U.N. estimates of the amount of carbon that humans can remove from the atmosphere are deeply unrealistic, scientists warn. A new paper offers more plausible carbon removal targets.
The U.N. Intergovernmental Panel on Climate Change estimates the world could draw down 11.3 billion metric tons of carbon dioxide yearly by planting fast-growing crops, burning those crops to generate power, and then capturing the resulting emissions. The world could scrub an additional 10.1 billion metric tons from the atmosphere each year by cultivating forests. But the land needed for new farmland and forest in these scenarios would cover an area three times the size of China.
“It is obvious that this is by no means feasible,” said Felix Creutzig, a researcher at Technical University of Berlin and coauthor of the new paper. Devoting such a vast area to carbon removal would mean destroying wilderness, encroaching on needed farmland, and trampling Indigenous land rights. By putting forward these unrealistic estimates, he said, the U.N. is encouraging politicians to do too little to cut emissions “and to promise great things in terms of carbon removal instead.”
The new paper, published in Science, estimates the world could sustainably remove, at most, 2.9 billion metric tons of carbon dioxide annually by capturing emissions from burning crops and 3.8 billion tons annually from growing forest.
While the U.N. figures reflect what is technically possible, “The real scope of possibilities is definitely smaller,” Creutzig said.