London GHG

With the adoption of the Paris climate agreement in December 2015, 197 countries have agreed to act to limit the growth in greenhouse gas (GHG) emissions and. As part of this agreement, these countries will provide enhanced transparency in their greenhouse gas emission reporting. An important element of this will be to ensure that there is independent confirmation that signatories are meeting their obligations.

It is widely recognised therefore that monitoring GHGs in the atmosphere is needed to underpin verification methods which can provide critical confirmatory evidence of compliance. Cities, where a majority of human-caused greenhouse gases originate, are ideal testing grounds for different emissions verification methods. For example, multi-million dollar "megacities" projects have recently been developed and deployed in cities such as Los Angeles and Indianapolis, in these cases with emissions being verified using combinations of surface, aircraft-based and space-based instrumentation. Those projects are ground-breaking and have been successful, particularly in engaging local communities and policy makers in the global climate debate. However, the expense and complexity of these multi-platform projects severely limit the scope for rolling out similar efforts across the necessary hundreds of major cities, particularly in the developing world. Furthermore, it is important to rigorously quantify (as well as reduce) the uncertainties in emissions if this information is to be transparent and policy-relevant.

Therefore, in this proposal we set out the following objectives:
1: Adapt and deploy new low cost sensor network technologies to measure CO2, CO and CH4 at precisions and accuracies appropriate for accurate urban-scale emissions evaluation.
2: Develop a high-resolution trace gas "inverse" method for estimating emissions using atmospheric measurements, which quantifies uncertainties more exhaustively than previous studies.
3: Undertake a case study for the first high-resolution emissions evaluation of CO2, and CH4 in and around London using a network of 20 new-generation, autonomous sensor packages.

Recent developments in low cost optical sensors for carbon dioxide (CO2) and methane (CH4) provide the basis for trace level sensor networks for these important greenhouse gases. This proposal is to couple these sensors with recent developments in low cost sensor network calibration and assimilation methodologies to create a GHG emission monitoring network system across London. The observations will be interpreted using state of the art inversion methodologies applied to a combined urban dispersion and atmospheric transport models. We will combine this sensor network with observations from the UK DECC/BEIS network, the Royal Holloway University of London monitoring site, and satellite instruments to produce a integrated comprehensive high-resolution picture of London's GHG emissions.

This project brings together world-leading teams in sensor network technologies and emissions estimation techniques, along with a team of actively engaged stakeholders. The main deliverables are:
- The creation and validation of a low cost GHG sensor network emissions methodology
- The optimisation and deployment of a dense sensor network for GHG monitoring and source attribution across London. - CO2 and CH4 emissions estimates for Greater London for a 12 month period.

London is the main focus of this proposal, however, the overarching aim is to develop and validate a methodology that would have wider applicability, both to other geographic locations and magacities and the extension to other GHGs (e.g. N2O) when suitable sensors become available. In doing so we would provide a tool both to inform GHG mitigation policy and, in the longer term, to provide improved evaluation of expected GHG reductions on the regional scales and below.

There are two main non scientific audiences who will be interested in the outcomes from London-GHG: policymakers; and the public.

The majority of developed countries are required to report detailed, annual GHG emissions reports to the United Nations Framework Convention on Climate Change (UNFCCC). However, at present there is little information with which to validate the estimated emissions from these Annex-1 nations. At a sub-national level, cities, which produce 70% of total energy-related GHG estimates (http://www.ghgprotocol.org/city-accounting), have a direct interest in verifying their GHG emissions if they are to meet the goals they have set themselves, e.g. through membership of the C40 network, as well as making their necessary contributions to national targets.

A major aspect of London-GHG is therefore to make sure that the emission estimates produced are valuable to city authorities in that they can provide a robust, independent evaluation of their own bottom-up estimates and so provide a way to verify the success of their policy measures. To achieve this, interested agencies - BEIS (formerly Department of Energy and Climate Change), the Greater London Authority, and Traffic for London - are included as project partners and will provide their time and expertise to ensure this happens. Representatives from these agencies will form the London-GHG Advisory Group which will meet 1-2 times per year to provide information about their needs. The following analyses and outputs will be provided:
1. Comparisons of London-GHG estimates with bottom-up emissions estimates with the National Atmospheric Emissions Inventory which is a national gridded data set (5 km resolution);
2. Comparison of London-GHG estimates with the London Energy and Greenhouse Gas Inventory which is produced by the GLA on a borough by borough basis;
3. Added-value products (e.g., sectoral estimates) based on the project partners' advice on how the project's products could be adapted to better meet policy need;
4. Information about any large point-source emissions identified in the analysis which might be reduced by immediate action;
5. A framework plan for affordable policy-relevant, city-scale emissions verification in the future for use in London and cities worldwide.

The project partners will also provide insight on other policy needs which might be addressed by deployments of sensor networks. These could include fracking sites and/or landfills.

In addition to presentation and discussion with national and local government agencies in the UK, these results, especially the methodology and outputs (fluxes and comparisons with other estimation approaches), will be presented at international meetings organised under the auspices of C40 and similar organisations. Previous work has been presented to the influential United Nations Environment Programme (UNEP) Technology Panel, which provides guidance on the technical implementation of GHG control measures. We will engage with members of similar panels operating in support of the Framework Convention on Climate Change, providing an important avenue for the dissemination of project outcomes to global policy makers.

The partners will take advantage of all opportunities to promote the research, and the value of science more broadly, to the general public. They have a great deal of experience in this regard having previously been involved in local, national and international media (print, on-line and podcast), in presenting their results in science festivals including the Royal Society Summer Science Exhibition. The type of information collected in this project should make it of particular interest to the general public in London and beyond. Our project partners will assist in this.