Last updated September 29, 2021

IPCC AR5 WGI: Climate Change 2013: The Physical Science Basis

The Working Group I contribution to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change:

  • Finds that warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia
  • Finds that the atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased
  • Finds each of the last three decades has been successively warmer at the Earth’s surface than any preceding decade since 1850
  • 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
  • Builds upon the Working Group I contribution to the IPCC’s Fourth Assessment Report (AR4), and incorporates subsequent new findings of research
  • Provides an important basis for information on changing weather and climate extremes