Technology to remove the planet-warming greenhouse gas CO2 from the atmosphere must urgently be ramped up, leading climate experts say in a new report.
Drastic reductions in carbon dioxide emissions will not be enough to limit global warming, scientists say.
Nature alone cannot remove enough pollutants from the air.
CO2 is the most important gas for warming the planet and is emitted when fossil fuels such as natural gas and oil are burned.
“To limit warming to 2C or below, we need to accelerate emissions reductions. But the findings of this report are clear: we also need to increase carbon removals,” said lead author Dr Steve Smith from the University of Oxford. “Many new approaches with potential are emerging.”
Scientists agree that the world is warming primarily because carbon dioxide emissions (estimated at 33 billion tons in 2021) far outstrip the amount being removed (this report suggests 2 billion tons per year).
Global temperatures are projected to rise until emissions and removals reach equilibrium (so-called “net zero”).
But getting there isn’t easy. The latest U.N. climate report says that to fully achieve “net-zero emissions,” some carbon dioxide needs to be removed, so-called “negative emissions,” to compensate for sectors that are not easily decarbonized.
Currently, almost all CO2 removal in the world occurs through natural processes. This is primarily plants and trees absorbing carbon dioxide from the air, and soil absorbing and storing it.
But nature has a limit to what it can do. For example, how much land in the world can actually be given up to forests? Some optimistic scenarios suggest that natural CO2 removals could double by 2050, but still only about 4 GtCO2 per year.
The new report, titled “The State of Carbon Dioxide Removal,” says that limiting and reducing global temperatures in the future will require investment in the development of technological solutions now.
The methods it references are all fairly new and in various stages of development and deployment. Together, they currently account for only a small fraction of the world’s carbon dioxide removals.
One, called BECCS, involves the incorporation of CO2 capture into biomass-based power generation, in which organic matter, such as crops and wood pellets, is burned to generate electricity. Other options include: large-scale facilities that extract carbon from the air before storing it in the ground; using specially treated charcoal (biochar) to lock up the carbon; and “enhanced rock weathering” – roughly based on carbon that occurs through natural erosion remove.
The use of carbon dioxide removal technologies is not without criticism. Some activists doubt they are cost-effective, and worry they could be an excuse to delay and postpone the transition from using fossil fuels.
The report stresses that removing carbon dioxide should not be seen as a “panacea” to combat climate change, but that meeting the UN’s climate goals requires both technology and nature to reduce greenhouse gas levels.
All of this assumes that global carbon dioxide emissions from burning fossil fuels will drop as rapidly as promised at numerous climate summits. So far, annual emissions have not started a downward trend.
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