The Science of Measuring Greenhouse Gas Emissions and Carbon Accounting

About

The UNSW ESSRC Greenhouse Gas (GHG) Measurement team is conducting world-leading research to measure atmospheric concentrations of carbon dioxide, methane and nitrous oxide, and to quantify emission rates from urban and industrial facilities, mines, agricultural regions and natural landscapes. Our research aims to identify GHG mitigation opportunities and establish baseline emissions for Intergovernmental Panel on Climate Change (IPCC) source categories to support verification of national inventories and track net zero progress. This work informs the development and evaluation of greenhouse gas policies and emissions reporting frameworks, contributing to the United Nations Sustainable Development Goals (SDGs), UNSW’s Environmental Sustainability Plan, and UNSW Science's Pact for Impact. Our team works closely with governments and international organisations, including the United Nations Environment Programme (UNEP), the Australian Government and state government departments. In addition to this applied, policy-focused research, we are advancing scientific understanding of carbon exchange among the major carbon pools in the Earth system.

Greenhouse Gas Sources

Oil and Gas GHG emissions contribute approximately 22 Mt CO₂-e annually towards Australia’s UNFCCC/Paris Agreement inventory. Australia is developing new gas-production capacity, particularly in Western Australia, Queensland and the Northern Territory, while production from several mature east-coast fields, such as those in Bass Strait, is declining. Since 2018 we have worked closely with the United Nations Environment Programme International Methane Emissions Observatory (UNEP IMEO) to quantify methane emissions from this sector. We also contributed to the world’s first airborne study to independently quantify and verify methane emission rates from coal seam gas production.

Coal mining and handling contributes approximately 25 Mt CO₂-e towards Australia’s UNFCCC/Paris Agreement inventory. The International Energy Agency (IEA) estimates that coal provides approximately one third of global energy generation. Estimating the true rate of GHG emissions from open-cut coal mines remains controversial. We are currently undertaking ground-, airborne- and satellite-based measurements of GHG emissions in the Hunter Coalfields to identify all sources of methane associated with coal production with the aim of quantifying the true rate of emissions from coal production.

Urban emissions are an easy and large mitigation opportunity. Annually up to 4% of gas distributed through urban gas networks is lost to the atmosphere. Our research maps these urban GHG emission sources so that they can be reduced or eliminated. There are numerous opportunities to map and reduce urban emissions from gas networks, landfills, wastewater facilities and the sewerage networks. We are working closely with the NSW EPA to develop methods to measure and quantify emissions from active and historical landfills.

Emissions from agriculture, enteric fermentation and manure management annually contribute approximately 76, 59 and 4 Mt CO2-e to towards Australia’s UNFCCC/Paris Agreement inventory, respectively. We have measured emissions from grazing cattle, feedlots and beef processing facilities as part of projects for UNEP and SmartSAT CRC. This research compared methane emission estimates derived from atmospheric observations with those calculated using traditional IPCC and Australian Government-approved bottom-up, emission-factor-based methods.

Source Attribution Using Isotopes

Different methane sources have distinct chemical and isotopic signatures that can be used to identify where emissions come from. We specialise in characterising methane sources by collecting air samples from emission plumes and analysing their isotopic composition. This allows us to distinguish between methane sources such as coal seam gas, cattle and landfills. We then use these source signatures to sense-check bottom-up emission inventories by modelling the emission rates and atmospheric mixing of methane from multiple sources.

Government Submissions and Policy Reviews

The effectiveness of climate policy in systematically reducing GHG emissions is contingent upon the accurate quantification of emissions released to, and removals from, the atmosphere. Our research bridges atmospheric science and emissions policy by evaluating legislated methods used to quantify major methane emission sources worldwide, including those applied under Australia’s National Greenhouse and Energy Reporting legislation and the Safeguard Mechanism.

Our projects provide scientific evidence to governments and regulatory bodies on best-practice approaches for measuring, reporting and independently verifying emissions. This work supports the refinement of existing policies, the development of improved emissions-reduction frameworks, and adoption of mitigation technologies needed to accelerate progress towards the goals of the Paris Agreement.

Research Staff

Professor Bryce Kelly

Professor Bryce Kelly is an Environmental Scientist with extensive experience in groundwater, greenhouse gas source attribution, determining the rate of greenhouse gas emissions from facilities and carbon accounting. His research is focused on providing defensible scientific evidence about groundwater, soil and greenhouse gas sources and sinks, to guide policy and legislative developments. He has undertaken projects on traditional oil and gas developments, coal seam gas (CSG) production impacts, coal mining and agriculture. Research he has led is cited in government legislation (water sharing plans), NSW Chief Scientist and Engineer reports, government inquiries, Environmental Impact Statements on CSG developments, public submissions on CSG developments, and Australia’s National Inventory submission to the UNFCCC. The international impact of his research is reflected in citations by the United Nations, UNEP, Food and Agriculture Organization of the United Nations, IPCC, World Meteorological Organization, UK Government, Asian Development Bank, OECD, and others. He also helps UNSW contribute to the UN Sustainable Development Goals.

UNSW Profile, Google Scholar, ORCID

Contact email: bryce.kelly@unsw.edu.au

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Dr Stephen Harris, Senior Postdoctoral Fellow

Stephen Harris is a greenhouse gas measurement scientist specialising in atmospheric measurement and the independent quantification and verification of greenhouse gas emissions. He completed his PhD at UNSW in 2021 under the supervision of Assoc. Prof. Bryce Kelly and Dr Dioni Cendón (ANSTO), investigating nitrogen cycling and nitrous oxide across groundwater, surface water and atmospheric systems. During his PhD, he undertook an Endeavour Research Fellowship at Empa, Switzerland, developing calibration approaches for greenhouse gas laser spectrometers. Dr Harris subsequently worked with UNEP’s International Methane Emissions Observatory (IMEO), coordinating and analysing airborne methane measurement studies in Australia and internationally. He led and first-authored the Nature study quantifying methane released by the 2022 Nord Stream pipeline leaks. At UNSW, his research integrates airborne, satellite and ground-based measurements to quantify methane emissions, evaluate reported emissions and inform emissions reporting and climate policy. He currently leads measurement and analysis of coal-mine methane emissions in the Hunter Coalfields and serves on the Scientific Advisory Committee for the NSW Greenhouse Gas Monitoring and Verification Program, providing expertise in atmospheric measurement and emissions quantification. He is also developing new drone-based approaches for methane quantification.

ORCID | Google Scholar | LinkedIn

Contact email: s.j.harris@unsw.edu.au

Tarra Brain, PhD candidate

Tarra Brain is a PhD candidate with the UNSW GHG Measurement team under the supervision of Prof. Bryce Kelly and Dr Stephen Harris. Her research focuses on the link between GHG measurement and Australia’s climate policy, providing policy analysis insights at the state and federal level. She currently contributes peer-reviewed research and public submissions on legislated emission estimation methods for coal mines and emission reduction policy. Tarra holds a BEng in Chemical Engineering (First Class Honours) and a MEng Environmental Engineering, with experience working as a climate policy and emissions quantification consultant in the private sector.

Government Advisory and Expert Roles

Expert Panel on Atmospheric Measurement of Fugitive Methane Emissions in Australia (Prof. Kelly)
Scientific Advisory Committee for the NSW Greenhouse Gas Monitoring and Verification Program (Prof. Kelly and Dr. Harris)

Recent Journal Publications and Submissions

2026	Aircraft measurements across 17 Bowen Basin coal mines reveal where Australia's national methane inventory methods perform well—and where open-cut mine estimates need improvement. Harris et al. (2026), Atmospheric Chemistry and Physics
	Analysis of Australia's Safeguard Mechanism examines how cap-and-trade policy is shaping emissions reduction in the coal sector. Brain, Harris & Kelly (2026), Climate Policy
	Our latest submission to the Australian Government addresses how fugitive methane emissions from open-cut coal mines should be estimated under the National Greenhouse and Energy Reporting Scheme. 2026 NGER Method 2 submission
2025	The most comprehensive assessment of the 2022 Nord Stream pipeline leaks quantified the largest recorded anthropogenic methane release. Harris et al. (2025), Nature
	Two independent airborne techniques found methane emissions from an Australian open-cut coal mine substantially exceeded estimates based on emission factors, highlighting the value of independent measurement and verification. Borchardt et al. (2025), Environmental Science & Technology Letters
	Our submission to the Australian Government's NGER review identified transparency, uncertainty and regulatory guidance as priorities for improving the estimation of fugitive methane emissions from open-cut coal mines. 2025 NGER Method 2 submission / consultation

Selected Media

UNSW Newsroom (2025) Coal mine methane emissions much higher than previously reported

The Guardian (2025) Methane emissions from Queensland mine may be gross underestimates

Sydney Morning Herald (2024) Satellite to Sniff Out Fugitive Emissions

UK Financial Times (2021) Bowen Basin Coal Mine Emissions

ABC News (2021) Surat Basin - Coal Seam Gas Study

ABC 7:30 (2021) Surat Basin- Coal Seam Gas Study – video

The Conversation (2016) Coal Mine Emissions

Sydney Morning Herald (2020) Sydney Urban Gas Leaks

Sydney Morning Herald (2020) Narrabri Gas Project

The Saturday Paper (2015) Coal Seam Gas

Australia Geographic (2012) Coal Seam Gas and Fracking

Honours, Masters, and PhD Supervision

We are always happy to have students join the research team. We can offer a diverse range of research topics and training focused on the measurement and modelling of greenhouse gas source emission rates. We are often out in the field undertaking car- and aircraft-based surveys across different areas of Australia, and analysing and modelling ground-breaking satellite GHG datasets that are making real-world impacts by informing and verifying Australia’s GHG inventories.

The diverse skills learned by our graduates are in high demand both nationally and internationally, with former students finding engaging careers in government, industry, international organisations and research. We have a strong supervision track record, having mentored 12 PhD, 3 Masters by Research, 26 Masters by Coursework and 22 Honours candidates to completion and successful careers.