Around the world local people are restoring forests, boosting their incomes and sucking carbon from the atmosphere. …Intergovernmental Panel on Climate Change (IPCC) author Joeri Rogelj has calculated that to achieve the Paris Agreement’s aim of keeping global warming to 1.5 degrees Celsius, total future emissions of carbon dioxide (CO2) will probably need to be limited to less than 300 billion tonnes. Bringing CO2 emissions to net zero by the middle of this century would fall far short of that target; it would allow total emissions of around 800 billion tonnes. So we will need to suck CO2 back out of the air. On Rogelj’s estimates, those so-called “negative emissions” would have to amount to between 450 billion and 1,000 billion tonnes.