The Emit (Earth Surface Mineral Dust Source Investigation) imaging spectroscope, installed on the International Space Station in 2022, was originally designed to study the effects of atmospheric dust on the temperature on the Earth’s surface. According to a recent study, the spectroscope is also capable of identifying large sources of carbon dioxide and methane, which are among the most important greenhouse gases, from space. The data collected by Emit is available for self-service.
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Since the Industrial Revolution in the 19th century, humanity gradually began to produce products on a large scale, resulting in ever-increasing energy requirements. First produced primarily by the combustion of coal (think of the steam engine, for example), the energy production sectors then expanded to include all fossil fuels such as petroleum or natural gas. These fossil fuels are created by the slow breakdown of organic matter (consisting, among other things, of carbon) of living things (plants, bacteria, bacteria, animals, etc.) deep in the soil over several hundred million years. Although these energy sources provide satisfactory performance, the use of fossil fuels today represents a major disadvantage: the production of fossil fuels emits greenhouse gases (such as water, H2O, carbon dioxide, carbon dioxide, CO2 or methane, CH4) that remain in the water at the bottom Atmosphere releases some of the heat into space and warms it.
The greenhouse gas problem
Without these greenhouse gases, the climate on earth would be very inhospitable (the surface temperature of the earth would be around -18°C). On the other hand, an excess of atmospheric greenhouse gases tends to lead to excessive warming of the atmosphere. This is exactly the problem humanity is currently facing: Since the Industrial Revolution, the average surface temperature of the Earth has already risen by 1.5 °C due to anthropogenic greenhouse gas emissions. The trend is still on the rise and is having dramatic consequences for our environment and climate (heat waves, rising water levels, droughts and floods) and even for our lives.
Explanations of the effects of greenhouse gases on temperatures on the earth’s surface, taken from the webdoc. Words from climatologists. © CEA
The two most important greenhouse gases of anthropogenic origin, i.e. emitted through human activity, are carbon dioxide (CO2) and methane (CH4), which are produced, for example, by burning coal or producing and using natural gas. Although scientists have a good understanding of the main types of emission sources (power plants, refineries, etc.), it remains difficult to accurately identify the sources of greenhouse gas emissions. Indeed, carbon dioxide and methane emissions represent a significant source of uncertainty when assessing the global carbon footprint, particularly when emissions arise at small spatial scales (typically less than a kilometer). These uncertainties vary by country (from a few percent for the most transparent countries to tens of percent for countries that are more discreet about their emissions, such as China).
To more accurately calculate the global carbon footprint, scientists have been trying to record carbon emissions from space for several decades. For example, the Tropomi (Tropospheric Monitoring Instrument) and OCO (Orbiting Carbon Observatory) satellites have already been launched with this goal; But scientists were faced with either too little spatial resolution to accurately identify emission sources (they characterized emissions only at a global scale) or too little spatial coverage capacity (they were unable to observe relatively large regions ). A big problem until the July 2022 launch of the Earth Surface Mineral Dust Source Investigation (EMIT) instrument aboard the International Space Station, capable of identifying sources of carbon dioxide and methane emissions at scale, according to a new study published in the journal Science of less than 60 meters.
Observing greenhouse gas emissions from space
Emit is a NASA-made imaging spectroscope that will be deployed aboard the International Space Station (ISS) in July 2022 and will perform visible-light and near-infrared observations. Its initial purpose is to measure the effects of dust suspended in the atmosphere on atmospheric temperature and to identify the emission sources (typically dry areas). According to the team of scientists, these properties also allow the instrument to accurately identify sources of carbon dioxide and methane emissions on our planet’s surface.
To achieve its original goal, the Emit Spectroscope’s first mission aimed to observe dry regions – which emit the most atmospheric dust – such as the Middle East. Using data collected by the spectroscope during the first 30 days of its operation, the research team identified exactly 65 sources of carbon dioxide and methane in the Middle East and Central Asia, mainly coming from the oil and gas sector, wastewater treatment plants and power plants. The data collected by the spectroscope sometimes covered regions whose exact emission rates are poorly known to scientists, exacerbating the uncertainties in assessing the global carbon balance.
In just 30 days, the instrument was able to cover an area larger than South Africa, demonstrating its high potential for spatial coverage while identifying emission sources at scales smaller than 60 meters. Researchers plan to record emissions from more than 1,600 power plants around the world in the first year of the mission. Future Emit greenhouse gas emissions data will be made publicly available.