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While time is running out to avoid dangerous global warming, the leading US scientific body on Wednesday urged the federal government to launch a research program focused on developing technologies that can remove large amounts of carbon dioxide from the atmosphere. to slow down climate change.
The 369-page report, written by a panel of national academies of science, engineering and medicine, highlights a significant shift. For decades, experts have said countries could prevent large increases in temperature primarily by reducing their reliance on fossil fuels and shifting to cleaner sources such as solar, wind and nuclear.
But at this stage, countries have been so slow in reducing their carbon dioxide emissions that even a vertiginous shift to clean energy is unlikely to be enough.
According to a historic scientific report released this month by the United Nations, it may be necessary to extract much of the carbon dioxide already loaded into the atmosphere to prevent significant additional warming, even though the researchers do not know yet how to do it. economically or on a sufficient scale.
And we will have to do it fast. To achieve the climate goals set out in the Paris Agreement, humanity may have to start removing about 10 billion tons of carbon dioxide from the air each year by mid-century, in addition to reducing industrial emissions. said Stephen Pacala, a climatologist from Princeton, who led the project. sign. It's almost as much carbon as every forest and soil in the world absorbs every year.
"The mid-century is not very far," said Professor Pacala. "Developing technologies and weighing up to 10 billion tons a year is a scary business, which would require a lot of activity. So the time has come now.
Panel members acknowledged that the Trump administration might not find the climate change argument so compelling, as the President disavowed the Paris Agreement. According to Professor Pacala, it is highly likely that other countries will be interested in carbon removal. The United States could play a leading role in developing multi-billion dollar technologies.
Right now, there are many ideas for eliminating carbon. Countries could plant more trees that extract carbon dioxide from the air and lock it in their woods. Farmers could adopt techniques, such as no-till farming, that would retain more carbon in the soil.
Some companies are building "direct air capture" plants that use chemical agents to clean up traces of carbon dioxide in the air, allowing them to sell gas to industrial or industrial customers. ;bury.
But, warned the panel of national academies, many of these methods have not yet proven themselves or face serious limitations. There is very little land available to plant new trees. Scientists still do not know how much carbon can be stored realistically in agricultural soils. And direct air intake plants are still too expensive for mass deployment.
In theory, it may be possible to collect wood or other plant matter that has absorbed carbon dioxide from the air, burn it in biomass power plants as a source of energy, and then capture the released carbon. by burning and bury it deep in the basement, creating a plant that has negative emissions. Although no such facility is commercially operational today, the technology to build it exists.
According to the expert group of national academies, one of the potential problems of this approach is that the land needed for biomass production for these plants could conflict with the need for agricultural land to feed themselves. The group of experts estimated that this method could one day be able to eliminate three to five billion tons of carbon dioxide from the air each year, but perhaps much less, depending on the earth's stresses.
This is far from the 10 to 20 billion tons of carbon dioxide that we may need to get out of the air by the end of the century to limit global warming to about 1.5 degrees Celsius ( 2.7 degrees Fahrenheit), according to the recent United Nations Report. This figure assumes that countries are able to decarbonise their energy and industrial systems almost entirely by 2050.
According to the UN report, tens of millions of additional people could be exposed to heat waves and water shortages, and the world's coral reefs could disappear almost entirely.
The panel of national academies recommended a dual strategy. The United States could put in place programs to begin testing and deploying ready-to-use carbon removal methods, such as emissions-based biomass plants, new forest management techniques or carbon culture.
At the same time, federal agencies should fund research on carbon removal techniques at an early stage to determine if they could ever be ready for widespread use.
For example, scientists have long known that certain minerals, such as peridotite, can bind to carbon dioxide in the air and essentially transform gas into solid rock. Researchers in Oman are exploring the possibility of using the country's vast mineral deposits to remove carbon, but the question remains whether it can be done on a large scale.
In its report, the task force presented a detailed research program that could cost billions of dollars. But since carbon removal could "solve a substantial part of the climate problem," says the report, these costs are modest. In comparison, the federal government spent $ 22 billion on renewable energy research between 1978 and 2013.
External experts welcomed the report as a sign that carbon removal is finally at the center of discussions on how to tackle climate change.
"We are moving from the early stage of" What is carbon? "Determining the specific steps to take to achieve these large-scale solutions," said Noah Deich, executive director of the Carbon180 group, who recently began an effort to bring together researchers and companies to help bring the technology to market. of carbon removal technologies.
The panel of national academies cautioned however about one of the potential drawbacks of research on carbon removal. This could create a "moral hazard", in which governments may find it less urgent to reduce their own emissions if they thought giant carbon-cleaning machines would soon save the day.
To this end, the group of experts pointed out that the elimination of carbon, if developed, could only be part of a larger strategy to fight global warming. . The report stresses that "reducing emissions is essential to solve the climate problem".
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