By Samar Khatiwala
The concentration of CO2 in the atmosphere at the last ice age, some 19,000 years ago, was about a third lower than just prior to the Industrial Revolution. Where this carbon was stored during that frozen time is a mystery scientists have long sought to solve.
Most explanations for this “missing” CO2 – equivalent to about 200 billion tons of carbon or 20 years’ worth of anthropogenic emissions – have focused on the ocean. The reason is that, owing to some rather peculiar chemistry, CO2 is highly soluble in seawater. Consequently, the ocean contains roughly 60 times more CO2 than the atmosphere.
Illustration of the two main mechanisms identified by this study to explain lower atmospheric CO2 during glacial periods. Left: present-day conditions; right: conditions around 19,000 years ago during the Last Glacial Maximum.
Credit: Illustration by Andrew Orkney, University of Oxford.
In the way that a chilled glass of sparkling wine will remain fizzier for longer than a warm one (solubility increases with decreasing temperature), more CO2 must have been dissolved in the ocean during the last ice age when the ocean was on average 2.5ºC cooler. But previous studies, which essentially treated the ocean as a large tub of fizzy wine, have concluded that this mechanism can only explain about a quarter of the CO2 change. So what else is going on?
Well, we know that the ocean is (sadly!) not like a glass of Prosecco. Currents at the surface move water from the tropics to high latitudes. Along the way the water absorbs CO2 from the atmosphere as it cools, until it become dense enough to sink into the deep, taking dissolved carbon with it. This process is called the “solubility pump” since it is akin to “pumping” carbon down from the surface into the interior.
The pump doesn’t operate at full capacity, though, as the rate of absorption is quite slow and when the water sinks it actually contains much less CO2 than it is theoretically capable of absorbing from the atmosphere.
The more the water has to cool during its poleward journey, the greater the deficit. Reconstructions of sea surface temperature suggest that this gradient was smaller during the last ice age, with more cooling at mid-latitudes and less in polar regions, where the water is already close to freezing.
This led us to hypothesize that earlier studies, which had not only neglected this “disequilibrium” effect but also assumed that the ocean cooled uniformly, may have underestimated the effect of temperature.
To test this idea we developed a novel computer model which both accounts for disequilibrium and reproduces the reconstructed, non-uniform pattern of sea surface temperature change. Sure enough, the model predicts almost double the CO2 absorption as previous estimates and suggests that temperature can explain as much as half the glacial-interglacial atmospheric CO2 change.
In addition, ocean biology also plays a critical role in carbon storage. Like plants on land, marine algae absorb CO2 from the atmosphere during photosynthesis. When they die they sink into the deep ocean where bacteria feed on them to respire CO2 that then dissolves into the seawater. This “biological pump” doesn’t operate at full capacity either, as in large parts of the ocean algae are starved of iron (think of Popeye without his spinach!), an essential micronutrient supplied primarily by wind-borne dust.
As glacial periods were likely windier and dustier, more iron may have been supplied during those times, “fertilizing” algal growth and drawing down atmospheric CO2. But earlier studies had concluded that this could only account for about a tenth of the full CO2 change. Our new simulations informed by recent data on glacial dust fluxes can, on the other hand, explain a much more hefty quarter of the “missing” CO2.
If it’s true that these processes which were previously considered insignificant, are the biggest drivers of glacial-interglacial CO2 change, it’s perhaps even more surprising that the two processes widely believed to be the most important turn out to be minor players.
The current consensus is that a slowdown in the “overturning” circulation in the Atlantic and massive expansion of sea ice off Antarctica were the likely drivers of the CO2 change. However, our simulations show that if anything, both of these make the biological pump less efficient during glacial periods and thus increase atmospheric CO2!
Exciting as these new results are, their real significance lies in illuminating and untangling the complex interactions and feedbacks between the various processes that make up the ocean carbon cycle. Plenty more research will be needed before the final word on the cause of ice ages is written!
Read the full paper: Air-sea disequilibrium enhances ocean carbon storage during glacial periods in Science Advances.
Samar Khatiwala is Professor of Earth Sciences at the Department of Earth Sciences, University of Oxford. Find out more.
By Kevin Grecksch
Whenever I start a presentation about water governance, I ask the audience if they know what the price of a litre of tap water is. Usually the room goes quiet, shoulders shrug and only a few make a guess, usually an overestimation. My next question is about the price of a litre of petrol. Within a split second, I get the right answer from the audience.
Water is indispensable, not only for humans, but for all living things. Yet our relationship with water is out of touch. In developed countries, drinking water is readily available everywhere: from the tap, the supermarket, and the corner shop. Most of us take water for granted; many do not realise just how important water really is and what we use it for. Besides drinking water, water is used in production processes, both industrial and in the food and drinks sector. We trade water in reality and virtually, we regulate water, we divert water, we pollute water, we fight over water, we rely on water to cool thermal power plants, and most importantly, water will be the medium through which climate change impacts are felt and experienced. Water can also be a threat. Floods and droughts endanger and destroy livelihoods, kills people and animals, and contributes to the spread of vector-borne diseases.
Water is an important issue, if not the most important, yet at the same time it cannot be singled out as it is part of the wider environmental story. That story tells us about the interdependencies and links between water and other sectors, such as agriculture, energy, forestry, manufacturing, and waste disposal. For example, a simple daily routine such as a hot shower involves not only the public water supply, but also relies on electricity or gas to heat up the water. Furthermore, water is a highly social issue. It is humans who make decisions about water, and who gets it and how much.
Sustainable water governance is therefore a precondition for successful climate change adaptation. Water governance describes the steering, coordination and decision-making processes of actors to govern water. This includes laws, regulations, public participation and education. A diversity of actors – policy makers, regulators, water companies, non-governmental organisations and consumers – have a role in this process. This differs from jurisdiction to jurisdiction, and legacies and path dependencies play a major role in how public water supply is institutionalised in a country.
Water governance faces challenges such as population growth, rapid urbanisation and land use changes. Climate change and its projected effects will exacerbate this. Some regions will have more water, and others less. Increasing populations will lead to questions about access and allocation. A key issue is uncertainty: we simply do not know if and when the projected effects of climate change will happen, and to what extent.
In the context of climate change, the term ‘adaptive water governance’ is frequently used. What this means is that water governance needs to be flexible in order to adapt to uncertainties. Legislation and policies should not be set in stone, but reviewed at regular intervals to account for the latest research results or practical experiences. In some cases we need to be able to overcome current water policies and opt for new approaches. Cape Town’s threat of a “day-zero” in 2018, where all taps would be turned off, led to drastic policy changes, which subsequently led to massive reductions in daily water consumption by the general public and businesses.
Flexibility also means to cater for the different projected impacts of climate change across the world. This includes taking into account geographical, regional, social and cultural characteristics, and should result in tailor-made adaptation strategies. Public participation from the very beginning of a process, and not just to legitimise the outcome, should be an inherent part of adaptive water governance. Unfortunately, the latter is also one of the greatest challenges. Who are the stakeholders who should take part? Do they have enough staff and financial resources at their disposal?
Another key issue to overcome is the “silo-mentality” we still find in environmental governance. While the scientific consensus is clear about the need to look at an issue like water in an integrated way, in reality we often find a “silo-mentality”. This refers to the non-collaboration across policy sectors, for instance among water, urban planning, agriculture and energy. Even within water governance, we often find that flooding and drought policy teams operate separately from each other and are not looking at the issue from an integrated perspective.
Water governance is a challenging task, but there are many positive and promising examples, policies, and approaches available. Some great examples are the catchment-based-approaches, which look at a river catchment as a whole. Or in the Netherlands we find “water-squares”, public places shaped like a bath tub that function both as a playground and as a retention area for overflow water after a heavy rain event. It is those co-benefits, being good for climate change adaptation as well as fulfilling another function such as recreation, creating jobs, or restoring wildlife, that are key.
We do not only drink water, but we swim in water, we sail or row on water, we walk along rivers, canals and lakes. We cherish water in various ways, but often neglect its social and cultural value at the same time. Tackling this is a key challenge for water governance in the future.
Kevin Grecksch is a British Academy Postdoctoral Fellow at the Centre for Socio-Legal Studies in the Faculty of Law. He is a social scientist who specialises in water governance and climate change adaptation.
Professor John Goodenough from the Cockrell School of Engineering at The University of Texas at Austin has been awarded the Royal Society’s Copley Medal, the world’s oldest scientific prize. Already a fellow of the Royal Society, Goodenough is being honoured for his exceptional contributions to materials science, including his discoveries that led to the invention of the rechargeable lithium battery—used in devices like laptops and smartphones worldwide.
As the latest recipient of the Royal Society’s premier award, Professor Goodenough joins an elite group of men and women, such as Benjamin Franklin, Charles Darwin, Louis Pasteur, Albert Einstein and Dorothy Hodgkin, who have been awarded the Copley Medal for their exceptional contributions to science and engineering in the past.
Venki Ramakrishnan, President of the Royal Society, said, “Professor Goodenough has a rich legacy of contributions to materials science in both a fundamental capacity, with his defining work on the properties of magnetism, to a widely applicable one, with his ever-advancing work on batteries, including those powering the smartphone in your very pocket. The Royal Society is delighted to recognise his achievements with the Copley Medal, our most prestigious prize.”
On hearing the news, Professor Goodenough said, “Words are not sufficient to express my appreciation for this award. My ten years at Oxford were transformative for me, and I thank especially those who had the imagination to invite a U.S. non-academic physicist to come to England to be a Professor and Head of the Oxford Inorganic Chemistry Laboratory. I regret that age and a bad leg prevent my travel back to England to celebrate such a wonderful surprise.”
Professor Goodenough is currently serving as the Virginia H. Cockrell Centennial Chair in Engineering at The University of Texas at Austin, where he continues to work on new battery technology. Though his lithium-ion breakthrough provided a reliable, rechargeable battery, it is, at the same time, weak, expensive and flammable—shortcomings Professor Goodenough aims to overcome with his latest work on solid-state batteries.
Innovations in battery technology, such as the lithium-ion-based model, helped liberate society from its reliance on cables. Professor Goodenough now aims to develop technology with an even bolder end goal: to liberate society from its dependence on fossil fuels.
He began his research career in 1952 at the Massachusetts Institute of Technology’s (MIT) Lincoln Laboratory where he was part of a team that developed random-access magnetic memory (RAM) – a technology still used in digital computing. Building on this experience, he authored ‘Magnetism and the Chemical Bond’, a treatise and modern-day classic textbook on the behaviour of magnetic interactions. He helped lay the foundations for developing a set of rules for predicting signs of super-exchange interactions in solids, known as the Goodenough-Kanamori rules.
After his time at MIT, Professor Goodenough led the University of Oxford’s Inorganic Chemistry Laboratory. His research focused on the implementation of lithium as a potential cathode material for batteries – pioneering work that was to form the basis for the first commercial lithium-ion battery, still used in mobile electronics all around the world. In 1986 his curiosity and expertise drew him to a position at the Cockrell School of Engineering at UT Austin, where he has remained ever since.
The Copley Medal was first awarded by the Royal Society in 1731, 170 years before the first Nobel Prize. It is awarded for outstanding achievements in scientific research. In recent years, recipients include eminent scientists such as Peter Higgs, the physicist who hypothesised the existence of the Higgs Boson, as well as DNA fingerprinting pioneer Alec Jeffreys, and Andre Geim, who discovered graphene. Last year’s winner, Professor Jeffrey Gordon, was honoured for his contributions to understanding the role of gut microbial communities to human health and disease.
A study published today by Dr Beth Mortimer and colleagues at the Department of Zoology and University Carlos III of Madrid reveals that orb weaving spiders can compare 3D vibrational inputs into their 8 legs from the web to locate prey.
Watch a spider catch its prey:
Dr Mortimer found that as vibrations spread from prey through a spider’s orb web, the information on prey location becomes available by comparing 3D motion across the spiders’ eight legs.
Using computer models of orb webs, the researchers investigated whether web vibration contains information on the location of a vibration source for spiders that directly and remotely monitor web vibration.
They found that comparisons of 3D vibration magnitude across eight legs (direct monitoring) allowed them to determine vibration source distance and direction, which was not possible with a remote monitoring strategy.
The researchers concluded that specific web features which are under the control of spiders that promote the transfer of localisation information.
Read the full paper: ‘Decoding the locational information in the orb web vibrations of Araneus diadematus and Zygiella x-notata’ in Journal of the Royal Society Interface
Until September BBC Gardeners’ World magazine is running a monthly feature ‘Grow Yourself Healthy’. The May issue focuses on how gardens and gardening can improve sleep, and featured Julie Darbyshire, researcher for the University of Oxford Critical Care Research Group (Nuffield Department of Clinical Neurosciences), alongside other sleep researchers and experts, discussing the benefits of gardening ahead of the RHS flagship flower show in Chelsea.
If you’re not tired, you’re not going to fall asleep. It is perhaps obvious when you think about it, but many of us don’t. We all know we should have 30 minutes of exercise every day but with today’s hectic lifestyle many of us struggle to find the time. Thankfully, for the gym-phobic amongst us with memories of wet and cold cross-country days across the muddy school playing field, exercise needn’t be always about running, or going to the gym. Ever tried digging over a flower bed or veg plot? Gardening can be a great way to achieve an all-body workout. It can also be a low-impact path to being a little bit more active. Some gentle pottering in the garden (beneficial in itself) can lead to other tasks, which leads to more physical exertion, which can only ever be a good thing... But physical exercise is not the only way that gardening can help you sleep at night.
Sleep is hugely influenced by your natural circadian rhythm. Every cell in the human body has a clock that’s controlled by the suprachiasmatic nucleus (SCN) in the brain. The SCN is linked directly to the eyes. Light then, is a key driver to circadian control. Research has demonstrated if you put people into dark places with no external clues to the time of day, their circadian rhythms will become abnormal very quickly. The body needs appropriate exposure to daylight to regulate the body’s responses to help ‘reset’ this clock and keep you “on time”. Many of us spend the majority of the day inside. Light levels in an office, even close to a window, will be far below those of bright natural daylight which is around 20,000 lux. The spectrum of light inside is also quite different. Natural daylight is quite ‘blue’ (5000-6500K) and the body expects a change to more orange/red tones as the day fades to night. This is one of the reasons why ‘screen time’ in the evening isn’t good when you are supposed to be preparing for sleep. The light entering the eyes is too blue for the time of day. Spending the majority of the day inside where light levels are both low (lux levels around 150 are not uncommon) and often in the ‘warmer’ spectrum range (<3000K) is biologically confusing. Getting outside, getting a bit out of breath, and even being a bit chilly, are the best ways to regulate your body clock.
The Critical Care Research Group at the University of Oxford has been exploring how the hospital environment influences the patients’ experiences of their admission. As part of a research project (SILENCE) that was funded by the National Institute of Health Research (Research for Patient Benefit, ref: PB-PG-0613-31034), the group has been studying sleep patterns in patients admitted to the intensive care unit (ICU). The results of the SILENCE sleep study have been published in the Journal of the Intensive Care Society. Julie Darbyshire, lead researcher on the project, was also interviewed about the study for a critical care focused podcast series.
The research team used several different ways to electronically measure sleep and also asked patients and their nurses who were looking after them overnight to complete a questionnaire. All methods of sleep measurement confirmed that sleep was poor. Most patients were able to sleep for at least some of the time but the average total sleep overnight was just over two hours. This is a long way short of the seven to eight hours sleep that is recommended for most adults. The team also found that the average time a patient in the ICU can expect to be asleep before awakening is just one minute. This can leave patients exhausted by the end of the night and many feel that they haven’t slept at all.
Professor Duncan Young, senior clinical lead for the Critical Care Research Group and honorary NHS consultant in anaesthetics and intensive care medicine, said: ‘Patients clearly struggle to sleep well when in intensive care. Sleep deprivation likely leads to confusion, and confusion is thought to complicate the healing process and slow recovery. The real challenge is knowing what to do to improve things for patients.’
Julie says: ‘Patients may be offered earplugs and eye masks to help them sleep, but not everyone likes wearing them. Improving the environment has to be the better approach. This should include reducing sound levels, making sure that patients have access to plenty of natural light during the day, and turning lights off overnight.'
Julie also suggests that having access to the outside is likely to benefit patients recovering from their critical illness. Early hospital environment work by Robert Ulrich in the 1980s showed that patients who could see trees outside went home sooner and experienced lower levels of pain than those patients who could only see a wall. More recent studies suggest that access to a garden during a hospital stay can lower stress levels in both patients and their families. Recognising this, Horatio’s Garden is a charity that creates and builds accessible gardens for NHS spinal injury units and a number of hospitals around the UK have gardens where they can take their ICU patients during the day.
The team in Oxford has been able to show how different sleep in the ICU is when compared to normal healthy adult sleep patterns. As well as being awake for much of the night, patients in the ICU experience almost no rapid eye movement (REM) sleep, or deeper, restful sleep. This means that even when patients do sleep in the intensive care unit, their sleep is poor quality. Healthy sleep would include about 20% of REM sleep and about 20% of deep sleep. Good quality sleep is vital for preservation of the immune function, recovery, and can help prevent delirium which is a common problem for patients in the intensive care unit. Persistent poor sleep may also lead to longer-term cognitive and mental health problems. It has recently been reported that patients struggling to cope mentally after their critical illness can also experience worsening physical health .
Gardening is, in and of itself, a positive, forward-looking activity. After all, no-one plants carrot seeds without expecting to eat carrots in the future! The Kings Fund report on Gardens and Health (2016) highlights some of the mental health benefits to just being in a natural environment, GPs in Scotland are working with the Royal Society for the Protection of Birds to offer ‘nature prescriptions’ in Shetland, and the Royal Horticultural Society (RHS) has teamed up with GPs across the UK as part of a new ‘social prescribing’ scheme. The University of Oxford Gardens, Libraries and Museums (GLAM) project for well-being is looking at this in more detail. Researchers from the Centre for Evidence Based Medicine (Nuffield Department of Primary Care Health Sciences) are working with GLAM to promote knowledge exchange, raise awareness, and to add to the evidence base to support wider implementation of social prescribing.
This year’s Chelsea Flower Show has a strong focus on the health benefits of interacting with nature. Many of the show gardens feature gardening for resilience, recovery, and wellbeing. So if you’re struggling to sleep at night, go outside during the day, plant some seeds, prune something, dig the borders, enjoy the fresh air and the sunshine, and reap the rewards of a good night’s sleep.
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