The Atmospheric Physics Behind Net Zero

Before net zero, climate policy was all about contraction and convergence of emissions between rich and poor to achieve, in the words of the Rio Convention, “stabilization of greenhouse gas concentrations in the atmosphere” at a safe level. But scientists struggled to establish what that “safe” level was, making little progress in over a quarter of a century. And it was not because we were incompetent: for fundamental reasons in physics and probability theory, we were asking the wrong questio...