IPCC fifth assessment report: climate change 2013 - The physical science basis (IPCC WGI AR5)

This document presents the Working Group I (WGI) contribution to the IPCC Fifth Assessment Report (AR5). It provides a comprehensive assessment of the physical science basis of climate change in 14 chapters, supported by a number of annexes and supplementary material. The document considers new evidence of climate change based on many independent scientific analyses from observations of the climate system, paleoclimate archives, theoretical studies of climate processes and simulations using climate models.

Among the projections of changes in the climate system, it includes: (i) larger projections of sea level rise than in the AR4, primarily because of improved modelling of land-ice contributions; (ii) global mean temperatures increase resulting in a higher frequency and duration of heat waves and occasional cold winter extremes occurrences over most land areas on daily and seasonal timescales; (iii) more intense and more frequent extreme precipitation events over most of the mid-latitude land masses and over wet tropical regions; and (iv) El Niño-Southern Oscillation (ENSO) remaining the dominant mode of interannual variability in the tropical Pacific.

The report builds upon the Working Group I contribution to the IPCC’s Fourth Assessment Report (AR4), and incorporates subsequent new findings of research. As a component of the fifth assessment cycle, the IPCC Special Report on Managing the Risks of Extreme Events to Advance Climate Change Adapt ation (SREX) is an important basis for information on changing weather and climate extremes.