Isotopic constraints on past ozone layer in polar ice (ISOL-ICE)

Lead Research Organisation: NERC British Antarctic Survey
Department Name: Science Programmes

Abstract

The ozone layer shields all land-based life forms from harmful ultraviolet radiation; and indirectly influences the climate at the Earth's surface, including temperature and winds, particularly near the poles. Man-made halocarbons, used for example in refrigerators and spray cans, were released to the atmosphere and have caused significant destruction of the ozone layer since the late 1970s, especially above Antarctica during spring-time. Because the use of many halocarbons was banned by the 1989 Montreal Protocol, the ozone layer is expected to recover to the conditions of the 1960s and early 1970s within this century.

However, the thickness of the ozone layer is also influenced by natural causes, which are less well understood and which make predictions of future ozone and climate less certain. Natural causes include variations in the sun's activity, volcanic eruptions, release of biogenic halocarbons and atmospheric circulation. Currently there is very little information on the natural variability of the ozone layer over historic time scales, i.e. before direct observations started in the early 20th century. However, understanding the natural variability of the ozone layer and the underlying causes is necessary to evaluate the effectiveness of climate and ozone policy options. It is also necessary in order to improve predictions of ground level UV radiation, which is recognized as an environmental carcinogen and a major concern for human health.

One way to go back in time beyond the era of modern measurements is the use of proxies measured in polar ice cores. Apart from a recently proposed biomarker there are no quantitative proxies of past UV radiation. Here we propose to measure the isotopes of nitrogen and oxygen in the nitrate ion in polar ice to reconstruct past ultraviolet radiation and therefore the ozone layer. Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons. In the very dry regions of inner Antarctica snow is exposed to sunlight for many months before being buried by snowfall. During that exposure the nitrate in the snow is decomposed by solar UV radiation; during that process the heavier nitrogen isotopes in nitrate are observed to stay preferentially in the snow, whereas the lighter ones escape to the atmosphere above. That fractionation depends on the wavelength and duration of the UV radiation. We hypothesize that once the nitrate in snow is buried at depth, it preserves an isotopic fingerprint of down-welling UV radiation and therefore of the thickness of the ozone layer.

We propose to collect a shallow ice core from East Antarctic Plateau, where low accumulation rates prevail, to develop and apply a new ice core proxy based on the stable isotopes of nitrate, to constrain trends in the ozone layer above Antarctica over the last 1kyr. To do this, we will calibrate the ice core signal with observations of the ozone layer above Antarctica since the 1950s, and then extrapolate that relationship to the more distant past.

Using numerical models we will investigate the underlying causes of the ice core based reconstruction of past variability in the ozone layer. Particular questions we will attempt to answer include: has stratospheric ozone changed in the past; and how did solar variability, natural emissions of halocarbons, or volcanic eruptions contribute to the reconstructed trends?

Planned Impact

The main concrete results of this project are (1) the first ever millennial-scale reconstruction of stratospheric ozone and terrestrial UV radiation at high temporal resolution and (2) analysis of underlying causes of the reconstructed variability. Thus, the main immediate beneficiaries of our research are academic ones. We have identified in particular:

a) atmosphere and cryosphere scientists studying air-snow-ice interactions
b) atmospheric scientists studying stratospheric ozone and natural impacts on its variability at global scales
c) paleoclimate scientists developing proxies in ice cores and other archives for past UV radiation
d) solar physicists investigating the sun's activity in the recent and more distant past

Our route to these people is the normal academic one of scientific papers and conference presentations.

Further beneficiaries include also policymakers (e.g. DECC, DEFRA). This is because assessing the natural variability of the ozone layer beyond the instrument era is critical to evaluate the effectiveness of climate and ozone protection policy options. In particular, natural factors controlling the ozone layer still carry significant uncertainties as stated by the WMO 2014 report on ozone. Therefore an improved understanding of the natural background variability of stratospheric ozone will eventually reduce uncertainties in future ozone projections under climate change and recovery scenarios. Furthermore, the IPCC 2013 Working Group 1 report highlights that large climate forcing uncertainties are associated with solar variability. Narrowing these uncertainties will help us to better understand the various contributions to variability in the historical climate record as well as to reduce the uncertainty range in projections.
Such findings will emerge as the sum of inputs from many proposals (including this one) that will be aggregated by BAS and NCAS. PI Frey has started discussions with the current Science Engagement Lead at DECC on how best to present findings from this and related proposals, with one option being a policy briefing paper led by BAS.

Another aspect of impact is that we as scientists play a role in making science accessible and exciting to the wider public and to students. Regarding this project, BAS has a strong track record for public outreach explaining the science and societal relevance of the ozone layer. BAS is part of the network of Ambassadors for Science with particular emphasis on outreach to schools. For such events, scientists often seek material with a wide appeal. We will gather highly visual footage while working on the East Antarctic Plateau, in particular of the drilling work. Film footage as well as photographs will be made available to all staff within BAS as an outreach resource.

PI Frey is an active STEM ambassador with a strong record of outreach activities related to scientific research in the polar regions. He will follow at least three different routes to achieve impact with a broader audience: 1) through school talks and seminars given to school teachers; 2) through skype lessons given to school children of various age groups, and promoted and implemented by the company Digital Explorer; 3) through a display at the annual Cambridge Science Week. This is a major event where literally thousands of people of all ages gain access to Cambridge University departments to learn about scientific research. PI Frey has set up a highly educative classroom experiment he displays during the Cambridge Science Week engaging hundreds of visitors in a discussion about properties of the gas ozone, both life saving at altitude and life threatening at the ground level. This activity will be further expanded as first results emerge from this project.
 
Title Updating heterogeneous chemistry and surface bromocarbon emissions in UM/UKCA vn10.9 chemistry climate model 
Description Dr Alison Ming has added a set of new heterogeneous reactions and surface bromocarbon emissions to improve the representation of stratospheric ozone in the UM/UKCA vn10.9 chemistry climate model. 
Type Of Material Improvements to research infrastructure 
Year Produced 2018 
Provided To Others? No  
Impact This tool significantly improves the representation of stratospheric ozone which is an important part of the climate system. This will improve future climate modelling. 
 
Title ISOL-ICE field data 
Description The 2016/17 ISOL-ICE field campaign delivered a data set of continuous observations of atmospheric parameters, which are currently being processed and quality controlled. They include continuous high-resolution atmospheric measurements over 1 month (January 2017) of incoming radiation (high-resolution spectrometer), turbulence (sonic anemometer), nitrogen oxides (chemoluminescence detector), ozone, and halogen species (MAX-DOAS). 
Type Of Material Database/Collection of data 
Year Produced 2017 
Provided To Others? No  
Impact Preliminary atmospheric data were presented at a BAS science programme meeting (21/02/2017) and at at the Cambridge-wide Ice Core Forum (28/02/2017),where the strong diurnal cycle of ozone observed at Kohnen station sparked interest and discussion. 
 
Description ISOL-ICE collaboration with AWI (Germany) scientists and logistics 
Organisation Alfred-Wegener Institute for Polar and Marine Research
Country Germany 
Sector Public 
PI Contribution The BAS team collected during the ISOL-ICE field season atmospheric data, including aerosol filter samples (to be analysed for nitrate concentrations and stable isotopes), atmospheric radiation, turbulence, halogenated species, and ozone. In addition, the BAS team sampled surface snow on a daily base as well as 2x 2m-snowp pits for chemical analysis. Furthermore, a shallow core of 120m has been drilled. The ISOL-ICE data set is being shared with AWI scientists as it is being processed.
Collaborator Contribution AWI logistics coordinated much of the planned field activities by inviting PI Frey to a logistics meeting in Bremerhaven held in May 2016 and provided support to ship 32 ice core boxes from the UK to Kohnen station. AWI logistics then hosted the BAS team of 3 for 6 weeks at Kohnen station and provided further support in the field to carry out the planned experiments. Logistic support included the use of a skidoo, fuel to run generators, recovery of 2x 10m cores with a hand auger drill, providing a lab shelter with a 5 kW power line to run ISOL-ICE atmospheric observations, man power to move heavy loads and set up the drill tent, as well as technical support & advice related to shallow coring. AWI scientist Rolf Weller provided aerosol, snow and ice core chemistry data collected in previous years, which were invaluable in helping to plan the sampling strategy for the ISOL-ICE field season. In addition, Weller allowed the use of his set up at Kohnen to carry out atmospheric experiments ( a 5kW power line, byway shelter, 'glove box' to change aerosol filters).
Impact This collaboration was key to a succesful ISOL-ICE field season at Kohnen station / East Antarctica
Start Year 2016
 
Description ISOL-ICE collaboration with Department of Chemistry / Cambridge University 
Organisation University of Cambridge
Department Department of Chemistry
Country United Kingdom 
Sector Academic/University 
PI Contribution Development of model scenarios to test the sensitivity of Antarctic column ozone to volcanic eruptions, solar cycle and oceanic halocarbon emissions over the last 1000 years. Carry out sensitivity studies using the UK Chemistry and Aerosols (UKCA) model. For model validation we provide in situ measurements of air and snow chemistry in East Antarctica during the 2016/17 summer season, as well as constraints of past surface-UV and column ozone in Antarctica from the nitrate stable isotopes measured in an ice core drilled in 2016/17 (analysis in progress).
Collaborator Contribution John Pyle's group provides support to run the UK Chemistry and Aerosols (UKCA) model including code updates to the latest release and set up on NERC's high performance computing facilities (ARCHER, MONSooN).
Impact n/a
Start Year 2016
 
Description ISOL-ICE collaboration with Joanna Haigh / Imperial College London 
Organisation Imperial College London
Department Department of Physics
Country United Kingdom 
Sector Academic/University 
PI Contribution The ISOL-ICE project will provide a reconstruction of the the variability of stratospheric ozone above Antarctica for the past 1kyr. These data are expected in year 3 of the project and will be shared with Haigh and colleagues, who will then be able to test atmospheric models, which describe the interaction between the sun and the upper atmosphere. Haigh attended the ISOL-ICE project kick-off meeting in June 2016 via a telcon link, and was briefed on the theoretical and experimental approach of ISOL-ICE.
Collaborator Contribution Project partner Haigh advised on the modelling approach during the ISOL-ICE project kick-off meeting in June 2016, and follows closely the progress of the project.
Impact n/a
Start Year 2016
 
Description ISOL-ICE collaboration with Joel Savarino / LGGE (Grenoble, France) 
Organisation Laboratory of Glaciology and Environmental Geophysics (LGGE)
Country France 
Sector Academic/University 
PI Contribution The ISOL-ICE team collected a shallow ice core in East Antarctica to be analysed for the stable isotopes of nitrate at LGGE. Additional measurements were carried out at the drill site to constrain the air-snow transfer function of the nitrate stable isotopes. The ISOL-ICE data set is shared with project partner Savarino, starting with the atmospheric observations. At Savarino's lab an existing analytical method was modified to analyse large numbers of ice core samples for nitrate isotopes and much of the observational and theoretical foundation of a new UV ice core poxy was developed. Hence the ISOL-ICE data are very beneficial to Savarino and co-workers to expand their data base to another site on the East Antarctic Plateau.
Collaborator Contribution Savarino provided a high-volume aerosol sampler for the 2016/17 ISOL-ICE field season at Kohnen station. Collection of atmospheric particulate nitrate at the drill site is critical to constrain the air-snow transfer function of the nitrate stable isotopes and compare to similar observations carried out previously at Dome C. Savarino also provides his expertise and advice related to sample collection and analytical set up.
Impact n/a
Start Year 2016
 
Description SOL-ICE collaboration with Department of Geography / Cambridge University (2017 - Still Active) 
Organisation University of Cambridge
Country United Kingdom 
Sector Academic/University 
PI Contribution Dr Alison Ming has designed and run the UM/UKCA chemistry climate model experiments to investigate the variability of stratospheric ozone. The results from the volcanic perturbation experiments are of interest to Dr Anja Schmidt's group and it is likely that the large volume of data generated will be valuable in research beyond the ISOL-ICE project.
Collaborator Contribution Dr Anja Schmidt and her group have add valuable scientific input to the design of the UM/UKCA chemistry climate model experiments as well as providing insight into the interpretation of the model results.
Impact The collaboration is multidisciplinary and involved Geography, Chemistry and Physics.
Start Year 2017
 
Title Updating heterogeneous chemistry and surface bromocarbon emissions in UM/UKCA vn10.9 chemistry climate model 
Description Dr Alison Ming has added a set of new heterogeneous reactions and surface bromocarbon emissions to improve the representation of stratospheric ozone in the UM/UKCA vn10.9 chemistry climate model. 
Type Of Technology Software 
Year Produced 2018 
Impact This tool significantly improves the representation of stratospheric ozone which is an important part of the climate system. This will improve future climate modelling. 
 
Description ISOL-ICE Antarctic field blog 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact During the 2016/17 ISOL-ICE field campaign at Kohnen station BAS team member posted blogs describing travel, living and working conditions in Antarctica. The personal descriptions of carrying out experiments and living under the harsh Antarctic conditions are often inspiring to young people, students and the general public.
Year(s) Of Engagement Activity 2017
URL https://www.bas.ac.uk/project/isolex-isotopic-constraints-on-past-ozone-layer-and-stratosphere-tropo...
 
Description ISOL-ICE Project Web Page 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact The ISOL-ICE project web page is updated regularly to inform science colleagues and also the wider public on the project. Page content includes objectives and aims of the project, a list of team members with their photo and backgrounds, a list of publications, highlights and blog entries from the (a) the 2016/-17 field season in Antarctica and (b) the first part of the lab campaign at the collaborating lab in Grenoble / France
Year(s) Of Engagement Activity 2016,2017
URL https://www.bas.ac.uk/project/isolex-isotopic-constraints-on-past-ozone-layer-and-stratosphere-tropo...
 
Description ISOL-ICE school talk on 9 Jan 2017 via phone with primary school Clifton with Rawcliffe 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact On 9 January students from Yorkshire primary school Clifton with Rawcliffe called the BAS team at Kohnen station during a whole school assembly (500 students) to speak directly to some 'modern polar explorers'. They asked the scientists questions about their science, daily living and working conditions in Antarctica, and how to become a polar scientist. Teacher John Ainscough explained that the students (age 4-11) look during this term at 'Journeys', starting with the incredible adventure of Sir Ernest Shackleton being this year the 95th anniversary of his death. On the day the students took part in activities based around Antarctica: studying maps, or experiencing first hand the hard work of trying to pull a heavy load, such as a sledge, over long distances and how team work is essential in those situations. He added that the children found the comparison between now and a hundred years ago fascinating, and by the end of the day had already messages from a few parents who are saying how much their child was amazed by the whole day.
Year(s) Of Engagement Activity 2017
 
Description Interview for the BBC World Service CrowdScience documentary "Ancient CO2 levels in Antarctic ice cores" 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact In 2017, Holly Winton was interviewed for the BBC World Service CrowdScience documentary "ancient CO2 levels in Antarctic ice cores" http://www.bbc.co.uk/programmes/w3csv3f1 - which went on to win Gold in the audio category of the AAAS Kavli science journalism awards.
Year(s) Of Engagement Activity 2017
URL http://www.bbc.co.uk/programmes/w3csv3f1
 
Description London International Youth Scientific Forum (LIYSF) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Undergraduate students
Results and Impact Since 2016 Dr. M. Frey engages with the London International Youth Scientific Forum, which attracts each year ca 500 students (age 16-20 yr) from all over the world. In 2016 he gave a lecture and led a study day on Polar Research; in 2017 he organised a visit of LIYSF students to the British Antarctic Survey and gave a lecture.
Year(s) Of Engagement Activity 2016,2017
URL http://www.liysf.org.uk
 
Description School Visit (Barton primary school, January 2019 by Holly Winton) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact Primary School talk about ice cores and ISOL-ice - Barton primary school, January 2019 by Holly Winton
Year(s) Of Engagement Activity 2019