Open Methane's First Results Build the Urgent Case for Improved Emissions Measurement
Satellites observe more methane near emission hot spots than expected from the National Inventory.
Introduction
To manage and mitigate Australia's emissions effectively, accurate monitoring is essential. The authority tasked with collating and reporting Australia's national methane emissions is the Federal Department of Climate Change, Energy, the Environment and Water (DCCEEW), which reports figures quarterly in its National Greenhouse Gas Inventory. Current methods for calculating these figures rely heavily on self-reporting from industry, often using outdated methods. This approach has raised concerns regarding the accuracy and transparency of the reported data.
The primary issue with self-reporting is its inherent lack of independent verification. Without third-party measurement, there's a significant risk that reported emissions may not fully represent actual methane emissions. Discrepancies can arise from unintentional underestimations, or from coarse estimation methods which do not take into account variability or local factors. Verification makes it clear when estimation techniques fall short so they can be adapted to adequately reflect local circumstances.
Recent advances in remote sensing technologies, such as satellite measurement, have begun to provide a more comprehensive and accurate picture of methane emissions globally. Open Methane uses observational data from the Sentinel 5P satellite and an atmospheric pollution model, to develop detailed, grid-level analysis of methane emissions and concentration across Australia. Our aim is to enhance evidence-based understanding of methane in Australia, support industry initiatives for reducing and mitigating emissions and contribute to informed policy discussions to meet Australia’s obligations under the Global Methane Pledge.
First results
Open Methane’s initial results represent a significant development in our understanding of methane emissions in Australia. By applying the Open Methane model to historical data from July 2022, we have found that Australia's official data may be significantly underestimating methane levels near identified emission hotspots.
In contrast, our analysis of satellite observations more closely aligns with an alternative dataset provided by Climate TRACE, reporting 2.5 times higher methane emissions compared to official statistics.
This finding not only casts doubt on the accuracy of Australia’s self-reported methane estimates but also underscores the potential for significant under-reporting of emissions.
The discrepancy between the official data from the National Inventory and the atmospheric measurements as observed by the Sentinel 5P satellite indicates a large uncertainty in current reporting methods, suggesting that policies based on these figures may be inefficient or ineffective in addressing methane’s impact on climate.
How the results were calculated
A core component of the Open Methane model involves running emissions estimates through atmospheric simulations to determine the geographical spread of methane concentrations. This allows us to map predicted methane distributions and compare them against satellite measurements, which detect actual atmospheric concentrations.
To test this component of our model, we first compiled a list of the forty sites in Australia with the highest expected emissions. For each site, we looked at two separate sources of data for Australia’s methane emissions: the DCCEEW’s National Inventory figures, and from data supplied by Climate TRACE.
Distributing Emissions on the Map
These two sources of emissions data vary significantly in their geographic assignment of estimates. While Climate TRACE offers granular, site-specific emission estimates, the National Inventory provides broader, aggregated data by state and industry.
To address this for our modelling, the National Inventory emissions were distributed based on the proportion of emissions each site contributed in the Climate TRACE dataset. By distributing the data in this way, we provided a normalised representation of methane emissions for both datasets to use as inputs to the Open Methane model.
A detailed First Results Methodology report will be available soon, offering an in-depth look at how we distributed emissions.
Local enhancement
After running the two emissions estimates through our atmospheric model to simulate methane concentrations, we wanted to verify that the simulation demonstrated additional concentrations of methane at emission sources compared to background levels.
To achieve this, we calculated the average concentration within a 20 km radius of each hotspot to establish its ‘local concentration’. Then we measured the average concentration within a roughly 100 km radius around the location, ignoring the local concentration area.
Lastly, we derived a single value by subtracting the concentrations from the larger area from the local concentrations, thereby giving us the ‘local enhancements’ for the site being examined. This should be a proxy for how much more methane is in the air at this site than in the surrounding area.
With the two simulated local enhancements at each emissions hotspot, we could then compare against local enhancements calculated from historical observations from the Sentinel 5P satellite (ie. the true amount of methane in the atmosphere).
A more extensive explanation of this process, including data, will be available in the First Results Methodology.
Understanding the Results
The question was: which of the two datasets of emissions, the National Inventory or Climate TRACE, would more closely reflect the methane concentrations observed by satellite? The scatter plot below shows our results.
Each point on the graph corresponds to one of the forty highest-emitting sites, and is plotted by its simulated methane concentration (along the X-axis) and observed methane concentration (on the Y-axis) for each individual site.
Each of the forty sites is represented twice – those representing the National Inventory emissions estimate are orange, while those representing Climate TRACE estimates are in red.
The clustering around each inventory’s trend line is visible but not perfect. Imperfections arise from uncertainties in the distribution of emissions, the atmospheric model, or the satellite observations.
However, the trend lines are so distinct, and the simulation based on the Climate TRACE data fits the satellite observations so much better, this gives us a high degree of confidence that the true emissions are higher than those estimated in the National Inventory.
This result is significant because it underscores the potential gaps in the National Inventory’s reporting system. By revealing these discrepancies, Open Methane not only validates the use of advanced satellite technology in emissions monitoring, but also sets a precedent for revising emission estimates to better reflect the actual levels. This could lead to more informed and effective policy decisions and climate action strategies.
Open, accessible, auditable data
All data utilised in this analysis adheres to the Open, Accessible, Auditable Data framework, reflecting Open Methane’s commitment to transparency and collaboration. We invite the research community to scrutinise and critique these findings to enhance our collective understanding of Australia’s methane story.
For a more comprehensive understanding of the methodologies used to obtain these findings, please check back soon for our detailed First Results Methodology article. This document will expand on the techniques and data analysis processes employed in this investigation.
These initial results mark the beginning of Open Methane’s testing phase. As we refine our methods and expand our analysis, we will continue to share more detailed insights into various facets of Australia’s methane emissions. Upcoming features on the Open Methane platform, including an interactive map of emissions, advanced data visualisation tools and personalised alerts for emissions tracking, will greatly enhance the accessibility of satellite-detected methane observations.
The Open Methane project’s initial findings underscore the necessity for advancements in the precision of methane monitoring to fulfil Australia’s international environmental commitments. By integrating satellite data with atmospheric modelling, this initiative provides a scientifically robust framework for accessing methane emissions more accurately, enhancing our understanding of emissions in Australia and supporting our emissions reductions strategies.