Report

Teaser, summary, work performed and final results

Periodic Reporting for period 2 - METHID (Observation and Modelling of Radiocarbon in Atmospheric Methane for Methane Source Identification)

Teaser

Emissions of methane (CH4) are the 2nd largest contributor to global climate change, but the attribution of emissions to specific activities currently has large uncertainties. This project advances the state-of-the-art for characterisation of anthropogenic sources of CH4 with...

Summary

Emissions of methane (CH4) are the 2nd largest contributor to global climate change, but the attribution of emissions to specific activities currently has large uncertainties. This project advances the state-of-the-art for characterisation of anthropogenic sources of CH4 with the use of radiocarbon and it creates new directions in atmospheric methane research, with the potential to impact global climate policy and industrial practices over the next 10-20 years.

We are developing an innovative new technique to sample atmospheric CH4 for radiocarbon analysis that simplifies and improves upon previous methods (WP1). Radiocarbon measurements in atmospheric CH4 (14CH4) can identify fossil fuel emissions because radiocarbon is absent in fossil fuels, however it is challenging to perform 14CH4 measurements using current techniques. We will then apply the technique to observe 14C in atmospheric CH4 in the UK and other locations (WP5 and WP6). By close examination of nuclear reactor design and operation, we have produced improved estimates of 14CH4 emissions from nuclear power plants (WP2). We are developing the modelling of 14C in CH4 at regional and global scales to enable the application of 14CH4 observations to estimate the fossil fraction of global and regional CH4 emissions (WP3 and WP4).

Major outcomes of this project will be the introduction and deployment of new approaches to 1. identify fossil vs biogenic CH4 emissions, 2. validate CH4 emissions mitigation policies and 3. understand the response of wetland ecosystems to climate change.

Work performed

The project team has performed work on the work packages 1-4, encompassing laboratory development, analysis of nuclear power plant emissions, and regional and global modelling of radiocarbon in methane. There has been one paper published and one is in review. There have been two conference presentation and several presentations to the public and policymakers about the project (Imperial ERC 10th Anniversary Event, Imperial Fringe Event “Walking in the Air”, Imperial Physics Alumni visit and laboratory tours, and a presentation to civil servants in UK Government).

Final results

The paper published in Radiocarbon provides estimates of 14CH4 and 14CO2 emissions from all nuclear power plants over 1971-2016. It conducts a detailed assessment of the emission factors (emissions per unit power produced) for nuclear power plants in Europe.

The paper in review at Earth’s Future lays out, for the first time, an approach for interpreting observations of radiocarbon in methane to determine fossil fuel and biogenic sources on regional scales. It demonstrates the expected regional signals and their utility using atmospheric transport simulations using the region of California as a test case.

The ongoing laboratory work is developing a new technique for sampling atmospheric methane for radiocarbon analysis. We expect that the new technique will be fully demonstrated in 2019 and then used to conduct atmospheric measurements in the UK and other locations.

Atmospheric measurements of radiocarbon in methane will then be used to determine fossil fuel and biogenic sources on regional and global scales. Ongoing work is also establishing the needed modelling and analysis tools for measurements of radiocarbon in methane as well as for joint modelling and analysis of radiocarbon and stable isotopes in methane.