Over the last several decades, governments have collectively pledged to slow global warming through accords such as the Kyoto Protocol and the Paris Agreement. Despite the ratification of these agreements by a large number of countries, the atmospheric concentration of CO2 continues to rise.
At the present rate, the remaining quantity of CO2 emissions to limit temperature rise to 1.5°C approximately within the next ten years will soon be used up. If this 'carbon budget' becomes depleted before net-zero emissions are achieved globally, it is likely that we will have to remove one tonne of CO2 from the atmosphere later in the century for every additional tonne of CO2 that we emit after this point. In other words, continuing on the current trajectory will result in building up a carbon debt.
The authors of the study, titled 'Operationalising the net negative carbon economy' and published in Nature, point out that the net-zero pledges made...