I did basic undergrad research in class on this back in 2009: We didn’t have a way to suddenly stop burning fossil fuels other than a mass extinction of humans. We can undo the damage if we want to, but halting what is already happening requires creating butanol from renewable sources and pumping it underground. Other methods of “Suddenly dump a truckload of cash on researching a solution” required a shitload of carbon emissions until we got to the point of “maybe we are carbon zero”