When we emit CO₂, it hangs around in the atmosphere for about 1000 years. There is already too much CO₂ in the air for a tolerable degree of climate change. Even what we have emitted already will continue making the earth hotter and ever hotter for centuries to come. Thus we can’t talk about safe levels of emissions. Even zero is too much. We have to start removing the atmospheric CO₂ that we have already emitted.
~ Roedy (born: 1948-02-04 age: 61)