Redefining net zero won't stop global warming, scientists say

It is generally expected that the achievement of net zero global emissions of carbon dioxide (CO ₂ ) with decreasing emissions of other greenhouse gases will stop global warming. CO emissions ₂ they will continue to drive warming until it is fully balanced by active anthropogenic CO removal ₂ . However, for practical reasons, many GHG accounting systems allow some "passive" absorption of CO to be included in the definition of net anthropogenic emissions ₂ , such as increased vegetation growth due to CO fertilization ₂ . By including passive CO absorption ₂ would nominally net zero emissions not stop global warming, undermining the Paris Agreement. Here we discuss measures to address this problem to ensure that the use of residual fossil fuels does not cause further global warming: land management categories should be disaggregated in emissions reports and targets to better separate the role of passive CO sinks ₂ ; if possible, the claimed removal should be in addition to passive income; and targets should recognize the need for Geological Net Zero, which means one ton of CO ₂ permanently renewed on the solid Earth for every tonne still generated from fossil resources. We also argue that a scientific understanding of net zero provides a basis for assigning responsibility for the protection of passive carbon sinks during and after the transition to geological net zero. (Myles R. Allen, David J. Frame, Kirsten Zickfeld , more at nature.com)