March 2014 – Cabot Institute for the Environment blog

2nd Generation biofuels: a transdisciplinary dialogue

Posted on March 24, 2014April 19, 2023 by janet.crompton

“Globally, there are politically important evidence gaps, but nationally, those evidence gaps are just not important enough for policy-makers to take account of them”.

This was one comment summing up the discussion I had at a workshop on the development of 2nd generation, or cellulosic, biofuels (biofuels produced from crops or waste, that is not otherwise used as food). The workshop’s aim was to produce ‘A transdisciplinary dialogue on the opportunities and challenges of cellulosic ethanol in the UK’, and was run by Dr. Kate Millar, the Director of the Centre for Applied Bioethics. It was part of a number of events convened for the EU Framework 7 project, “Integrated EST-Framework” (EST-Frame). Bringing together 12 scientists, engineers, environmental scientists and social scientists is not an easy feat, but the 24 hours’ of the workshop produced some extremely interesting discussions.

My own research considers endeavours to overcome some of the sustainability problems commonly associated with 1st generation biofuels (e.g. sugarcane and wheat), and so I was particularly interested in how the development of 2nd generation biofuels might change the sustainability landscape. Would many of the problems associated with biofuels in general – increased greenhouse gas (GHG) emissions when compared with fossil fuels, land grabbing, food insecurity and biodiversity loss – disappear if we were to start producing 2nd generation biofuels?

Policy problems

Oilseed rape grown for 1st
generation biofuel has limitations.
Image credit: Richard Webb

Much of the first day of the workshop was spent discussing ‘policy problems’ that would need to be overcome for the successful production of cellulosic biofuel for consumption in the UK. 2nd generation biofuels have not been viably commercialised to date largely because of the cost of production. But this is not the only policy problem to be overcome. 2nd generation biofuel will not only come from ‘waste’, but also from crops, such as miscanthus, which are specifically grown as biofuel feedstock. But policies to encourage the use of crop residues for biofuels, depend, first, upon the categorisation of the cellulose left behind in the farming of particular crops as ‘waste’ and, second, upon a decision that the ‘best’ use of that waste is its conversion to energy. This decision may, in turn, depend upon an assumption relating to national energy security.

When discussing the problems that would need to be overcome for the production of 2nd generation biofuel, it soon became clear that our own understanding of the problems depended upon the frames through which they were envisioned, and/or the assumptions that might be made in even categorising them as problems in the first place. Such frames and assumptions need to be unpicked when making policy decisions relating to, for example, the ‘best’ use of land, the ‘best’ conversion processes, displacement effects resulting from the adoption of those policies, and the valuations made in assessing ‘costs’ resulting from the production of such biofuels.

Indirect land use change (ILUC)

One thorny issue relating to biofuels production has been that of ILUC. ILUC has been a huge spoke in the wheel of policy-makers’ development of policy in relation to the development of biofuels, not only in the UK, but in the EU, and further afield. Endeavouring to tackle this issue involves identifying potential knock-on effects resulting from direct land use change to biofuels feedstocks (whether 1st or 2nd generation). These might include increased GHG emissions, erosion, biodiversity loss, or increased insecurity in relation to land rights or food supply of local people.

While the focus of policy-makers’ concerns in relation to ILUC has to date been GHG emissions, views in relation to all of these issues also depend upon one’s assumptions/framing. Furthermore, such issues are by their very definition uncertain (because they involve future potential scenarios) and, in tackling each of them, require policy-makers to give value (either positive or negative value) to those potential scenarios. Some of the values endowed by policy-makers in assessing indirect or direct land use change may be quantifiable. Others, such as the values given by local people to their landscape before it is transformed for biofuel feedstocks, may not be. Moreover, land use change resulting from policies made in the UK, may be taking place in countries as far afield as Africa or South East Asia, for example.

While some participants thought that this demonstrated that even endeavouring to tackle an issue such as ILUC was purely altruistic, and therefore usually not important enough for national policy-makers to be swayed by, others argued that it was not altruism that demanded its recognition, but an appreciation of the integrated nature of our world, its people and environment, and markets for feedstocks. Without actively sympathising with policy-makers, many participants recognised that there are no right answers when it comes to ILUC.

Need for a holistic approach in policy-making

Image by Steve Jurvetson

When discussion moved on to consider the types of evidence required for policy-makers to tackle the policy problems, we soon realised that different forms of ‘evidence’ were often integrated. Moreover, it was not lack of evidence that was the problem for policy-makers, or even ambiguity and uncertainty in the evidence, but the appraisal of that evidence. This requires political decisions to be taken, something that policy-makers seem, ironically, to be distinctly uncomfortable with in relation to this area.

The workshop was a valuable exercise. To paraphrase one participant: many of the technical or economic issues relating to the development of cellulosic biofuels in the UK could be resolved by taking a very narrow view of the problem. However, such issues do encompass wider issues. Countering the scientists’ and engineers’ ‘problem-solving’ approaches to policy issues, with social scientists’ more critical understanding of the social issues surrounding the problems is always going to be a challenge, but one that, I believe, is crucial if those problems are really going to be solved with any success.

This blog is written by Cabot Institute member Dr Elizabeth Fortin, University of Bristol Law School.

Crisis in Ukraine: The energy implications

Posted on March 21, 2014April 19, 2023 by janet.crompton

Energy security- a primarily theoretical concept in recent years that has been made startlingly real by the recent developments in Ukraine. But what could the possible repercussions of this crisis be on European energy policies and our fuel bills?

I had a chance to ask this question during a recent event at the House of Commons, hosted by the APPCCG and Sandbag. The answer surprised me.

According to Baroness Worthington, director of Sandbag and member of the House of Lords, two outcomes are broadly possible.

Figure 1: Map of Ukraine

The first scenario is of a stabilisation of the diplomatic situation and the emergence of a westward-leaning Ukraine. In this situation, it is likely that Ukraine might choose to exploit its own natural gas reserves, estimated to be in the region of 1.1 trillion cubic metres. Ukraine possesses the 26^th largest natural gas reserve in the world, which is estimated to be more than half the size of the combined reserves of the EU.

If Ukraine `turns on the taps’, this would solve their immediate energy dependence on Russia and produce a revenue stream to support their economy. However, exploiting natural resources on the scale required would require significant investment, and Ukrainians would have to accept the change in land use and economic transformations that come with becoming a major energy exporter.

This optimistic outcome seems open to several criticisms. It’s unclear at this moment where investment would come from, and whether Russia would oppose competition in the European energy market. Moreover, can Ukraine ever completely replace Russia as an energy supplier? For instance, Russia’s natural gas reserves are around 40 times the size of Ukraine’s.

The second scenario is of a destabilised Ukraine, whose policies are influenced to a significant degree by Moscow. In this situation, European nations would need to purchase natural gas in the short-to-medium term from Russia and Ukraine, and tamely accept price rises and the uncertainty and energy insecurity that comes with dependence on a foreign nation for energy supplies.

This second possibility may also be criticised; Russia may not have further demands after the annexation of Crimea is completed. It may be the case that Russia wish to return to business as usual as quickly as possible, and may choose to offer energy supplies on favourable terms to Europe in order to encourage the resumption of trade and renewed trust.

In my view, both scenarios will result in one predominant outcome: the loss of trust. It seems unlikely that Russia can regain the trust of the West quickly; by it’s very nature, trust takes years to accrue and moments to lose. Energy security will become a much larger talking point in the next few years if relations with Russia continue to remain cool. Nations that previously were willing to base their energy supply on foreign gas purchases will choose instead to pay a price or environmental premium to source those supplies from more trusted sources.

The nations most likely to make changes to their energy mix as a result of this crisis are Germany and Poland. Germany’s choice to abandon nuclear fission after the Fukushima crisis leaves them slightly more vulnerable to a loss of fuel supplies from abroad, and they may choose to shift further towards renewables, or attempt the politically difficult U-turn of returning to nuclear power. Poland uses natural gas and coal to power much of its economy, a significant portion of which is purchased from Russia. Since the fall of the Soviet Union, Poland has been consistently suspicious of Russia, and may decide that now is the time to reduce or remove their dependence on Russian supplies.

Figure 2: DECC figure for natural gas supplies by source, 2010-2013

As for the fuel bills of UK consumers, it’s unlikely that we will see any immediate effects. If sanctions on Russia are imposed, this may raise gas prices worldwide, but the UK does not directly obtain its supplies from Russia. The most likely change to the UK’s energy mix will be one that was on the cards already- an expansion in the exploitation of shale gas. Using energy security as a primary argument, supporters of shale gas may now find it easier to convince others that fracking and onshore gas exploitation should continue or be accelerated.

Perhaps the Ukraine crisis will be the public relations coup the shale gas industry has been looking for.

This blog is written by Neeraj Oak, Cabot Institute.

Neeraj Oak

Setting-up new collaborations with geoscientists from Kazakhstan

Posted on March 20, 2014April 19, 2023 by janet.crompton

A map of Kazakstan
(from GraphicMaps.com, World Atlas)

Landlocked in central Asia, Kazakhstan is the world 9th largest country, larger than Western Europe. It is host to one of largest amounts of accessible minerals and fossil fuel. Even though, Kazakhstan is relatively unknown to the general public and geoscientists. In order to encourage international research collaboration between ambitious young researchers from the UK and Kazakhstan, in March 2014 the British Council Researcher Links organized a workshop in Ust-Kamenogorsk in Kazakhstan.

I was selected to attend this meeting and as a result I found myself on a Monday afternoon boarding a plane to Kazakhstan together with 12 other UK scientists. My main reason to attend the workshop was that palaeoclimatic reconstructions from this part of the world are almost non-existant. This while in the geological past (Mesozoic and Paleogene) Kazakhstan was on the bottom of a large epicontinental ocean that connected the Tethys Ocean with the Arctic. Any palaeoclimatic records from this region of the world are thus very valuable and could provide key-insights into deep-time paleoclimate. I hoped that some scientists worked on palaeoclimate reconstructions. Publications were sparse, and sometimes in Russian, so hopefully a face-to-face meeting would be good start for collaboration.

The modern campus of the East Kazakhstan
State Technical University in Ust-Kamenogorsk.

The first personal encounter with the vast size of Kazakhstan and remoteness was the time in took us to get there. Flying from London, it took us more than 24 hours to get to the small city of Ust-Kamenogorsk, located in northeastern Kazakhstan. Although temperatures in the UK reached a comfortable 18 degrees C that day, in Ust-Kamenogorsk day temperatures were well below freezing and winter still in full swing. Snow was packed half a meter high at the side of the roads.

The workshop was held at the modern campus of the East Kazakhstan State Technical University. The first days were filled with presentations from both UK and Kazakh scientists, as well as Simon Williams, the Director of the British Council Kazakhstan. An interpreter was used to translate Russian into English and vice versa. It was very interesting to give a presentation with an interpreter, it makes you very conscious of what you say and forces you to talk in brief and concise sentences. I was very happy to hear that several Kazakh palaeoclimatologist were present and very enthusiastic to share their results and ideas. Although palaeoclimate is not a top research priority in Kazakhstan, it was impressive to see the work that was already done. Several scientists worked on sections covering all periods from the Cambrian to the early Cenozoic and detailed stratigraphies were developed. We saw dinosaur eggs, beautifully preserved fossil leaves, fossil fish, and remains of large ferns. Very exciting! We had an impressive lab tour in which they showed us an array of state-of-the-art instruments that would make some UK-geoscientists jealous.

All geared-up and ready to descend into the mine.

(I am on the right!)

As a main theme of the workshop was mining, the 3^rd day we visited the Maleevka Mine near Zyryanovsk. After a detailed explanation of the daily operations of the mine, which mainly produces copper and zinc, we went down into the mine and had an amazing and slick two-hour tour. Although I am not an expert in mining, it was fascinating to see the mining operations from close-by. I was impressed by the state-of-the-art technology and know-how and safety regulations.

Remote-controlled mine dozer used to safely
get ore from newly blasted areas.

After four intense days (and nights), it was time to make the 30hr journey back to Bristol. My overall impression is that Kazakhstan is an amazingly beautiful country. It was impressive to fly for hours over snow-covered steppe and mountains. Although the weather was cold, the people were incredible warm and friendly. Wherever we went, people welcomed us with smiles and food, lots and lots of great food! The workshop was incredibly well organized. I definitely want to come back to this country. In fact, the last day one scientist gave me some Paleocene samples that I literally had to smuggle out of the country and which we will use for a pilot study. In the near future we aim to organize another workshop in Kazakhstan, focusing especially on palaeoclimate and hopefully some fieldwork because there is so much potential for great science and collaboration!

The British Council organized this trip. The UK coordinator was Prof. K. Jeffrey from the Camborne School of Mines, University of Exeter.

This blog is written by Dr David Naafs who is a Postdoctoral Research Fellow in the Organic Geochemistry Research Unit at the Cabot Institute, University of Bristol.

The controversy of the Greenland ice sheet

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

I was expecting a dusty road, a saloon door swinging, two geologists standing facing each other in spurrs and cowboy hats with their hands twitching at their sides, both ready to whip out their data and take down their opponent with one well-argued conclusion.

Sadly (for me), things were much more friendly at Professor Pete Nienow‘s seminar in Bristol’s Geographical Sciences department last week. Twelve years ago he visited the University with a controversial hypothesis, causing considerable debate with members of the department. Now he was back, Powerpoint at the ready, to revisit the theory.

Professor Nienow is a glaciologist at the University of Edinburgh. He is currently researching glacial movement and mass in Greenland, but I’ll let him tell you more.

Pete Nienow – GeoScience from Research in a Nutshell on Vimeo.

The Greenland ice sheet covers almost 80% of the country, enclosed by mountains around its edges. The ice sheet is dynamic; glaciers are constantly moving down from the summit towards the sea but replaced each winter by snow. Glaciers are funnelled through the mountains in large “outlet glaciers” that either melt or break into icebergs when they reach the sea.

There is plenty of evidence to suggest that the outlet glaciers are speeding up, rushing down to meet the sea almost twice as fast as they did in the 1970s. Unfortunately that means more melting icebergs floating around, contributing to sea level rise. The winter snowfall is not able to replenish this increased loss of glacial mass, so the Greenland ice sheet is slowly shrinking.

Coverage of the Greenland ice sheet in different future climate change scenarios. A critical tipping
point could be reached, after which it will be impossible to stop the ice from melting and raising sea
levels by seven metres globally. Source: Alley et al., 2005 (Science)

Controversy

Professor Nienow stirred up a debate in 2002, when he proposed that the Zwally Effect could be hugely important for the Greenland ice sheet. This theory suggests that meltwater could seep down through the glacier to the bedrock, lubricating and speeding up the glacial movement.

The conventional wisdom of the time was that it would be impossible for meltwater to pass through the 2km of solid ice that comprises most of the Greenland ice sheet. The centre of the glacier is around -15 to -20°C, so the just-above-freezing water would never be able to melt its way through.

Meltwater research

Meltwater on glaciers often pools on the surface, creating supraglacial lakes. These lakes can drain slowly over the surface, but Professor Nienow found that they can disappear rapidly too. The water slips down through cracks in the ice to the bedrock, leading to a rapid spike in the amount of meltwater leaving the glacier.

Supraglacial lake.
Source: United States Geological Survey, Wikimedia Commons

Meltwater can reach the base of the glacier so that’s one point to Nienow, but can this actually affect the movement of the glacier?

During the summer, the higher temperatures lead to increased glacial melting, which drains down to the bedrock. This raises the water pressure under the glacier, forcing it to slide more rapidly. Interestingly, as the season progresses, Nienow found that the meltwater forms more efficient drainage channels beneath the glacier, stabilising the speed of the ice.

Nienow was almost ready to mosey on back to Bristol, show them how subglacial meltwater had clear implications of glacier loss for a warmer world, and declare himself the Last Geologist Standing.

Turning point

Glaciologists had always assumed that the winter glacier velocity was consistently low. However, at the end of a very warm 2010, Nienow and his colleagues discovered a blip of especially low speeds, even slower than the standard winter “constant”.

The large channels underneath the glaciers formed by the extra meltwater of that hot year actually reduced the subglacial water pressure during the winter, slowing the glacier more than on a normal year. Nienow found that this winter variability is critical for overall glacier velocity and displacement. In 2010, the net effect of both summer and winter actually meant that the glacier velocity was reduced in this hot year.

Back to Bristol

Nienow returned to Bristol to give his seminar. Somewhat unlike a cowboy film, Nienow concluded that it was a draw; he’d been right that it was possible for meltwater to seep down to the bedrock and lubricate glacial movement, but his friends at Bristol had been correct in thinking that it wasn’t very important in the grand scheme of things.

A collaborative paper between Professor Nienow, the Bristol team and other glaciologists from around the world found that subglacial meltwater will only have a minor impact on sea level rise, contributing less than 1cm of water globally by 2200. Surface run off and the production of icebergs will continue to play a bigger role, even in a warming world. The computer models used to predict sea level rise will be able to include these findings to give a more accurate insight into future glacier movement and coverage across Greenland and beyond.

Bristol glaciologist Dr. Sarah Shannon, lead author on the paper, pointed out that whilst overall glacier velocity is unlikely to be affected by subglacial meltwater in warm years, “global warming will still contribute to sea level rise by increasing surface melting which will run directly into the ocean”.

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

You can follow Sarah on Twitter @JoseSci

Sarah Jose

Do not make policy during the middle of a flood crisis

Posted on March 14, 2014April 19, 2023 by janet.crompton

Across the country, we have seen our neighbours’ homes and farms devastated by the floods. We understand their anger and frustration. We understand their demands for swift action.

What they have been given is political gamesmanship. Blame shifting from party to party, minister to minister, late responses, dramatic reversals of opinion. It reached its well-publicised nadir this past weekend, with Eric Pickles’ appearance on the Andrew Marr show:

‘I apologise unreservedly and I’m really sorry that we took the advice; we thought we were dealing with experts.’

Throwing your own government experts to the wolves is not an apology.

This political vitriol, at least with respect to the Somerset Levels, all appears to come down to a relatively simple question – should we have been dredging?

This is not a simple question.

It is an incredibly complex question, in the Somerset Levels and elsewhere, and this simplistic discussion does the people of those communities a great disservice.

Image by Juni

But more fundamentally, this is not the time to be deciding long-term flood mitigation strategy. In times of disaster, you do disaster management. Later, you learn the lessons from that disaster. And finally, informed by evidence and motivated by what has happened, you set policy. And that, to me, is the most frustrating aspect of the current political debate. In an effort to out-manoeuvre one another, our leaders are making promises to enact policy for which the benefits appear dubious.

So, what are some of the issues, both for Somerset and in general?

First, the reason the rivers are flooding is primarily the exceptional rainfall – January was the wettest winter month in almost 250 years. This rain occurred after a fairly damp period, so that the soil moisture content was already high. However, these issues are exacerbated by how we have changed our floodplains, with both agricultural and urban development reducing water storage capacity.

Second, as the 2013-2014 flooding crisis has illustrated, much of our nation is flood-prone; however, those floods come in a variety of forms and have a range of exacerbating causes – some have been due to coastal storm surges, some due to flash floods caused by rapid flow from poorly managed lands and some due to sustained rain and soil saturation. We have a wet and volatile climate, 11,073 miles of coastline and little geographical room to manoeuvre on our small island. Our solutions have to consider all of these issues, and they must recognise that any change in a river catchment will affect our neighbours downstream.

Flooding on West Moor, Somerset Levels
Image by Nigel Mykura

Third, returning to the specific challenge of the Somerset Levels, it is unclear what benefit dredging will have. The Somerset Levels sit near sea level, such that the river to sea gradient is very shallow. Thus, rivers will only drain during low tide even if they are dredged. And widening the channels will actually allow more of the tide to enter. Some have argued that in the past, dredging was more common and flooding apparently less so. However, this winter has seen far more rain and our land is being used in very different ways: the memories of three decades ago are not entirely relevant.

Fourth, where dredging is done, it is being made more costly and challenging by land use practices elsewhere in the catchment. The rivers are filling with sediment that has eroded from intensively farmed land in the headwaters of the catchments and from the levels themselves. Practices that have greatly accelerated erosion include: heavy machinery operations in wet fields; placement of gates at the bottom of hillslopes so that sediment eroded from the field is very efficiently transported to impermeable road surfaces, and thence to streams downslope; cultivation of arable crops on overly steep slopes (increasing the efficiency of sediment transport from land to stream); overwintering of livestock on steep slopes; and excessive stocking densities on land vulnerable to erosion.

Image by Nicholas Howden

Nutrient enrichment from livestock waste and artificial fertilisers (when used in excess of crop requirements) also contribute to the dredging problem. The nutrient loading often exceeds the system’s recycling capacity, such that nutrients flow into ditches and waterways, stimulating growth of aquatic plants that can readily clog up the minor ditches and waterways. With less space to dissipate water within the network, it is forced into the main channel. In other words, some of these floods are a subsidised cost of agriculture – and by extension the low costs we demand of our UK-produced food.

And finally, if we are going to consider long-term planning, we must consider climate change impacts. Flooding will become worse due to sea level rise, which has already risen by about 12cm in the last 100 years, with a further 11-16cm of sea level rise projected by 2030. It is less clear how climate change will affect the intensity and frequency of these particularly intense rainfall events. Although almost all projections indicate that dry areas will become dryer and wet areas will become wetter, predictions for specific geographical regions are highly uncertain. And our historical records are not long enough to unravel long-term trends in the frequency of uncommon but high impact weather events. This should not be reassuring – it is another major element of uncertainty in an already complex problem.

As challenging as these issues are, they are not intractable. The solutions will involve stronger planning control and scientifically informed planning decisions (including allowing some areas to flood), a reconsideration of some intensive farming practices, some dredging in key areas, some controlled flooding in others, and better disaster management strategy for when the inevitable flooding does occur. But now is not the time to resolve such a complicated knot of complex issues. It is certainly not the time to offer false promises or miracle cures.

Now is the time to help our neighbours in distress, listen to their stories, and remember them when the floodwaters recede. And then we should let our experts get on with their jobs.
—
This blog is co-written by Professor Paul Bates, Professor Penny Johnes (Geographical Sciences), Professor Rich Pancost (Chemistry) and Professor Thorsten Wagener (Engineering), all of whom are senior members of the Cabot Institute at the University of Bristol.

This blog post was first published in the Guardian on 12/02/2014, titled Flood crisis: Dredging is a simplistic response to a complex problem.

If you have any media queries relating to this blog, please contact Paul Bates or Rich Pancost (contact details in links above).

Prof Paul Bates, Head of
Geographical Sciences

Prof Rich Pancost, Director of the
Cabot Institute

‘New’ man-made gases: Ozone crisis or hoax?

Posted on March 14, 2014April 19, 2023 by janet.crompton

Image by PiccoloNamek (English wikipedia)
[GFDL (www.gnu.org/copyleft/fdl.html),
via Wikimedia Commons

You may have noticed a story reported on widely recently on the discovery of 4 ‘new’ man-made ozone-depleting gases. This follows the publication of a study in the journal Nature Geoscience on the first measurements of these gases, their abundances in the atmosphere and estimated global emission rates. Responses to the reporting of this publication have ranged from the Daily Mail’s “Ozone Crisis” to the inevitable internet-based diatribe of “any research from UEA is clearly made up” in various comment sections. So just how concerned should we be about the emissions of these four gases?

Chlorofluorcarbons (CFCs)

The reason we care about CFCs is because they deplete ozone high up in the atmosphere, potentially exposing humans to harmful UV rays. Oh, they also happen to be extremely potent greenhouse gases, with each molecule of a CFC being equivalent to 1000s of molecules of CO₂, and they sit around in the atmosphere for 10s or 100s of years before being removed. Basically they’re pretty bad, and sure they might have been great refrigerants and aerosol propellants but at what cost?

The production of CFCs has now to all intents and purposes ceased, although that doesn’t mean that emissions have completely stopped; various banks of these gases exist in fridges for example. These might leak during use or when destroyed. So it’s not entirely surprising to read that this study has found that various CFCs are still being released.

Newly measured

In fact the reason this paper is important is more to do with the fact that these gases have never before been measured. Many of the media articles seem to lead with the fact these are ‘new’ ozone-depleting gases, which is a little misleading. They’re not new; they’ve been around for decades, only nobody has been able to measure them in the atmosphere before. Why’s that you might ask? Well much of it is to do with just how small their concentrations are in the atmosphere.

The fact of the matter is that the concentrations of these gases (CFC-112, CFC-112a, CFC-113a, HCFC-133a) are tiny. All four have atmospheric mixing ratios of less than 1 part per trillion (ppt). In other words, if you could isolate a trillion molecules of air (1 x 10¹²) then not even one of them would be one of these ’new’ CFCs. By contrast CO₂ in the atmosphere has a mixing ratio of hundreds of parts per million.

Compare these newly measured gases to the major CFCs (CFC-11, CFC-12, CFC-113) whose current atmospheric concentrations are hundreds if not thousands of times greater. Even though emissions of these major CFCs are now close to zero they will still be around in the atmosphere at these elevated concentrations for decades to come. This is shown in the plot below taken from the AGAGE network measurements of CFC-12. Although the concentration has reached a peak it will take at least one hundred years for levels to get back down to pre-1980 levels, with the current mixing ratio still over 500 ppt.

Plot taken from the AGAGE network measurements of CFC-12

So emissions of these newly measured gases would have to really pick up for a sustained period of time to add significantly to the ozone-depleting effect of what is already in the atmosphere. To say the measurement of these compounds has created some sort of ozone crisis is therefore a gross exaggeration. That’s not to say that this work was a waste of time; it’s vital that we know about these compounds and their atmospheric abundance so we can ensure their contribution to ozone depletion remains negligible.

Other factors influencing ozone recovery

There are other potentially more important causes for concern as well. Hydrochlorofluorocarbons (HCFCs) were introduced as replacements for CFCs but also contribute to ozone depletion, albeit in a less effective way. Although these are also being phased out many of these will have a greater impact on the recovery of the ozone ‘hole’ than these newly measured species. Just a few months ago the United Nations Environment Programme (UNEP) released a report saying another gas, Nitrous Oxide (N₂O), is now considered to be the biggest threat to the ozone layer over the next 50 years. Not to mention that one of the impacts of a rise in global surface temperatures could be a slowing in ozone hole recovery. There’s a genuinely interesting (honest!) explanation for why that is which I will cover in another blog.

The point is that there are lots of factors which affect the Earth’s ozone layer. Studies like the one recently published in Nature Geoscience are vital for our understanding of what the recent and current atmospheric composition is like. It might not be a problem now, but surely the key to looking after our planet, and ourselves, is to prevent things from becoming problematic in future. If we can take steps to find out where these emissions are coming from and why some of them are increasing then measures could be put in place to limit their future influence on ozone recovery.

This blog is written by Mark Lunt, Atmospheric Chemistry Reseach Group, Cabot Institute, University of Bristol, .

Mark Lunt