IPCC AR5

IPCC AR5
Name	Fifth Assessment Report
Abbreviation	AR5
Author	Intergovernmental Panel on Climate Change
Released	2013–2014
Components	Working Group I, Working Group II, Working Group III, Synthesis Report
Language	English
Subject	Climate change

IPCC AR5 The Fifth Assessment Report (2013–2014) of the Intergovernmental Panel on Climate Change synthesized peer-reviewed literature on atmospheric science, impacts, and mitigation. Commissioned and coordinated by Intergovernmental Panel on Climate Change, it involved hundreds of authors drawn from institutions such as National Aeronautics and Space Administration, National Oceanic and Atmospheric Administration, Met Office Hadley Centre, and Lawrence Berkeley National Laboratory. The report informed negotiations under the United Nations Framework Convention on Climate Change and influenced national policy debates in forums like the United Nations General Assembly and the G20 summit.

Overview

AR5 provided a consolidated assessment across physical science, impacts and vulnerability, and mitigation, culminating in a Synthesis Report that fed into diplomatic processes including the Paris Agreement negotiations. Lead authors represented academic centres such as University of Oxford, Massachusetts Institute of Technology, University of Cambridge, Columbia University, and Potsdam Institute for Climate Impact Research. The timeline spanned assessment cycles that followed earlier reports like the First Assessment Report and Fourth Assessment Report, reflecting advances in climate modelling from groups including IPSL-CM5, HadGEM2-ES, and GFDL CM3.

Assessment Reports and Working Groups

AR5 comprised three Working Group reports and a Synthesis Report. Working Group I addressed physical science and drew on contributions from observational programs such as Global Climate Observing System and satellite missions like GRACE and Aqua (satellite). Working Group II assessed impacts, adaptation, and vulnerability with case studies referencing regions including Small Island Developing States, the Arctic, and the Mediterranean Basin. Working Group III evaluated mitigation pathways, economic models, and technologies involving actors like Inter-American Development Bank and firms in the renewable energy sector. The Synthesis Report integrated findings for policymakers and linked to processes under United Nations Framework Convention on Climate Change.

Key Findings and Conclusions

AR5 concluded with high confidence that human influence on the climate system is clear, citing indicators from observed surface warming, diminishing snow and ice, and sea level rise recorded by ICESat and tide gauges. Projections used Representative Concentration Pathways developed alongside modelling centres such as MPI-ESM and MRI-CGCM3. The report quantified climate sensitivity ranges discussed in the climate literature connected to researchers at Scripps Institution of Oceanography and National Center for Atmospheric Research. AR5 explicitly updated assessments of extreme events, carbon cycle feedbacks studied by groups like Carnegie Institution for Science, and permafrost carbon stocks relevant to International Arctic Research Center.

Methodology and Models

AR5 employed multi-model ensembles from the Coupled Model Intercomparison Project Phase 5 and used detection and attribution methods refined in studies from Hadley Centre, NOAA Geophysical Fluid Dynamics Laboratory, and CSIRO. The report relied on observational syntheses from programmes including Global Precipitation Climatology Project and paleoclimate reconstructions involving teams at Lamont–Doherty Earth Observatory and University of Bern. Statistical techniques cited work by scholars affiliated with Princeton University and ETH Zurich; scenario analysis used integrated assessment models produced by groups such as MESSAGE, REMIND, and IMAGE.

Impacts, Risks, and Adaptation

Working Group II documented risks to sectors and regions, with examples drawn from studies in Bangladesh, Brazil, Australia, Sub-Saharan Africa, and European Union member states. AR5 evaluated ecosystem responses described in literature from World Wildlife Fund collaborations and coral reef studies from Australian Institute of Marine Science. Adaptation options referenced international funding mechanisms like the Green Climate Fund and technical measures examined by World Bank reports. The report stressed vulnerability in Least Developed Countries and highlighted cross-cutting issues addressed in assessments by International Union for Conservation of Nature.

Mitigation Strategies and Policy Implications

Working Group III explored emission pathways, carbon pricing instruments examined by European Commission and World Bank, and technology portfolios including deployment of solar photovoltaic systems tracked by International Renewable Energy Agency and carbon capture approaches researched at Energy Technologies Institute. Scenarios consistent with limiting warming drew on analyses by International Energy Agency and academic modelling teams at Stanford University and Tsinghua University. AR5 informed policy design in national contributions submitted to United Nations Framework Convention on Climate Change processes and underpinned consultation by finance ministries and central banks such as Bank of England.

Reception, Criticism, and Influence on Policy

AR5 received broad endorsement from scientific bodies including the Royal Society, U.S. National Academy of Sciences, and European Commission. Critics from think tanks and commentators associated with institutions such as Heritage Foundation engaged debates on uncertainty and policy costs, while some research groups questioned specific model projections and sea level estimates in journals like Nature and Science. Policymakers referenced AR5 in formulating the Paris Agreement commitments and national climate plans filed under United Nations Framework Convention on Climate Change, and the report shaped public discourse covered by outlets including BBC News, The New York Times, and The Guardian.

Category:Intergovernmental Panel on Climate Change reports