As we saw in Sect. 2.2 , the amount of future global warming in the twenty-first century will essentially depend on the magnitude of future anthropogenic greenhouse gas emissions, which, in turn, will depend on how human society develops and changes. However, it is important to emphasize that it is not only the amount of subsequent anthropogenic emissions that will determine how warm our future climate will be. Even if human-induced greenhouse gas emissions are substantially reduced (even if to zero, hypothetically) global temperatures will still continue to rise. The reason is that further global warming will also depend on a largely underestimated factor known as “positive climate feedbacks” which are natural processes triggered by global warming resulting from increased concentrations of greenhouse gases in the atmosphere, and which significantly amplify this warming.