  Earlier meta-analyses of the economic impact of climate change are updated
with more data, with three new results: (1) The central estimate of the
economic impact of global warming is always negative. (2) The confidence
interval about the estimates is much wider. (3) Elicitation methods are most
pessimistic, econometric studies most optimistic. Two previous results remain:
(4) The uncertainty about the impact is skewed towards negative surprises. (5)
Poorer countries are much more vulnerable than richer ones. A meta-analysis of
the impact of weather shocks reveals that studies, which relate economic growth
to temperature levels, cannot agree on the sign of the impact whereas studies,
which make economic growth a function of temperature change do agree on the
sign but differ an order of magnitude in effect size. The former studies posit
that climate change has a permanent effect on economic growth, the latter that
the effect is transient. The impact on economic growth implied by studies of
the impact of climate change is close to the growth impact estimated as a
function of weather shocks. The social cost of carbon shows a similar pattern
to the total impact estimates, but with more emphasis on the impacts of
moderate warming in the near and medium term.
