Advancing satellite technology can improve monitoring of emissions. This will in turn help make policies more robust.
There are now around 2000 satellites in earth orbit carrying out a wide range of tasks. This is about twice as many as only a decade ago[i]. Costs continue to come down, technologies are advancing and more organisations are making use of data, applying new techniques as they do so. As progress continues, satellite technologies are positioned to make a much larger contribution to monitoring greenhouse gas emissions.
Tracking what’s happening on the ground
Satellites are critical to tracking land use changes that contribute to climate change, notably deforestation. While satellites have played an important role here for years, the increasing availability of data is enabling organisations to increase the effectiveness of their work. For example, in recent years Global Forest Watch[ii] has greatly increased the range, timeliness and accessibility of its data on deforestation. This in turn has enabled more rapid responses.
This is now extending to other monitoring. For example, progress on construction projects can be tracked over time. This enabled, for example, monitoring the construction of coal plant in China, which showed that construction of new plants was continuing[iii].
Monitoring operation and emissions
As the frequency with which satellite pictures are taken increases, it becomes possible to monitor not only construction and land use changes, but also operation of individual facilities. For example, it is now becoming possible to track operation of coal plant, because the steam from cooling towers is visible[iv]. This can in turn allow emissions to be estimated.
More direct monitoring of emissions continues to develop. Publicly available data at high geographic resolution on NOx, SOx, particulates and in the near future methane[v] are becoming increasingly available[vi]. For example, measuring shipping emissions has traditionally been extremely difficult, but is now becoming tractable, at least for NOx.
Measuring methane is especially important. Methane is a powerful greenhouse gas with significant emissions from leakage in natural gas systems. Many of these emissions can easily be avoided at relatively low cost, leading to highly cost-effective emissions reduction.
CO2 is more difficult to measure than other pollutants, in part because it disperses and mixes in the atmosphere so rapidly. However, some of the latest satellites have sophisticated technology able to measure CO2 concentrations very accurately[vii]. These cover only quite small areas at the moment but are expected to scale up and allow more widespread direct monitoring. The picture below shows a narrow strip of the emissions from a coal plant in Kansas, based on data from the Orbiting Carbon Observatory 2 (OCO‐2) satellite. These estimates conform well with reported emissions from the plant.
Figure 1: Satellite data showing CO2 emissions for a power plant in Kansas
Note: the red arrow shows prevailing wind direction.
Space agencies around the world are now exploring how such monitoring can be taken further. For example, the EU has now asked the European Space Agency to design a satellite dedicated to monitoring CO2. It is expected to be operational in the 2020s.[viii]
Work is also underway to improve data analysis, so that quantities of emissions can be attributed to individual plants. Machine learning holds a good deal of promise here as a way of finding and labelling patterns in the very large amounts of data available. It is likely soon to be possible to monitor emissions from an individual source as small as a medium size coal plant, taking account of wind speed and direction and so forth.
These developments will make actions much more transparent and subject to inspection internationally. Governments, scientists, energy companies, investors, academics and NGOs can monitor what is going on. Increasingly polluters will not be able to hide their actions – they will be open for all to see. This is turn will make it easier to bring pressure on polluters to clean up their act, potentially including, for example, holding countries to account for their Nationally Determined Contributions (NDCs) under the Paris Climate Agreement.
Improved transparency and robust data are not in themselves solutions for reducing climate change. Instead, they play an important role in an effective policy architecture. And the do so with ever increasing availability and quality. This gives cause for optimism that policies and their implementation can be made increasingly robust.
Adam Whitmore – 12th September 2018
Thanks to Dave Jones for sharing his knowledge on the topic .