More and more people are realizing: Even if we reach net zero by 2050, or stay “well under” 2°C of warming, our survival will still be in serious doubt.  That’s because there are already a trillion tons of CO2 in the atmosphere. This “legacy” CO2, emitted over the last 200 years, will continue to wreak havoc in our world—whether or not we decrease future emissions to near-zero.