Amicus Curiae Brief presented by ClientEarth 21 November 2016 been the dominant cause of the observed warming since the mid-20th century."64 [Emphasis in original]. 81. The detection and attribution report (Chapter 10) states that: "[m]ore than half of the observed increase in global mean surface temperature (GMST) from 1951 to 2010 is very likely due to the observed anthropogenic increase in greenhouse gas (GHG) concentrations. The consistency of observed and modeled changes across the climate system, including warming of the atmosphere and ocean, sea level rise, ocean acidification and changes in the water cycle, the cryosphere and climate extremes points to a large-scale warming resulting primarily from anthropogenic increases in GHG concentrations. Solar forcing is the only known natural forcing acting to warm the climate over this period but it has increased much less than GHG forcing, and the observed pattern of long-term tropospheric warming and stratospheric cooling is not consistent with the expected response to solar irradiance variations. The Atlantic Multi-decadal Oscillation (AMO) could be a confounding influence but studies that find a significant role for the AMO show that this does not project strongly onto 1951–2010 temperature trends." 65 [Emphasis Added] 82. As previously explained, ‘very likely’ is used by the IPCC to indicate that a result is 90–100% certain in terms of scientific proof, indicating a clear and rigorously proven causal relationship between two physical phenomena. 66 This indicates that the 64 IPCC AR5, Synthesis Report, Summary for Policymakers. See note 46 at p 4. IPCC AR5, Synthesis Report, Summary for Policymakers. See note 46 at p 869. 66 IPCC, Guidance Note for Lead Authors of the IPCC Fifth Assessment Report on 65 41