21 April 2021


Blog, Earth Observation, Media Updates, Space

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A Copernicus mission to help address climate change

In 2015, experts outlined a vision and roadmap for a European system to monitor ‘anthropogenic’ CO2 emissions – particularly those associated with burning fossil fuels. The aim was to develop a system that would provide accurate data to help assess the effectiveness of policy measures to combat climate change. The solution they devised was to integrate in-situ measurements and satellite observations with detailed computer simulations to model CO2 emissions at local and national scales.

The satellite component is known as the Anthropogenic CO2 Monitoring (CO2M) mission and is slated to contribute data in time for the second Global Stocktake in 2028 under the Paris Agreement. RHEA’s Yasjka Meijer works at ESA as the CO2M mission scientist and authored the CO2M mission requirements document.

The mission’s name is a bit of a mouthful. Why is it called that?

Anthropogenic refers to human influence or ‘man-made’, and it’s really important that we distinguish this mission in that respect compared with any other mission measuring CO2. Eventually the mission may be renamed in line with the other Sentinel satellites within Copernicus, but for now the name describes exactly what it’s designed to do.

What is so important about monitoring CO2 via satellite?

Every 5 years there is a Global Stocktake of CO2 emissions as part of the Paris Agreement. In general, the approach is to make estimates calculated from oil imports. However, in the Paris Agreement, the transparency framework calls for actual measurement-based evidence.

Having data at city, national and wider regional levels may support countries in evaluating the effectiveness of their strategies to reduce CO2 emissions and possibly redefining their Nationally Determined Contributions. In addition, this data will be independent, so can be used to verify nationally reported figures.

We will also be able to measure methane, which is the second strongest greenhouse gas released due to human activities.

Average nitrogen dioxide worldwide levels gathered by the Copernicus Sentinel-5P satellite, April-September 2018. © Contains modified Copernicus data (2018), processed by KNMI.
Average nitrogen dioxide worldwide levels gathered by the Copernicus Sentinel-5P satellite, April-September 2018. © Contains modified Copernicus data (2018), processed by KNMI.

Is it straightforward to measure CO2 from space?

Measuring CO2 from space is very easy, but it is hard to disentangle man-made emissions. That is because these emissions tend to be very intense but only over a relatively small fraction of land in each case – usually over cities and locations such as power plants and industrial facilities. The levels of emissions can also change quite significantly during a single day, for example due to traffic emissions from rush hours or heating and cooling of homes.

The number of satellites in the overall constellation therefore has to take all of this into account. Currently we expect to have three low Earth orbit satellites in the constellation.

What instruments will be on board the satellites?

You cannot get an accurate measurement of anthropogenic CO2 just by using one instrument. Instead, the proposal is to make four different observations. The main payload on each satellite will be a ‘pushbroom’ imaging spectrometer that operates in three spectral bands. From those we can determine the amount of CO2 in the atmosphere.

Then we need to make measurements of NO2, which acts as a tracer or tell-tale of high-temperature combustion – cars, heating in houses, and power plants all produce NO2. If you see a plume of NO2 with a much higher signal compared to its background, you know where to look for the CO2. Next, one of the most annoying things is the interference from clouds and aerosols, so there will be two dedicated instruments to measure these.

What is the timescale for this project?

The EC wants us to contribute to the Global Stocktake, which is part of the Paris Agreement. However, the data for 2028 will be measured in 2026, requiring us to have at least one satellite ready by September 2025 and launched that year in order to leave enough time for a commissioning phase before we start collecting data for the Stocktake.

This is relatively quick for such a mission, but ESA is in a good position to achieve this.

What is the biggest challenge overall for the CO2M mission?

For the mission itself, the development time is most demanding. The biggest and most difficult challenge for the instruments is to be highly accurate and to have a very high spatial resolution at the same time.

Measuring CO2 in itself is relatively easy, but to measure it with the level of accuracy required is not. We are looking at capturing this data with better than 0.18% precision.

The need for accurate data on CO2 is widely recognised. Using Copernicus to monitor CO2 emissions was specified at the highest level in the European Commission last year when it was explicitly mentioned by the President of the EC as a target for the relevant EC Commissioner.

Find out more

This blog post is based on an article in OpenSpace 26, RHEA’s thought leadership magazine published in July 2020.