title: Large differences in regional precipitation change between a first and second 2 K of global warming.
abstract: For adaptation and mitigation planning, stakeholders need reliable information about regional precipitation changes under different emissions scenarios and for different time periods. A significant amount of current planning effort assumes that each K of global warming produces roughly the same regional climate change. Here using 25 climate models, we compare precipitation responses with three 2 K intervals of global ensemble mean warming: a fast and a slower route to a first 2 K above pre-industrial levels, and the end-of-century difference between high-emission and mitigation scenarios. We show that, although the two routes to a first 2 K give very similar precipitation changes, a second 2 K produces quite a different response. In particular, the balance of physical mechanisms responsible for climate model uncertainty is different for a first and a second 2 K of warming. The results are consistent with a significant influence from nonlinear physical mechanisms, but aerosol and land-use effects may be important regionally.
authors.affiliation: Met Office Hadley Centre, Exeter EX1 3PB, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Good
authors.affiliation: Met Office Hadley Centre, Exeter EX1 3PB, UK.
authors.forename: Ben B B
authors.initials: BB
authors.lastname: Booth
authors.affiliation: Met Office Hadley Centre, Exeter EX1 3PB, UK.
authors.forename: Robin
authors.initials: R
authors.lastname: Chadwick
authors.affiliation: NCAS-Climate, University of Reading, Reading RG6 6BB, UK.
authors.forename: Ed
authors.identifier: 0000-0001-9477-3677
authors.initials: E
authors.lastname: Hawkins
authors.affiliation: Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Jonko
authors.affiliation: Met Office Hadley Centre, Exeter EX1 3PB, UK.
authors.forename: Jason A
authors.initials: JA
authors.lastname: Lowe