Parry et al. reply

David Fisk is correct in drawing attention to our interpretation of the Kyoto Protocol. Because the protocol sets targets only through to 2008-2012, we assumed that emissions would be constant thereafter, but only as a starting point for our analysis. We recognize, and indeed hope, that further reductions in emissions beyond 2012 will be agreed under the protocol, and we gave estimates of impacts following substantially greater reductions.

Contrary to what Fisk states, our argument about the necessity for adaptation remains intact. Indeed, under two more progressive assumptions about post-2012 emissions targets, global warming by 2050 — and the associated impacts — will still be substantial (Table 1). The assumption of continued reductions in 38 industrialized ‘annex I’ countries, and the involvement of non-annex I nations by 2020, reduces warming by the year 2050 by only 0.15 °C. Such post-2012 commitments will of course yield larger benefits in the longer term, but the inertia in the carbon cycle and climate system means that we will need to ‘adapt to the inevitable’ in the medium term.

Table 1 Estimates of global warming for the year 2050
Full size table