Green Great Britain Week – Cabot Institute for the Environment blog

Local students + local communities = action on the local environment

Posted on October 19, 2018April 13, 2023 by janet.crompton

As part of Green Great Britain Week, supported by BEIS, we are posting a series of blogs throughout the week highlighting what work is going on at the University of Bristol’s Cabot Institute for the Environment to help provide up to date climate science, technology and solutions for government and industry. We will also be highlighting some of the big sustainability actions happening across the University and local community in order to do our part to mitigate the negative effects of global warming. Today our blog will look at ‘Climate action in communities.

Geography students from the University of Bristol spent February 2018 working on air, soil and water quality research projects for local organisations and community groups, including Bristol Green Capital Partnership members. Below is a summary of each project, the findings and next steps.

Bristol City Council – Bristol Urban Heat Island effect

Students investigated the effects of urban and suburban heat islands within Bristol compared to local rural areas. Urban Heat Island can impact human health, air and water quality and energy demand in the City with implications for future planning and city resilience. This project aimed to provide early groundwork for Bristol City Council in developing a better understanding of the Urban Heat Island in the city. The group used fifteen Tinytags across the city to collect temperature data and gained secondary data from local weather stations and building management systems. The group used a contour graph (see image below) to illustrate the UHIs they found, there was significant differences (c.1.3C) between rural sites, such as Fenswood Farm, Long Ashton compared to urban sites in close proximity, such as Hotwells Road. Bristol City Council will be using this data and other insights generated through participation in the project to inform i) the co-development of an urban temperature monitoring network and ii) further research into the Urban Heat Island effect.

Malago Valley Conservation Group – water pollution in the River Malago

Students investigated how water quality varied along the River Malago in Bishopsworth and what biological impact the dam has on microplastics and pollution in the river. Initially the group collected GPS data to map the river course and used water quality samples from 40 sites along the river to record nutrient, chlorophyll and microplastic data. The team found that some microplastic build up was evident before dams and weirs along the river and nitrate concentrations increased downstream through nitrification which suggests there may be impacts on the ecology of the river. Overall the river was found to be relatively healthy according to DEFRA and Environment Agency data, but there were recommended actions to protect its health in the future. The Malago Valley Conservation Group will be using the findings to plan conversation work programmes with their volunteers.

Bristol Avon Rivers Trust – water pollution in Three Brooks Lake

Students investigated the Three Brooks Lake and accompanying urban brooks in North Bristol to see if there was a difference in pollution levels entering the lake from two brooks from separate local residential areas. The group collected twenty water samples from the site and secondary data from the Environment Agency to examine variations in the pH, nutrient concentrations, turbidity (cloudiness of the water) and microplastics levels at the site. The findings suggested that there is likely to be a difference in the water quality of the two brooks and that the lake may be a sink for water pollution in the area. The Three Brooks Nature Reserve group will use the findings to support the development of a local management plan and the Bristol Avon Rivers Trust will be using the findings to contribute to their existing knowledge base for the catchment and to search for funding to develop the research further and to undertake any necessary improvements.

Friends of Badock’s Wood – wildflower cultivation in Badock’s Wood

Students investigated the soil conditions in Badock’s Wood to support the cultivation of wildflower meadows. The group collected soil cores from three meadows and a control meadow to analyse the soil moisture and organic matter content in the lab. Most wildflower species prefer calcareous soils (>15% calcium) with low phosphorous and high nitrogen content to grow optimally. Findings showed that two meadows have calcareous soils and two were on the borderline, all meadows had low phosphorus and low nitrogen content. In the present conditions, although some wildflowers do grow, the soil isn’t optimal to sustain the growth of many species but measures could be taken to improve the soil and more robust wildflowers could be selected to cope with soil conditions. The Friends of Badock’s Wood will be using the findings to revise their management plan for the site.

Dundry and Hartcliffe Wildlife Conservation Group – water pollution in Pigeonhouse stream tributaries

Students investigated water quality variances in five tributaries of the Pigeonhouse stream in Hartcliffe and whether this is influenced by land use in the area. The group collected samples to analyse the pH, nutrient content and temperature of the streams. The findings showed that the tributaries were healthy and unlikely to be contributing to water pollution levels in the Pigeonhouse stream and further downstream in the River Malago. The group suggested that high levels of nitrate in one tributary and Pigeonhouse stream were likely to be a result of run-off from neighbouring fertilised agricultural fields. E. Coli was prolific in all areas, the source of this will be a subject for future students to investigate. Dundry and Hartcliffe Wildlife Conservation Group will present the findings to the local neighbourhood partnership group.

Dundry and Hartcliffe Wildlife Conservation Group – effects of urban development and refuse on the Pigeonhouse Stream

Students investigated water quality along the Pigeonhouse stream in Hartcliffe. The group collected water samples to analyse for pH, nutrient content, turbidity and microplastic levels in the stream. Findings showed that microplastic pollution increased and turbidity (water cloudiness) decreased downstream as urbanisation increased. Ammonia and nitrogen concentrations were found to be high in the stream, but average compared to other streams in the region and within DEFRA safety standards. In-flow pipes from the surrounding urban areas are likely to be influencing the water quality in the stream. Dundry and Hartcliffe Wildlife Conservation Group will use the report to work with Bristol Waste to reduce fly-tipping in the area and with the local neighbourhood partnership to develop strategies to reduce pollution from the in-flow pipes.

Friends of Bristol Harbourside Reed Bed – impacts of reed beds on water quality in Bristol Floating Harbour

Students investigated spatial variation in water quality across the reed bed. The group collected twenty-one water samples and analysed for E.Coli, heavy metals, pH and nutrient content. Findings showed usual levels of heavy metals, except for zinc which was ten times higher than expected. There was no evidence that the reed bed influenced nutrient concentrations or pH levels, but this may be different if the research was conducted in summer during peak growing season. High levels of chlorophyll were found over the reed bed which can result in algae blooms. The group recommended that the reed beds should be cut back annually in autumn, this will reduce the amount of dead plant matter in the water to maintain healthy levels of zinc and chlorophyll in the reed bed. Friends of Bristol Harbourside Reed Bed will be using the findings to inform their management plan of the reed bed.

Friends of Bristol Harbourside Reed Bed – the health of the Bristol Floating Harbour reed bed

Students investigated concentrations of heavy metals and microplastics in the reed bed which would impact the reed bed ecology. The group collected ten sediment samples and five reed samples to test in the lab. Findings showed usual nitrate and phosphate levels, but zinc and potassium levels were higher than in comparable rivers which may be due to houseboats dumping excrement in the water. Microplastics were prolific in the sediment samples and identified as a major pollutant in the reed bed. The reed beds were filtering some pollutants in the water, particularly potassium, but these will re-enter the ecological system if the reeds are left to die back. The group recommended that reeds were cut back annually to reduce pollutants in the water. Friends of Bristol Harbourside Reed Bed will be using the findings to inform their management plan of the reed bed.

Bristol Zoo – air pollution at Bristol Zoo

Students investigated CO2 levels as an indicator of air pollution levels at Bristol Zoo. The group collected data using CO2 probes and gas samples at five sites at Bristol Zoo and two control sites at Fenswood Farm, Long Ashton and Bear Pit Roundabout, City Centre. The analysis accounted for environmental factors such as temperature and windspeed. Findings showed that air pollution was higher at the boundaries of Bristol Zoo than in the centre, but not as high as in the city centre. The group suggested further investigations into the impact of the high boundary wall and roadside vegetation on air pollution at Bristol Zoo would be useful. Bristol Zoo will be using the findings to as a baseline for more research into air pollution at the site.

Narroways Millennium Green Trust

Students investigated the impacts of firepits on soil pollution and compaction at the Narroways Hill conservation site in St Werburghs. The group collected twenty soil samples to test in the lab. Findings showed that soil compaction was high in some areas of the site, but no evidence linked this to firepits at the site. Soil moisture was found to increase further from the firepits. There was not significant evidence to show heavy metal pollutants at the sites, except for arsenic which the group are investigating further. Narroways Millennium Green Trust will be using the findings to inform public communications around fires at the site.

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This blog is written by Amy Walsh from Skills Bridge. If your organisation would benefit from similar research, please email amy@bristolgreencapital.org.

Read other blogs in this Green Great Britain Week series:
1. Just the tip of the iceberg: Climate research at the Bristol Glaciology Centre
2. Monitoring greenhouse gas emissions: Now more important than ever?
3. Digital future of renewable energy
4. The new carbon economy – transforming waste into a resource
5. Systems thinking: 5 ways to be a more sustainable university
6. Local students + local communities = action on the local environment

Digital future of renewable energy

Posted on October 16, 2018April 13, 2023 by janet.crompton

1. Background

Today over 94% of the energy market in the UK is dominated by the Major Power Producers (MPP) who generate electricity and feed it to households and businesses over the grid [1].

Historically, to cut down on the fuel transportation costs, the major generation plants had to be located close to the fuel sources, i.e., where coal and oil were mined. The generated electricity would then be transmitted through power lines and distribution stations down to the households and businesses who would use the electricity up.

This structure of the industry was based on several constraints:

Electricity generation locations are constrained by the location of fossil sources (as it is cheaper and easier to transmit the generated electricity than to move fuel around);
Electricity generation requires large investments into large plants (due to economies of scale of the generation technology);
Electricity end users are only interested in consumption, and do not want to know much else about electricity itself.

Yet, technological advances as well as the societal understanding of the implications of the fossil fuel use have dramatically changed the framework within which the energy system operates:

Renewable generation technologies (such as solar panels, wind turbines, small hydro turbines) are now widely available for individual household and small community use.
As (most) renewable generation resources (e.g., solar or wind) are available where consumers are, it is technologically possible and economically affordable to generate and consume electricity locally, without centralised generation and transmission;
End users are increasingly interested in the environmental and social impact of the generated electricity, not only in consumption.

All the above, combined with the governmental subsidies for renewables installations (e.g., feed-in-tariffs) have led to a recent growth of micro-generation in the UK (i.e., individuals or organisations with small-scale energy generation, such as domestic wind or solar PV units). Such micro-generators consume their own generated energy and sell any excess back to the grid. Such generation offers the potential for a distributed model of energy generation and consumption that is not reliant on MPPs.

Challenge

Though presently, there is a successful renewables-based ecosystem in the UK, it has been largely driven by governmental subsidies. However, these subsides are now set to be withdrawn. As of March 2019 no new installations will be eligible to feed-in-tariffs. Will this result in fall of the renewables sector, as already experienced by solar PV sector in Spain [2] when their solar PV subsidies were removed? Or can UK micro-generators find another way of ensuring viability of renewable installations?

Opportunities

Research at the University of Bristol suggests that a subsidy-free localised renewables-based energy sector is not only possible but is also the best solution to the energy security and affordability dilemma. Our proposed model for the new, modernised UK energy sector is based around localised, but globally interconnected peer-to-peer energy markets underpinned by digital technology. This is illustrated in Figure 1 below:

Figure 1: Peninsula peer-to-peer energy market (from [6])

2. Peer-to-Peer energy market underpinned by digital platform

In a peer-to-peer energy market any two individuals/households can directly buy from and sell to each other, without intermediating third parties. These households can be both prosumers (i.e., producing and consuming own renewables-based electricity, as well as selling the excess to others), on simply consumers (if they have not own generation). Yet, unlike most microgrids, this is not an islanded model – which would require complete internal balance of supply and demand – but rather a “peninsula”. Where the locality experiences shortage or excess generation, the demand/supply are imbalance is resolved through trade with the other localities or the grid at large. The key advantages here are in providing avenues for:

Additional income streams to households with microgeneration – where the feed in tariff is no longer pays for the extra generation, the peers who use the energy do. Moreover, the price of the locally generated/consumed energy is more competitive than that of the grid supply as it does not need to pay the same full transmission, distribution, and utilities services charges. (Though I must underline that, as each locality remains interconnected with the gird, the energy costs will still include grid connection and maintenance changes. This is because the intermittency of the renewables generation must be insured against, and grid provides such an insurance and balancing services.)
Increasing value proposition of microgeneration and energy storage – the microgenerators are not only getting return to their generation investment, but are also supporting local communities’ energy needs, contributing to the decarbonisation and energy security efforts.
Increased control over source of supply – consumers are now able to express their preferences on energy purchase: do they wish to buy solar or wind, from the closest geographically located producer or from the cheapest supplier; do producers wish to donate their excess generation to the local school or to their extended family members, or to sell it to the highest bidder? All these options become viable when peers directly buy and sell from each other.

Such an energy system, however, cannot exist without a reliable and trusted digital platform which will both remove the 3rd party intermediation, and advertise the sale and purchase orders between the trading parties, undertake the users’ preferences-based matching of these orders, ensure security of the transitions, transparency of the trades, and accountability of the transaction participants.

To operate in such market:

the consumers and prosumers would join the platform and publish their preferences (e.g., sell to the highest bidder, or buy solar energy only, etc.);
the participants will they use their smart meter data to periodically (e.g., for every 15 min or half an hour) publish their sale and purchase orders on a digital platform;
for each trading period (e.g., 15 min.) the platform will match best fitting sale and purchase orders, and settle transaction accounts.

Note, (as illustrated in Fig 2) while in the current intermediated market the utilities act as the contracting parties between the prosumers, consumers and the energy market (see Fig. 2.a), in this peer-to-peer market each prosumer/consumer is the immediate contracting party itself (see Fig. 2.b).

Figure 2: Energy Market Dis-intermediation (from [6])

To realise these demanding requirements, we advocate use of distributed ledger technology for the energy trading platform [3, 4, 7]. Distributed ledgers (which incorporate blockchain and block-free technologies) are decentralised, distributed databases in which all transactions are immutably recorded. In other words, these are databases which are not controlled by any single company or individual, but are run and maintained by their participating membership. Data in these ledgers is redundantly stored in many locations, and cryptographically secured. As a result, once recorded, the data in the ledger cannot be changed and falsified [1].

The details on how to engineer this platform in such a way that engenders trust and participation is a topic of the HoSEM research project [5] and will be detailed in another blog post. For now, let’s assume that this platform is in successful operation. What are the implication of it on the UK energy market?

3. Implications on energy market

Move to a peer-to-peer energy trading over a distributed ledger will lead to several major changes in the UK’s energy system, to name a few:

First and foremost, it changes the structure of the energy system itself – from centralised fossil-based generation to decentralised, distributed, local renewables–based generation and consumption set up;
The digital technology-based market disintermediation (see section 2) deprecates the role of a trusted 3rd party (utilities in this case), reducing both the cost of transactions (i.e., energy) to the end users and allowing for the best possible preferences match to each participant. Now the suppliers are switched every trading period (e.g., every 15 min.), without any effort or cost to the market participants.
This structure also radically changes the role of the energy user – from the passive consumer to an active prosumer. The end user now matters, as every unit of produced and consumed energy is different. It is different because it is produced in the users’ local area, or is originated from solar/wined/gas sources, or is bought from a friend… Then the price of each energy unit is also different and that difference is decided on basis of the participants preferences.

Clearly, many issues remain to be resolved before this shift to a digitally enabled peer to peer market becomes a reality. These include issues of regulation and licensing (presently households are not allowed to act as suppliers in the UK), grid safety (e.g., current frequency assurance), geographical and population density (e.g., rural areas have more renewable per-person than cities), fairness and pricing (more affluent individuals can afford more generation installations), to name a few. Yet, it is encouraging to see that technologically and economically this future can be here already today.

Footnote

[1] Theoretically it is possible, but practically it is improbable, as record falsification is designed to be prohibitively costly [3].

References

[1] Dep. of Energy and Climate Change Updated energy and emissions projections 2015 Tech. Rep., URL: https://www.gov.uk/government/publications/updated-energy-and-emissions-projections-2015

[2] The rise and fall of solar energy in Spain, URL: http://www.abacoadvisers.com/spain-explained/life-in-spain/news/rise-and-fall-solar-energy-in-spain

[3] R. Chitchyan, J. Murkin, Review of Blockchain Technology and its Expectations: Case of the Energy Sector, URL: https://arxiv.org/abs/1803.03567

[4] J. Murkin, R. Chitchyan, D. Ferguson, Goal-Based Automation of Peer-to-Peer Electricity Trading, URL: https://link.springer.com/chapter/10.1007/978-3-319-65687-8_13

[5] Household-Supplier Energy Market, URL: https://gtr.ukri.org/projects?ref=EP%2FP031838%2F1

[6] Used from J. Murkin, R. Chitchyan, D. Ferguson, Towards peer-to-peer electricity trading in the UK, Presented at All Energy 2018, URL: https://reedexpo.app.box.com/s/plwhcfaqp6pnhxc8mcjznh7jtkevg9h1/file/292636529562

[7] J.Murkin, Automation of peer-to-peer electricity trading, blog post at https://www.edfenergy.com/about/energy-innovation/innovation-blog/research-development-peer-to-peer-trading

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This blog is written by Cabot Institute member Ruzanna Chitchyan from the University of Bristol Faculty of Engineering and has been reposted from Refactoring Energy Systems blog.

Ruzanna Chitchyan

Monitoring greenhouse gas emissions: Now more important than ever?

Posted on October 15, 2018April 13, 2023 by janet.crompton

The IPCC report

On 8 October 2018 the Intergovernmental Panel on Climate Change (IPCC) [1] published their special report on Global Warming of 1.5 ˚C. As little as 24 hours after the report had been published, the results of the report were already receiving extensive global coverage in the media, with BBC News describing the report as the “final call”. The BBC News article also explicitly mentions that this is “the most extensive warning yet on the risks of rising global temperatures. Their dramatic report on keeping that rise under 1.5 ˚C states that the world is now completely off track, heading instead towards 3 ˚C. Staying below 1.5 ˚C will require ‘rapid, far-reaching and unprecedented changes in all aspects of society’ [2].”

Reading the report has quite honestly been somewhat overwhelming but also necessary to understand exactly what we are in for. And as much as I understand the difficulty one might face either with the technical terms of the report or even the volume of information, I would really encourage you to give it a read. This special report covers a wide range of subjects from oceans, ice and flooding to crops, health and economy. However, if you do find that the chapters themselves are too lengthy or difficult, there is an amazing interactive, and very easy way that will help you explore the impacts of a 1.5 ˚C, 2 ˚C and beyond on Carbon Brief’s website.

There are two distinct parts in the IPCC special report. The full technical report that consists of 5 chapters and a short summary for policy makers (SPM). The SPM clearly states that “Estimated anthropogenic global warming matches the level of observed warming to within ±20 %” which translates into ‘almost 100 % of the warming is the result of human activity’ [3] [4].

We know for a fact that human activity is warming the planet

One outcome of this “human activity” that we often discuss is the emission of greenhouse gases (GHGs). Through various types of activities, whether that is agriculture, deforestation or burning fossil fuels, GHGs are emitted to the atmosphere. Without going too much into the chemistry and physics, what these GHGs do is change the mixing ratios within the atmosphere, resulting in greater absorbance of infrared radiation. And it is this change in the composition of our atmosphere that we refer to as the manmade greenhouse gas effect which also leads to the warming described in the IPCC report. But far more than the warming effect itself, global warming has all sorts of impacts most of which you can explore through the interactive link above.

Greenhouse gases and a long history of monitoring

Some of the ‘usual suspects’ in the discussion of GHG emissions are carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) (often described as the ‘major’ greenhouse gases [5]). However, an often-overlooked set of halogenated greenhouse gases are playing an increasingly large role in anthropogenic driven climate change. Gases like perfluorocarbons (PFCs) and hydrofluorocarbons (HFCs) are compounds that are emitted through some form of human activity. In the case of PFCs for example, the GHGs CF4 and C2F6 are two of the most volatile and long-lived gases monitored under the Kyoto protocol [6] and they are both primarily emitted through or during industrial processes. In contrast, HFCs are used widely as coolants in refrigerators and air-conditioning units, as blowing agents in foam manufacture and propellants in aerosols. They were originally introduced to replace ozone-depleting gases such as chlorofluorocarbons (CFCs), but like their predecessors, are potent greenhouse gases. Given the long lifetime of many of these halogenated gases, current emissions will influence the climate system for decades to come.

In order to monitor the accumulation of these gases in atmosphere, high-precision measurements are required. Through projects such as the Advanced Global Atmospheric Gases Experiment (AGAGE) [7] (figure 1 [8]) that has been measuring the composition of the global atmosphere continuously since 1978 and the National Oceanic and Atmospheric Administration’s Earth System Research Laboratory Global Monitoring Division, scientists have tracked the atmospheric concentrations of climate forcing gases from as far back as 1950s [9].

Figure 1: The AGAGE network

The Atmospheric Chemistry Research Group (ACRG) Chemistry Department, University of Bristol

The ACRG carries out research in the UK and worldwide in collaboration with other atmospheric chemistry research centres, universities and third parties. In the UK, the ACRG runs the UK Deriving Emissions linked to Climate Change network (DECC) [10], funded by the Department for Business, Energy and Industrial Strategy (BEIS) to measure atmospheric GHG and ozone depleting substances over the UK. These measurements are used in elaborate mathematical models to create top-down emission estimates for the UK and verify the UK GHG inventories submitted to the United Nations Framework Convention for Climate Change (UNFCCC) as part of the Kyoto protocol. Worldwide, the group is involved in the AGAGE network, monitoring global background levels of a wide range of GHGs. The ACRG runs 2 of the 9 global background stations under the AGAGE programme. One of these is the Mace Head station (Figure 2) on the west coast of Ireland, which is ideally placed for resolving northern hemispheric baseline air amongst European pollution events. The other AGAGE research station managed by the ACRG is the site at Ragged Point, Barbados. This site just north of the tropics, sits on the eastern edge of the island of Barbados and is directly exposed to the Atlantic. The researchers in ACRG study a variety of GHGs and a very large range of topics from maintaining instrument suites to ensuring the quality of the resulting data so that it can be used in modelling studies.

Figure 2: The Mace Head Station (Credit: Dr Kieran Stanley)

Why are measuring stations and networks like AGAGE so valuable and more important than ever?

The answer to this question is straightforward. Without measurement stations and their underlying networks, we would have very few means [11] by which to measure the accumulation of GHGs in the global atmosphere, and consequently no way of evaluating their emissions without relying on statistics from the industries that emit them. The current IPCC report is underpinned by such measurements, which allow scientists to estimate the impact of anthropogenic activity on past, present and future climates.

From Mauna Loa and its 60 -year record of atmospheric CO2 [12], to unexpected growth in emissions of banned substances such as CFC – 11 [13] and monitoring the accumulation of extremely long-lived greenhouse gases in the global atmosphere, atmospheric measurements stations have been our inside man when it comes to keeping track of what is happening in our atmosphere and to what extent human activities are altering its composition.

Perhaps now more than ever, in the light of the IPCC report, we can appreciate the importance of the data that have been collected over decades but also, the efforts of those who have been directly or indirectly involved in this kind of work. Continuing and expanding the measurement networks for these gases is and will be even more vital for a continued understanding of global and regional GHG emission trends.

References

[1] http://www.ipcc.ch/
[2] https://www.bbc.co.uk/news/science-environment-45775309
[3] http://report.ipcc.ch/sr15/pdf/sr15_spm_final.pdf
[4] https://www.carbonbrief.org/analysis-why-scientists-think-100-of-global-warming-is-due-to-humans
[5] https://www.c2es.org/content/main-greenhouse-gases/
[6] https://www.atmos-chem-phys.net/10/5145/2010/acp-10-5145-2010.pdf
[7] https://agage.mit.edu/
[8] https://agage.mit.edu/
[9] https://www.esrl.noaa.gov/gmd/about/aboutgmd.html
[10] http://www.bristol.ac.uk/chemistry/research/acrg/current/decc.html
[11] https://www.co2.earth/co2-ice-core-data
[12] https://www.co2.earth/daily-co2
[13] https://www.theguardian.com/environment/2018/may/16/mysterious-rise-in-banned-ozone-destroying-chemical-shocks-scientists

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This blog is written by Cabot Institute members Eleni Michalopoulou, Dr Dan Say, Dr Kieran Stanley and Professor Simon O’Doherty from the University of Bristol’s School of Chemistry.

Dan Say

Eleni Michalopoulou

Just the tip of the iceberg: Climate research at the Bristol Glaciology Centre

Posted on October 15, 2018April 13, 2023 by janet.crompton

Last week the Intergovernmental Panel on Climate Change (IPCC) released its special report on the impact of global warming of 1.5˚C. Professor Tony Payne – Head of the University of Bristol’s School of Geographical Sciences and Bristol Glaciology Centre (BGC) member – is one of the lead authors on the report, which highlights the increased threats of a 2˚C versus 1.5˚C warmer world. The report also lays out the mitigation pathways that must be taken if we are to meet the challenge of keeping global warming to 1.5˚C above pre-industrial levels.

The core of the report is a synthesis of over 6000 scientific papers detailing our current understanding of the climate system, and here at the BGC our research is focused on the role of the cryosphere in that system. The cryosphere, which refers to all the snow, ice and permafrost on the planet, is changing rapidly under global warming, and understanding how it will continue to evolve is critical for predicting our future climate. This is primarily due to the positive feedback loops in which it is involved, whereby a small change in conditions sets off a sequence of processes that reinforce and amplify the initial change. Despite the name, in the context of our current climate these positive feedback loops are almost always bad news and are responsible for some of the “tipping points” that could lead to runaway changes in the climate system.

I hope this post will give you a quick tour of just some of the research being carried out by scientists at the BGC, studying the way in which mountain glaciers, sea ice and the two great ice sheets of Antarctica and Greenland are responding to and influencing our changing climate.

Ice sheets

My own research examines ice flow at the margins of Antarctica. The Antarctic ice sheet is fringed by floating ice shelves, fed by large glaciers and ice streams that flow from the heart of the ice sheet towards the coast (see Figure 1). These ice shelves can provide forces that resist the glaciers that flow into them, reducing their speed and the amount of ice that enters the ocean. Crucially, once ice flows off the land and begins to float it causes the sea level to rise. My work is in modelling the interaction between ice shelves and the rest of the ice sheet to better quantify the role that ice shelves have in restraining ice loss from the continent. This will help to reduce the uncertainty in our predictions of future sea level rise, as the thinning and collapse of Antarctic ice shelves that we have seen in recent decades looks set to continue.

Figure 1: Schematic of the Antarctic ice sheet grounding line. Image credit: Bethan Davies, www.AntarcticGlaciers.org

To model ice flow in Antarctica with any success it is crucial to know the exact location of the point at which the ice sheet begins to float, called the ‘grounding line’. Research on this within the BGC is being done by Dr Geoffrey Dawson and Professor Jonathan Bamber, using data from the European Space Agency’s CryoSat-2 satellite. Their method determines the location of the grounding line by measuring the rise and fall of the floating ice shelves under the influence of ocean tides. Recently published work from this project has improved our knowledge of the grounding line location near the Echelmeyer ice stream in West Antarctica and this method is currently being rolled out across the rest of the ice sheet [1].

In the Northern Hemisphere, the Black and Bloom project led by Professor Martyn Tranter is studying ice algae on the second largest ice mass on Earth, the Greenland Ice Sheet (GrIS). The large, dark regions that appear on the GrIS in the summer are, in part, down to blooms of algae growing in the presence of meltwater on the ice sheet (see Figure 2). This bloom is darker than the surrounding ice surface and so reduces the albedo (a measure, between 0 and 1, of a surface’s reflectivity). A reduced ice sheet albedo means more of the sun’s energy is absorbed and the surface becomes warmer, which produces more meltwater, and more algae, leading to more energy absorption in a classic example of a positive feedback loop. The aim of the project, a partnership between biologists and glaciologists within the BGC, is to take measurements of algal growth and to incorporate their effect on albedo into climate models. A recent paper from the group, led by Dr Chris Williamson, revealed the abundance and species of microbial life that are growing on the GrIS [2], and this summer the team returned to the field to extend their work to more northerly regions of the ice sheet.

Figure 2: Bags of surface ice collected on the Greenland Ice Sheet showing the change in albedo with (from left to right) low, medium and high amounts of algae present.

Sea ice

Moving from land-based ice and into the ocean, Arctic sea ice is also being studied within the BGC. Regions of the Arctic have warmed at over 3 times the global average during the last century and there has consequently been a dramatic decline in the amount of sea ice that survives the summer melt season. The minimum, summer Arctic sea ice extent is currently declining at 13.2% per decade. Predicting the future of Arctic sea ice is critical for understanding global climate change due to the presence of another positive feedback loop: reduced summer sea ice replaces the white, high albedo ice surface with the darker, low albedo, ocean surface. This means that more solar energy is absorbed, raising surface temperatures and increasing ice melt, leading to more exposed ocean and further warming.

Dr Jack Landy has used remote sensing data from satellites, including CryoSat-2 and ICESat, to measure the roughness of Arctic sea ice and to model the impact that changing roughness has on albedo (see Figure 3). The roughness of the sea ice controls the size of the meltwater ponds that can form on the surface. With less sea ice lasting through multiple summer melt seasons, the trend is for Arctic sea ice to become smoother, allowing larger and larger ponds to form which, again, have a lower albedo than the ice surface they sit on, creating yet another positive feedback loop [3].

Figure 3: Panels a and b are predictions for summer (June to August) Arctic sea ice albedo based upon ice roughness observations made in March of 2005 and 2007 respectively. Panels c and d show the actual, observed summer albedo in those years. Image credit: Dr Jack Landy [3].

Mountain glaciers

A third element of the cryosphere studied at the BGC are glaciers in high mountain regions such as the Andes and the Himalayas. Led by Professor Jemma Wadham, the new Director of the Cabot Institute, this work focuses on the biology and chemistry of the meltwater produced from these glaciers. This summer a team of postgraduate researchers from the BGC – Rory Burford, Sarah Tingey and Guillaume Lamarche-Gagnon – travelled to the Himalayas in partnership with Jawaharlal Nehru University, New Delhi, to collect meltwater samples from the streams emanating from the Chhota Shigri glacier. These streams eventually flow into the Indus river, a vital water source for agriculture and industry in Pakistan. It is therefore crucial to understand how the quality of this water source might change in a warmer climate. Mercury, for example, is precipitated out of the atmosphere by snowfall and can collect and become concentrated within these high mountain glaciers. In the shorter term, if these glaciers continue to melt more rapidly, larger amounts of mercury will be released into the environment and will impact the quality of water that supports millions of people. On longer time scales, the retreat and reduction in volume of the Himalayan glaciers will reduce the amount of water supplied to communities downstream, with huge implications for water security in the region.

Figure 4: Photo from Himalayan fieldwork. Image credit: Guillaume Lamarche-Gagnon

Outlook

This is just the tip of the BGC research iceberg, with field data from this summer currently being pored over and new questions being developed. This work will hopefully inform the upcoming IPCC special report on the oceans and cryosphere (due in 2019), which is set to be another significant chance to assess and share our understanding of the ice on our planet and what it means for the challenges we have set for ourselves in tackling climate change.

References

[1] Dawson, G. J., & Bamber, J. L. (2017). Antarctic grounding line mapping from CryoSat‐2 radar altimetry. Geophysical Research Letters, 44, 11,886–11,893. https://doi.org/10.1002/2017GL075589

[2] Williamson, C. J., Anesio, A. M., Cook, J., Tedstone, A., Poniecka, E., Holland, A., Fagan, D., Tranter, M., & Yallop, M. L. (2018). ‘Ice algal bloom development on the surface of the Greenland Ice Sheet’. FEMS Microbiology Ecology, 94,3. https://doi.org/10.1093/femsec/fiy025

[3] Landy, J. C., J. K. Ehn, and D. G. Barber (2015). Albedo feedback enhanced by smoother Arctic sea ice. Geophysical Research Letters, 42, 10,714–10,720. https://doi.org/10.1002/2015GL066712

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This blog was written by Cabot Institute member Tom Mitcham. He is a PhD student in the School of Geographical Sciences at the University of Bristol and is studying the ice dynamics of Antarctic ice shelves and their tributary glaciers.

Tom Mitcham