carbon dioxide – Page 2 – Cabot Institute for the Environment blog

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

Materials and energy… over a pint?

Posted on May 30, 2014April 14, 2023 by janet.crompton

Bristol, along with 20 other cities, in 6 different countries, was host to an interesting approach to science communication – over three nights, 19 – 21 May 2014, science took place at the pub!

Although varied, relevant and interesting research takes place every day at Universities, in many cases the general public is completely unaware of what goes on inside them – other than lectures and exams! Pint of Science is a volunteer-based, not-for-profit festival, which takes academic research into the everyday world, by having scientists at the pub sharing their work and answering questions.

Premièring this year in Bristol, the festival was well received, with many of the events sold-out before the doors were even opened. Across the city, four pubs opened their doors to a curious audience looking to learn about a range of topics from nanotechnology, to energy, to the brain and oceans or volcanoes.

Engaging society being at the heart of the Cabot Institute’s aims, it was quick to become involved when approached. As well as sponsoring the event, the Institute was well represented by two of its members, Professors David Fermín and Paul Weaver, who shared their research during the festival.

Energy, Materials and the Electrochemist Dream

L-R David Parker and David Fermin

Prof David Fermín and one of his PhD students, Mr David Parker, took on the second evening of the festival, talking about “Energy, Materials and the Electrochemist Dream”. During this event renewable energy sources, in particular solar, were championed. Of interest was the many ways in which solar energy can be harvested and used, whether to be directly converted into electricity or used to produce “solar fuels” from water or carbon dioxide. The need for developing new photovoltaic materials, which are cheap, efficient and made from abundant elements, was stressed. Questions from the public revolved about “how green” these technologies really are and the need to develop a “complete, systematic” approach to energy, which can incorporate various forms and sources of energy. This last is another key interest of the Institute, with groups in Bristol doing interesting work in this area.

Morphing cars, planes and wind turbines: the shape of things to come

Paul Weaver talks to the pub-goers

On the festival’s last evening, Prof Paul Weaver and one of his PhD students, Eric Eckstein, talked about “Morphing cars, planes and wind turbines: the shape of things to come”. They discussed the development of new composite materials with the ability to tailor structural properties and the difficulties involved in predicting responses. Also highlighted was the very important interaction and synergy between University and Industry in this field. In a particularly interactive approach they brought along many of the composite materials they work with, alongside demonstrating the strength and failure of various materials, allowing the public to see and feel how different properties can be altered. The use of composite materials in wind turbines and helicopter blades was of particular interest and generated an animated discussion on the subject.

This blog was written by Cabot Institute members Daniela Plana (Chemistry) and Matt Such (ACCIS) at the University of Bristol.

Climate lessons from the past: Are we already committed to a warmer and wetter planet?

Posted on February 17, 2014April 19, 2023 by janet.crompton

Last September, the Cabot Institute and the University of Bristol hosted the 2nd International Workshop on Pliocene Climate. Following on from that, we have just released a short video describing what the Pliocene is and its relevance for understanding climate change.

The Pliocene is a geological time interval that occurred from 5.3 to 2.6 million years ago. This interval of Earth history is interesting for many reasons, but one of the most profound is that the Earth’s atmosphere apparently contained elevated concentrations of carbon dioxide – in fact, our best estimates suggest concentrations were about 300 to 400 ppm, which is much higher than concentrations of 100 years ago but lower than those of today after a century of intensive fossil fuel combustion.

Image by NASA

Consequently, the Pliocene could provide valuable insight into the type of planet we are creating via global warming. Our video release happens to coincide with pronounced flooding across the UK and focussed attention on our weather and climate. There is little doubt that increased carbon dioxide concentrations will cause global warming; instead, the key questions are: how much warming will there be and what are the consequences of that warming? One way to study that is to examine previous intervals of Earth history also characterised by high carbon dioxide concentrations. The comparisons are not perfect, of course; for example, during the Pliocene the continents were in roughly but not exactly the same positions that they are in today. But it can serve as another piece of the puzzle in predicting future climate.

One of the key lessons from Earth history is climate sensitivity. Climate sensitivity can be expressed in various ways, but in its simplest sense it is a measure of how much warmer the Earth becomes for a given doubling of atmospheric carbon dioxide concentrations. This is well known for the Pleistocene, and especially the past 800,000 years of Earth history, an interval with detailed temperature reconstructions and carbon dioxide records from ice core gas bubbles. During that time, and through multiple ice ages, climate sensitivity was about 2.5 to 3°C warming for a doubling of carbon dioxide, which is in the middle of the model-based range of predictions.

Ice core sampling.
Image by NASA ICE (Ice Core Vitals) [CC-BY-2.0]
Wikimedia Commons

Ice core records, however, extend back no more than a million years, and this time period is generally characterised by colder climates than those of today. If we want to explore climate sensitivity on a warmer planet, we must look further back into Earth history, to times such as the Pliocene. Reconstructing atmospheric carbon dioxide concentrations in the absence of ice cores is admittedly more challenging. Instead of directly measuring the concentration of carbon dioxide in gas bubbles, we must rely on indirect records – proxies. For example, carbon dioxide concentration influences the number of stomata on plant leaves, and this can be measured on ancient leaf fossils. Alternatively, there are a number of geochemical tools based on how carbon dioxide impacts the pH of seawater or how algae assimilate carbon dioxide during photosynthesis; these are recorded by the chemical composition of ancient fossils.

These estimates come with larger error bars, but they provide key insights into climate sensitivity on a warmer Earth. Recent research indicates a convergence of Pliocene carbon dioxide estimates from these various proxies and gives us more confidence in deriving climate sensitivity estimates. In particular, it appears that an increase of carbon dioxide from about 280 parts per million (the modern value before the industrial revolution) to about 400 parts per million in the Pliocene results in a 2°C warmer Earth. Accounting for other controls, this suggests a climate sensitivity of about 3°C, which confirms both the Pleistocene and model-based estimates.

It also suggests that we have yet to experience the full consequences of the greenhouse gases already added to the atmosphere.

So then, what was this much warmer world like? First of all, it was not an inhospitable planet – plants and animals thrived. This should not be a surprise; in fact, the Earth was much warmer even deeper into the past. The climate change we are inducing is a problem for humans and society, not our planet.

However, the Pliocene was a rather different world. For example – and importantly, given current events in the UK – these higher global temperatures were associated with a climate that was also wetter* than present. That provides important corroborating evidence for models that predict a warmer and wetter future.

Image by w:en:User:Ivan and licensed as GFDL

Perhaps most striking, sea level appears to have been between 10 to 40 metres higher than today, indicating that both the Greenland Ice Sheet and Antarctic Ice Sheet were markedly smaller. To put that into context, the Met Office has already commented on how flooding in the UK has been and will be exacerbated by sea level rise of 12 centimetres over the last 100 years and a further 5 to 7 centimetres by 2030.

We must be careful in how we extract climate lessons from the geological record, and that is particularly true when we consider ice sheet behaviour. One widely discussed concept is ice sheet hysteresis. This is a fancy way of saying that due to feedback mechanisms, it could be easier to build an ice sheet on Greenland or Antarctica than it is to melt one. If such hysteresis does stabilise our current ice sheets, then we should not assume a planet with 400 ppm of carbon dioxide will necessarily have sea level 20 metres higher than that of today. But if hysteresis is rather weak, then the question is not whether we will see massive sea level change but rather how long it will take (Note: It is likely to take centuries or millennia!).

Most importantly, the collective research into Earth history, including the Pliocene, reveals that Earth’s climate can change. It also reveals that climate does not just change randomly: it changes when forced in relatively well understood ways. One of these is the concentration of carbon dioxide in our atmosphere. And consequently, there is little doubt from Earth history that transforming fossil carbon into carbon dioxide – as we are doing today – will significantly impact the Earth’s climate system.

* See Brigham-Grette, J., Melles, M., Minyuk, P., Andreev, A., Tarasov, P., DeConto, R., Koenig, S., et al., 2013. Pliocene Warmth, Polar Amplification, and Stepped Pleistocene Cooling Recorded in NE Arctic Russia. Science 340 (6139), 1421-1427. doi: 10.1126/science.1233137 and Salzmann, U., Haywood, A.M., Lunt, D.J., 2009. The past is a guide to the future? Comparing Middle Pliocene vegetation with predicted biome distributions for the twenty-first century. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 367 (1886), 189-204.

This blog is by Prof Rich Pancost, Director of the Cabot Institute. Rich will be giving a public lecture on how biogeochemical cycles have regulated the global climate system throughout Earth’s history on 25 February in Bristol. The event is free and open to all, do come along to learn more.

To learn more about the Pliocene – and palaeoclimate research, in general – you can watch Professor Gerald Haug’s public lecture, Climate and Societies, recorded at the Cabot Institute as part of the 2nd International Workshop on Pliocene Climate.

Prof Rich Pancost

How the UK government is tackling climate change – a good plan or on course for disaster?

Posted on February 8, 2014April 19, 2023 by janet.crompton

Steve Smith, a researcher working for the government’s independent advisors, the Committee on Climate Change (CCC), came to visit the Cabot Institute on 7 February 2014. His talk was about whether the UK is on course for tackling climate change, or rather, the UK is on course for meeting its 2050 target of 80% reduction in carbon emissions. It was a real eye opener. Here I summarise the talk and the main points made by Steve. All figures taken from Steve’s talk.

Background

The CCC consists of several high profile board members, including Lord Deben, Sir Brian Hoskins, and Lord Krebs amongst others. As a group, their role on the mitigation side is to independently advise the government on UK emission targets. The UK is legally bound to meet the 2050 target of 80% reduction of CO2 emissions below 1990 levels. Being legally bound to this commitment means the government has to meet this target. Steve wasn’t quite sure what the implications would be if the UK government broke the law by not meeting the emissions target by 2050. [Update: the EU has now agreed to a 40% reduction in emissions by 2030].

Extreme weather events will become
more common

The current risk of impacts from climate change are set out in the latest IPCC reports. It is agreed that 2 degrees of warming will exacerbate current climate-related impacts such as increased risk of floods, drought, food insecurity, human displacement, plant and animal disease, etc but that technological advances and human resilience should be able to live with this. Beyond 4 degrees rise many systems will just not be able to adapt – a blunt warning if there ever was one.

The current 2050 target of 80% reduction of emissions keeps it in line with a 2 degree warming scenario. This equates to approximately 20 – 24 GT CO2 Kyoto emissions by 2050, which itself implies that each person living on the planet in 2050 will only contribute 2 tonnes of CO2 per year. This is a similar figure to 6000 miles in your car (an easy annual commuting amount). Steve pointed out that the total emissions from electricity in 2010 were almost the same amount as total emissions that will be allowed in 2050. This is not a joke, we will have to meet these targets and we will have to severely cut our carbon emissions. So what I want to know is what’s the plan?

What is the government doing?

It seems the government does have a plan and it has had a plan for a few years now. A long and winding road sort of plan (it stretches 40 years and Steve also admitted that the plan is likely to change over that time period), but it’s a plan nonetheless with a hopeful outcome. Currently the government looks at reducing CO2 emissions by implementing cost effective measures across the economy. Examples include increased implementation of electrification and Carbon Capture and Storage (CCS) within industry, and district heating and air source heat pumps for buildings.

Nuclear power could
help decarbonise the UK

Looking at one of these key measures in more detail, electrification, it is vitally important to not only increase reliance on electricity as a power source (rather than gas or oil) but also to decarbonise electricity production, producing a win-win situation. The government aims to do this in steps. The first step is the decarbonisation of base load electricity production into the 2020s. Base load electricity is the minimum amount of power made to meet minimum demands from users. Increasing nuclear power could play a big part in this transition. From the 2020s onwards, the government will aim to decarbonise peak electricity, the stuff that’s needed on-demand like when we switch on our kettles during an ad-break. The timescales do seem quite long but it takes around 9 years to build a nuclear power station, so put it in perspective the timings aren’t actually that long. However it is questionable whether we can actually wait until 2050 to become decarbonised for fear of hitting that 4 degree global temperature rise in the meantime.

Decarbonising electricity is one of the most useful things the government can do especially as most fossil fuel driven machines can be electrified – including our cars. Steve admitted there was one area that was proving difficult to decarbonise – the aviation and shipping sector. The CCC are still working out how to make this area more efficient as it is a really difficult sector to change.

What are the costs to the UK economy?

The CCC estimates that the resource cost of reducing CO2 from all sectors would amount to 0.5% GDP. If there was a scenario in the future of high fuel prices, this cost would drop to 0.1% GDP, but if fuel prices came down we would pay more – around 0.8% GDP. Rather interestingly, 0.6% of costs of reducing CO2 fall in the power sector. So should the government put up the cost of fuel to reduce the resource cost to the UK as a whole? It’s not as clear cut as that. Fuel poverty and economic competitiveness are huge issues which need to be carefully considered before any price hikes.

The CCC is confident that all government projections will be wrong by 2050. To counter this the CCC have come up with some bottom up scenarios – Max (decarbonise everything), Stretch (optimistic carbon reduction but not ideal), Barrier (the most likely scenario but the worst for CO2 savings). By mixing and matching these scenarios across all sectors as appropriate, multiple scenarios have been created and it is from these multiple scenarios that the CCC can keep resource cost below 1% GDP for the UK.

How are we doing so far?

We’re doing well to decarbonise our cars.
Image by Danrok, Wikimedia Commons

From the first period 2008 – 2012, the first carbon budget was met. Greenhouse gas emissions were reduced. However, the main cause of this has been attributed to the recession and only 1% of emission reduction was from low carbon energy measures.

The good news is that the UK is ahead of schedule on the decarbonisation of cars. However we are falling behind on non-traded emissions such as cavity insulation. We are looking like we will be on target for the second budget (2013 – 2017) but not budgets 3 (2018 – 2022) or 4 (2023 – 2027). If the UK is to meet these targets then the government needs to improve future policies and speed up the rate of change to a decarbonised society.

Shale gas – a game changer?

The USA has kicked heavy emission coal off the system by investing heavily in shale gas (aka fracking) and in doing so has radically (and unwittingly) changed its climate policy. Steve questioned whether shale gas could be a game changer in the UK. Rather interestingly, it seems that not much extra gas will be produced in the UK by 2035 if shale gas was put into the mix. UK gas demand turns out to be significantly higher than what the UK can actually produce (including that from shale). Questions then arise, for example, if you are offsetting imports of gas where are those imports coming from? How are they being transported? What amount of CO2 is being released in the process of transportation?

Methane leakage from shale gas is also a problem. The CCC have found that methane leakage from shale gas would be more beneficial to decarbonisation due to the overall emissions from shale gas being less than the amount of emissions from current transportation of Liquified Natural Gas (which has a much smaller amount of methane leakage and larger amount of emissions overall). Any reduction is better than no reduction and the government thinks that a well regulated shale gas industry could help the UK reach those decarbonisation targets.

A healthy low carbon diet

Image by Richard Croft, Wikimedia Commons

Decarbonising the UK is going to be tough but there are net benefits from doing so. One of these net benefits is health. Although it is difficult to quantify the health impact of all CO2 emission reducing methods, we can quantify those such as reducing congestion, improving air quality, and getting people on their bikes doing more exercise.

A question was asked of Steve at the end of the talk…why are we not efficient in all of these sectors already? Steve responded that people don’t act entirely rationally, that decarbonisation takes time to filter into people’s mindsets and that subsidies for the wrong sorts of fuels does not help.

So should the government do more to embed a low carbon mindset into its people and industry? Or should we be educating ourselves and personally reducing our own carbon emissions (the non-traded emissions)? Should we just demand more of our government, put the pressure on the policy makers and inspire current and future generations to do more and be more in a low carbon world? The CCC and the government doesn’t have all the answers. It’s up to research institutions, like the Cabot Institute, to put their collective heads together to develop solutions to help decarbonise society and to engineer new low carbon technologies, with support from government and industry.

The UK has become a lot more efficient since the 2050 targets were introduced, the government is legally bound to meet these targets so it is serious about the job in hand, and as a result its policies have been changing to reduce emissions. The government just has to ensure it continues to act on the CCC’s recommendations.

View the slides from Steve’s talk.

This blog was written by Amanda Woodman-Hardy, Cabot Institute Administrator, University of Bristol.

Follow @Enviro_Mand

Amanda Woodman-Hardy

Global carbon budget reveals dangerous footprints

Posted on November 20, 2013April 19, 2023 by janet.crompton

Carbon dioxide is the most important greenhouse gas produced by human activities, and one which is likely to cause significant global climate change if levels continue to increase at the current rates. This year’s Global Carbon Budget holds disappointing yet hardly unexpected news; in 2012, carbon dioxide (CO₂) emissions rose by 2.1% to the highest levels in human history, a total of 9.7 billion tonnes.

CDIAC Data; Le Quiere et al 2013. Global Carbon Project 2013. Data not adjusted for leap year.

The annual Carbon Budget report is compiled by the Global Carbon Project, a collaboration of 77 scientists from around the world including the Cabot Institute’s own Dr Jo House. They predict that in 2013, global carbon emissions will have increased by a further 2.1%, setting a new record high.

Major CO₂ emitters

China produced the most CO₂ in 2012 (27% of total), which was almost twice as much as the second worst offender, the USA (14%). The European Union (EU) contributed 10% of emissions. China’s emissions increased 5.9% between 2011 and 2012, whilst the USA and EU continued to decrease their CO₂ output (by 3.7% and 1.3% respectively).

CDIAC Data; Le Quiere et al 2013. Global Carbon Project 2013.

While developing nations like China and India have high levels of greenhouse gas emissions, it is important to note that per capita the USA has by far the highest emission rate at 4.4 tonnes of carbon per person per year (tC/p/yr). China has reached EU levels of 1.9 tC/p/yr, while India produces just 0.5tC/p/yr. Since the Industrial Revolution the USA and Europe still have the highest cumulative output of CO₂ from burning fossil fuels, something to consider before we become too self-righteous.

CDIAC Data; Le Quiere et al 2013. Global Carbon Project 2013.

Carbon sinks

Image by Manfred Heyde

Increased CO₂ emissions are absorbed by carbon sinks, specifically the atmosphere, the oceans and the land. On land, trees and other plants absorb around 27% of emitted CO₂ for photosynthesis, which results in more growth and eventually more carbon stored as leaf litter in the soil.

In the oceans, algae may absorb some CO₂ for photosynthesis (although not as much as was once hoped), but the water itself absorbs most of the 27% of CO₂ stored in the oceans. Unfortunately when carbon dioxide dissolves in water it can react to form carbonic acid, a leading cause of ocean acidification. Since the Industrial Revolution, oceans have become approximately 30% more acidic. If present trends continue, oceans will be 170% more acidic by 2100, a devastating change for shellfish and corals which rely on an alkaline calcium carbonate exoskeleton, and the other marine life that depend on these species.

The atmosphere absorbs the remaining 45% of CO₂ emissions. Over the past 250 years the atmospheric CO₂ concentration has risen from 227 parts per million (ppm) to an average of 393ppm in 2012. Back in May, the first CO2 reading of 400ppm was recorded, a significant milestone in the relentlessly increasing greenhouse gas levels. We are now on track to see a ‘likely’ 3.2-5.4°C increase in global temperature by 2100, causing severe droughts and desertification of agricultural land around the world and flooding of low lying coastal areas.

The Kyoto protocol

In 1992, 37 industrialised countries agreed to reduce their carbon dioxide emissions by an average of 5% below 1990 levels during the period of 2008 to 2012. The Global Carbon Budget reported that whilst some regions such as Europe did reduce their CO₂ output, other areas (eg. Asia, Africa, Middle East) doubled or even tripled their emissions, resulting in a net gain of 58% more CO₂ emissions in 2012 than in 1990.

The biggest CO₂ emitter, China, recently joined almost 200 other countries in agreeing to sign the pledge to reduce their carbon emissions at a summit in Paris in 2015. It is hoped that this climate change summit will follow on from the work started by the Kyoto protocol to reduce CO₂ emissions to a more sustainable level.

What’s your carbon footprint?

We are at a critical stage in history. The Global Carbon Budget suggests that we have already produced 70% of the carbon dioxide it is possible to emit without causing a significant and irreversible change to the planet’s climate. It is vital that all nations work together to reduce carbon emissions to a sustainable level, preventing a 2°C increase in global temperature.

If you would like to calculate your carbon footprint, visit the government’s carbon calculator.

This blog is written by Sarah Jose, Biological Sciences, University of Bristol

You can follow Sarah on Twitter @JoseSci

Sarah Jose

Will global food security be affected by climate change?

Posted on September 30, 2013April 20, 2023 by janet.crompton

The Intergovernmental Panel on Climate Change (IPCC) has just released an important report outlining the evidence for past and future climate change. Unfortunately it confirms our fears; climate change is occurring at an unprecedented rate and humans have been the dominant cause since the 1950s. Atmospheric carbon dioxide (CO₂) has reached the highest level for the past 800,000 years, which has contributed to the increased temperatures and extreme weather we have already started to see.

As a plant scientist, I’m interested in the complicated effects that increased temperatures, carbon dioxide and changes in rainfall will have on global food security. Professor David Lobell and Dr Sharon Gourdji wrote about some of the possible effects of climate change on crop yield last year, summarised below alongside IPCC data.

Increased CO₂

Plants produce their food in a process called photosynthesis, which uses the energy of the sun to combine CO₂ and water into sugars (food) and oxygen (a rather useful waste product). The IPCC reports that we have already increased atmospheric CO₂ levels by 40% since pre-industrial times, which means it is at the highest concentration for almost a million years. Much of this has accumulated in the atmosphere (terrible for global warming) or been absorbed into the ocean (causing ocean acidification) however it may be good news for plants.

Lobell and Gourdji wrote that higher rates of photosynthesis are likely to increase growth rates and yields of many crop plants. Unfortunately, rapid growth can actually reduce the yields of grain crops like wheat, rice and maize. The plants mature too quickly and do not have enough time to move the carbohydrates that we eat into their grains.

High temperatures

The IPCC predicts that by the end of the 21st century, temperatures will be 1.5C to 4.5C higher than they were at the start of it. There will be longer and more frequent heat waves and cold weather will become less common.

Extremely high temperatures can directly damage plants, however even a small increase in temperature can impact yields. High temperatures means plants can photosynthesise and grow more quickly, which can either improve or shrink yields depending on the crop species (see above). Lobell and Gourdji noted that milder spring and autumn seasons would extend the growing period for plants into previously frosty times of year allowing new growth periods to be exploited, although heat waves in the summer may be problematic.

Image credit: IPCC AR5 executive summary

Flooding and droughts

In the future, dry regions will become drier whilst rainy places will get wetter. The IPCC predicts that monsoon areas will expand and increase flooding, but droughts will become longer and more intense in other regions.

In flooded areas, waterlogged soils could prevent planting and damage those crops already established. Drought conditions mean that plants close the pores on the leaves (stomata) to prevent water loss, however this means that carbon dioxide cannot enter the leaves for photosynthesis and growth will stop. This may be partly counteracted by the increased carbon dioxide in the air, allowing plants to take in more CO₂ without fully opening their stomata, reducing further water loss and maintaining growth.

Image credit: IPCC AR5 executive summary

These factors (temperature, CO₂ levels and water availability) interact to complicate matters further. High carbon dioxide levels may mean plants need fewer stomata, which would reduce the amount of water they lose to the air. On the other hand, higher temperatures and/or increased rainfall may mean that crop diseases spread more quickly and reduce yields.

Overall Lobell and Gourdji state that climate change is unlikely to result in a net decline in global crop yields, although there will likely be regional losses that devastate local communities. They argue that climate change may prevent the increases in crop yields required to support the growing global population however.

The effect of climate change on global crop yields is extremely complex and difficult to predict, however floods, drought and extreme temperatures will mean that its impact on global food security (“when all people at all times have access to sufficient, safe, nutritious food to maintain a healthy and active life”) will almost certainly be devastating.

On the basis of the IPCC report and the predicted impact of climate change on all aspects of our planet, not just food security, it is critical that we act quickly to prevent temperature and CO₂ levels rising any further.

This blog is written by Sarah Jose, Biological Sciences, University of Bristol

You can follow Sarah on Twitter @JoseSci

Sarah Jose

Tales from the field: reconstructing past warm climates

Posted on August 11, 2013April 19, 2023 by janet.crompton

The warmest period of the past 65 million years was the early Eocene epoch (55 to 48 million years ago). During this period, the equator-to-pole temperature gradient was reduced and atmospheric carbon dioxide (pCO2) was in excess of 1000ppm. The early Eocene has received considerable interest because it may provide insight into the response of Earth’s climate and biosphere to the high atmospheric carbon dioxide levels that are expected in the near future as a consequence of unabated anthropogenic carbon emissions (IPCC AR4). However, climatic conditions of the early Eocene ‘greenhouse world’, are poorly constrained, particularly in mid-to-low latitude terrestrial environments (Huber and Caballero, 2011).

I recently spent a week in eastern Germany (Schoeningen, Lower Saxony) sampling an early Eocene lignite seam (Fig. 1). Lignite is a type of soft brown coal that is an excellent terrestrial climate archive. Using palynology, organic geochemistry, coal petrography and climate models, we will try to reconstruct the terrestrial environment of the early Eocene and provide insights into future climate change.

Fig. 1. A view of the mine with Dr. Volker Wilde on the far right for scale.

During this trip, we were sampling at the base of the mine beside a very large and very dusty bucket-wheel excavator (Fig. 2). A bucket-wheel excavator is a continuous digging machine over 200m long and dwarfs the large NASA Crawler that transports space shuttles to launch pads. Once the lignite is removed, it is placed upon a conveyor belt and transported immediately to a nearby power station. Unfortunately, the Schoeningen lignite will not last forever and the town will have to consider other energy sources (e.g. wind).

Fig. 2. A bucket-wheel excavator at Schoeningen mine.

Our sampling technique was less impressive yet equally effective. All we required were hammers, chisels and pick-axes (Fig. 3.). After a long day of sampling, we were taken to a very special outcrop at the top of the mine. The exposure contained well-reserved palm tree stumps from the early Eocene and provide evidence for white beaches, tropical plants and endless sunshine on the German coastline. An ideal holiday destination!

Fig. 3. Dr. Marcus Badger sampling Main Seam in high resolution.

Following fieldwork we were taken to the new Schoeningen museum containing, amongst other artefacts, the Schoeningen Spears (Fig. 4). The Schoeningen spears are 300,000 years old and are the oldest human weapons in existence. The spears were found with approximately 16,000 animal bones, amongst them 90% were horse bones, followed by red deer and bison. It has been proposed that these spears were the earliest projectile weapons and were used for ‘big game hunts’. Although this theory has been questioned, it remains one of the worlds most exciting archaeological finds.

Fig.4. The Schoeningen spears. Most were preserved fully intact.

Now we are back in Bristol its time to start processing our samples so we can understand what the early Eocene terrestrial climate was like. Watch this space!

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The trip was in collaboration with members of Bristol (UK), Royal Holloway (UK), Gottingen (Germany) and Senckenberg (Germay).This blog was written by Gordon Inglis (http://climategordon.wordpress.com).