Integrating tipping points into climate impact assessments

There is currently a huge gulf between natural scientists’ understanding of climate tipping points and economists’ representations of climate catastrophes in integrated assessment models (IAMs). In particular, there are multiple potential tipping points and they are not all low-probability events; at least one has a significant probability of being passed this century under mid-range (2–4 °C) global warming, and they cannot all be ruled out at low (>2 °C) warming. In contrast, the dominant framing of climate catastrophes in IAMs, and in critiques of them, is that they are associated with high (> 4 °C) or very high (> 8 °C) global warming. This discrepancy could qualitatively alter the predictions of IAMs, including estimates of the social cost of carbon. To address this discrepancy and assess the economic impact of crossing different climate tipping points, we highlight a list of scientific points that should be considered, at least in a stylised form, in simplified IAMs. For nine different tipping events, the range of expected physical climate impacts is summarised and some suggestions are made for how they may translate into socio-economic impacts on particular sectors or regions. We also consider how passing climate tipping points could affect economic growth. Copyright Springer Science+Business Media B.V. 2013