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Under the 2015 Paris Agreement to limit global warming, countries must measure and report progress towards their committed reductions in emissions. They regularly present their greenhouse gas inventories, detailing the emission sources and the removal or ingestion of gases within their borders. These are then reviewed by technical experts.
The accounting process aims to provide transparency and build trust, but it takes time and figures can be far from precise.
What if changes in emissions of carbon dioxide, the main gas that warms the planet, could be reported more accurately and quickly? This can be extremely useful as the world tries to limit warming.
Climate Trace, a new project that former Vice President Al Gore unveiled at an event alongside the COP26 climate summit in Glasgow on Wednesday, uses artificial intelligence and machine learning to analyze satellite imagery and sensor data to reveal what he says are accurate emissions estimates. . in near real time.
But NASA researchers and colleagues reported Wednesday what they call a milestone towards a different goal: measuring real changes in carbon dioxide concentrations in the atmosphere as countries take steps to reduce emissions.
By linking satellite measurements of CO2 to an Earth systems model, the researchers said they were able to detect small drops in the atmospheric concentration of the gas in the United States and other regions as a result of coronavirus lockdowns in early 2020.
By some estimates, the decline in economic activity due to lockdowns, 10 percent emission reduction even more, but emissions have since returned. These reductions may seem large, but they meant only a minor change in the concentration of CO2 in the atmosphere, which is now more than 410 parts per million.
The researchers were able to detect a decrease of about 0.3 parts per million during the quarantine periods.
“We believe this is a turning point,” said Brad Weir, a research scientist at NASA’s Goddard Space Flight Center and lead author of a paper describing the study published in the journal Science Advances.
The Orbiting Carbon Observatory-2 satellite was not designed to measure changes in human-induced CO2 emissions. Instead, it was necessary to see how large-scale natural climate models such as El Niño and La Niña affected the CO2 concentration. The satellite measures the CO2 in the air column between its position and the Earth’s surface and can detect additional or reduced levels of gas before it mixes homogeneously in the atmosphere.
“We were lucky in early 2020 a strong El Nino effectDr. Weir said, noting that a stronger El Niño signal would mask the human-induced one.
Several additional CO2 measurement satellites are planned to be launched in the coming years. Dr. “We believe it is possible to monitor emissions through space-based observations, as we have better and better observing capabilities,” Weir said.
Johannes Friedrich, a senior associate working on emissions accounting at the World Resources Institute research organization, said current measurements of emissions, particularly from fossil fuels, are reasonably accurate. Measurements are based on reporting of human activities, such as the operation of a particular coal-fired power plant; Calculating emissions from burned coal is relatively straightforward and straightforward. “We pretty much know where the emissions are coming from and most countries are recording them,” said Mr. Friedrich.
Emissions from agriculture and deforestation present greater uncertainties. For example, estimates of greenhouse gases emitted by cattle are only estimates. And emissions from deforestation can vary depending on the degree and extent of clearing, among other factors.
Mr. Friedrich, who was not involved in the research, said he thinks satellite-based measurements could potentially work in the future. “There are still some pretty big challenges right now,” he said.
“For example, you will need very regular measurements at very good resolution and very good coverage of the entire United States,” he said. “And it’s still very difficult.”
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