Countries that rely too heavily on carbon removal in their climate plans could violate international law, warns a new paper.
To keep warming to 1.5 degrees C, the world must cut emissions nearly in half by the end of this decade and zero out emissions by mid-century, but given the extraordinary challenge of overhauling the global energy system in such short order, experts say that it will be necessary to draw down emissions by planting trees, for instance, or deploying machines that soak up carbon dioxide.
“There is no way to meet the Paris Agreement target of limiting global warming to 1.5 degrees without removing some carbon dioxide from the atmosphere,” said Rupert Stuart-Smith, a professor of climate law at the University of Oxford and lead author of the paper. But, he said, climate plans that do too little to cut emissions in the short term and lean too heavily on carbon removal over the long term could breach international law.
Such plans may allow warming to surpass 1.5 degrees C, necessitating the use of carbon removal to bring temperatures back down. Today’s leaders would burden future generations both with more intense warming and with the difficult task of cleaning up excess emissions, in violation of the Paris Agreement, which calls for “fair” and “ambitious” climate commitments “in line with the best available science.”
Even climate commitments that are consistent with 1.5 degrees of warming “may still be inconsistent with international law norms,” owing to their heavy reliance on carbon removal, said the paper, published in Science. Carbon removal remains largely unproven at scale and over the long term. Countries may fail to drawn down emissions if, for instance, carbon capture technology remains too costly. Or they may see their efforts undone if, say, newly planted forests succumb to worsening drought and fire.
Without legal guidance on the use of carbon removal, said study coauthor Joeri Rogelj, of Imperial College London, governments may face court challenges for their overreliance.