Human influence on climate system is clear, says IPCC summary

Major update: On 30 September 2013 the IPCC released the Final Draft Report of the Working Group I contribution to the IPCC Fifth Assessment Report Climate Change 2013. This is commonly called ‘The Physical Science Basis’. It consists of the full scientific and technical assessment undertaken by Working Group I.

The Final Draft consists of 19 documents – 14 chapters, three annexes, a technical summary and a changes summary. These you will find via this list:

01 Technical Summary (6.05 MB)
02 Ch01 Introduction (2.66 MB)
03 Ch02 Observations: Atmosphere and Surface (10.40 MB)
04 Ch03 Observations: Ocean (18.10 MB)
05 Ch04 Observations: Cryosphere (5.18 MB)
06 Ch05 Information from Paleoclimate Archives (4.78 MB)
07 Ch06 Carbon and Other Biogeochemical Cycles (8.90 MB)
08 Ch07 Clouds and Aerosols (3.48 MB)
09 Ch08 Anthropogenic and Natural Radiative Forcing (2.83 MB)
10 Ch09 Evaluation of Climate Models (6.81 MB)
11 Ch10 Detection and Attribution of Climate Change: from Global to Regional (4.39 MB)
12 Ch11 Near-term Climate Change: Projections and Predictability (5.45 MB)
13 Ch12 Long-term Climate Change: Projections, Commitments and Irreversibility (25.50 MB)
14 Ch13 Sea Level Change (6.17 MB)
15 Ch14 Climate Phenomena and their Relevance for Future Regional Climate Change (7.74 MB)
16 Annex I: Atlas of Global and Regional Climate Projections (36.50 MB)
17 Annex II: Glossary (0.80 MB)
18 Annex III: Acronyms and Regional Abbreviations (0.50 MB)
19 Changes to the Underlying Scientific/Technical Assessment (0.20 MB)

Map of the observed surface temperature change from 1901 to 2012 derived from temperature trends. The globally averaged combined land and ocean surface temperature data as calculated by a linear trend, show a warming of 0.85 [0.65 to 1.06] °C, over the period 1880–2012. For the longest period when calculation of regional trends is sufficiently complete (1901–2012), almost the entire globe has experienced surface warming. Source: IPCC

Early statements and releases from the Twelfth Session of Working Group I which was held from 2013 September 23-26 in Stockholm, Sweden. The press release about the human influence on the climate system is here, which has said “this is evident in most regions of the globe”.

The IPCC has also provided headline statements from the Summary for Policymakers of the Working Group contribution to AR5. At the Session, the Summary for Policymakers (SPM) of the Working Group I contribution to the IPCC Fifth Assessment Report (WGI AR5) was approved and the underlying scientific and technical assessment accepted. (See the earlier post on the AR5 process.)

For the Fifth Assessment Report, the scientific community has defined a set of four new scenarios. These are called Representative Concentration Pathways (RCPs). These four RCPs include one ‘mitigation scenario’ leading to a very low radiative forcing level (RCP2.6). (Radiative forcing is the change in net irradiance; it is used to assess and compare the anthropogenic and natural drivers of climate change). There are two ‘stabilisation scenarios’ (RCP4.5 and RCP6), and one scenario with very high greenhouse gas emissions (RCP8.5). The RCPs can thus represent a range of 21st century climate policies.