IPCC First Assessment Report

The First Assessment Report (FAR) of the <a href="/facts/Intergovernmental_Panel_on_Climate_Change/sh76du1u">Intergovernmental Panel on Climate Change</a> (IPCC) was completed in 1990. It served as the basis of the <a href="/facts/United_Nations_Framework_Convention_on_Climate_Change/Tg7f18g3">United Nations Framework Convention on Climate Change</a> (UNFCCC). This report had effects not only on the establishment of the UNFCCC, but also on the first session of the Conference of the Parties (COP), held in Berlin in 1995. The executive summary of the WG I Summary for Policymakers report that said they were certain that emissions resulting from human activities are substantially increasing the <a href="/facts/Carbon_dioxide_in_Earth%2527s_atmosphere/h6A4HSzy">atmospheric concentrations of the greenhouse gases</a>, resulting on average in an additional warming of the <a href="/facts/Earth/HLLmDfj0">Earth</a>'s surface. They calculated with confidence that CO2 had been responsible for over half the enhanced <a href="/facts/Greenhouse_effect/LGdNYYj3">greenhouse effect</a>.
They predicted that under a "business as usual" (BAU) scenario, global mean temperature would increase by about 0.3 °C per decade during the [21st] century. They judged that global mean surface air temperature had increased by 0.3 to 0.6 °C over the last 100 years, broadly consistent with prediction of climate models, but also of the same magnitude as natural climate variability. The unequivocal detection of the enhanced greenhouse effect was not likely for a decade or more.
The 1992 supplementary report was an update, requested in the context of the negotiations on the UNFCCC at the <a href="/facts/Earth_Summit/m43Ql7gs">Earth Summit</a> (United Nations Conference on Environment and Development) in <a href="/facts/Rio_de_Janeiro/AVPTJJ2C">Rio de Janeiro</a> in 1992. The major conclusion was that research since 1990 did "not affect our fundamental understanding of the science of the greenhouse effect and either confirm or do not justify alteration of the major conclusions of the first IPCC scientific assessment". It noted that transient (time-dependent) simulations, which had been very preliminary in the FAR, were now improved, but did not include aerosol or ozone changes.

IPCC First Assessment Report open-in-new

IPCC First Assessment Report