons, but in the Mediterranean region they are associated with the tectonic interactions of the European and African continents. This leads to the pressurised extrusion of slurry from several km below the bottom of the sea, along mud diapirs and onto the seafloor. They are commonly associated with methane seeps; in fact a focus of our expedition was to examine the microbes and wider deep sea communities that thrive when this methane is exposed to oxidants at the seafloor – a topic for another essay. In parts of the Mediterranean Sea, they are associated with salty brines, partially derived from the great salt deposits that formed in a partly evaporated ocean about five and a half million years ago.

And all of these factors together create an undersea landscape of indescribable beauty.
On these mud volcanoes are small patches, about 20 cm wide, where methane escapes to the seafloor. There, methane bubbles from the mud or is capped by thick black, rubbery mats of microorganisms. Ringing these mats are fields of molluscs, bouquets of tube worms, great concrete slabs of calcium carbonate or white rims of sulphide and the bacteria thriving on it. Streaming from these seeps, down the contours of the mud cones, are ribbons of ultra-dense, hypersaline water. The rivulets merge into streams and then into great deep sea rivers. Like a photonegative of low-density oil slicking upon the water’s surface, these are white, high-density brines flowing along the seafloor. Across the Mediterranean Sea, they pool into beautiful ponds and in a few very special cases, form great brine lakes.

And two kilometres below the seafloor, where humans have yet to venture our rubbish has already established colonies. Plastic bottles float at the surface of these lakes; aluminium cans lie in the mud amongst the microbial mats; between those thick slabs of calcium carbonate sprout colonies of tube worms and the occasional plastic bag.

Image from Nautile Dive to the Mediterranean seafloor. Shown are carbonate crusts that form where methane has escaped to the seafloor as well as tube worms thriving on the chemical energy available in such settings. Plastic debris has been circled in the upper right corner.

We have produced as much plastic in the past decade as we have in the entirety of the preceding human history. But the human impact is not new. On our very first dive, we observed a magnificent amphora, presumably of ancient Greek or Roman origin and nearly a metre across, half buried in the mud.

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Today the human footprint is ubiquitous. Nearly 40% of the world’s land is used for agriculture – and over 70% of the land in the UK. Another 3% of the land is urbanised. A quarter of arable land has already been degraded.

There are outstanding contradictions and non-intuitive patterns that emerge from a deeper understanding of this modified planet. Pollinators are more diverse in England’s cities than they are in our rural countryside. One of the most haunting nature preserves on our planet is the Demilitarized Zone between North and South Korea – fraught with landmines but free from humans, wildlife now dominates. And of course, although global warming will cause vast challenges over the coming centuries, that is largely due to one human impact (greenhouse gas emissions) intersecting with another (our cities in vulnerable, low-lying areas and our borders and poverty preventing migration from harm). And on longer timescales, we have likely spared our descendants of 10,000 years from now the hassle of dealing with another Ice Age.

Glyptodon, source Wikipedia

But there can be no doubt or misunderstanding – we have markedly changed the chemical composition of our atmosphere. Carbon dioxide levels are higher than they have been for the past 800,000 years, perhaps the last 3 million years. It is likely that the last time the Earth’s atmosphere contained this much carbon dioxide, glyptodons, armadillo-like creatures the size of cars, roamed the American West, and hominids were only beginning the first nervous evolutionary steps towards what would eventually become man. Methane concentrations are three times higher than they were before the agricultural and industrial revolutions. Also higher are the concentrations of nitrous oxides. And certain chlorofluorcarbons did not even exist on this planet until we made them.

The manner in which we have changed our planet has – at least until now – allowed us to thrive, created prosperity and transformed lives in ways that would have astonished those from only a few generations in the past. It is too soon to say whether our collective impact has been or will be, on the whole, either ‘good’ or ‘bad’ for either the planet or those of us who live upon it. It will perhaps never be possible to define such a complex range of impacts in simple black and white terms. But there is no doubt that our impact has been vast, ubiquitous and pervasive. And it is dangerous to underestimate even momentarily our tremendous capacity to change our planet at even greater rates and in even more profound ways in the future.

*Moore, C.J; Moore, S.L; Leecaster, M.K;
Weisberg, S.B (2001). “A Comparison of Plastic and Plankton in the North
Pacific Central Gyre”. Marine
Pollution Bulletin 42 (12): 1297–300. doi:10.1016/S0025-326X(01)00114-X. PMID 11827116.

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

Prof Rich Pancost