Overly optimistic emissions accounting is hindering attempts to tackle climate change, with some countries and companies using natural carbon sinks like oceans and forests in their accounting to meet net-zero goals. "We now have a situation that by maximizing our use of carbon offsets, so to speak, we could potentially pretend we are on the path to net zero by 2050 and actually do nothing at all for 15 years," says University of Oxford climatologist Myles Allen.