How IPCC’s 1990 Predictions Expensively Failed

by C. Monckton of Brenchley, Nov 8, 2022 in WUWT

It is now almost a third of a century since 1990, when IPCC made its first predictions about the weather. Since IPCC (2021) continues to predict the same 3 C° midrange long-term warming (equilibrium doubled-CO2 sensitivity, or ECS, broadly equivalent to 20th-century anthropogenic warming from all sources) as in 1990, it is high time someone examined IPCC’s medium-term predictions to shed light on the plausibility of its long-term predictions.

IPCC’s key medium-term prediction in 1990 was as follows –

“Based on current model results, we predict:

  • “under the IPCC Business-as-Usual (Scenario A) emissions of greenhouse gases, a rate of increase of global mean temperature during the next century of about 0.3 C° per decade (with an uncertainty range of 0.2 C° to 0.5 C° per decade). This is greater than that seen over the past 10,000 years. This will result in a likely increase in global mean temperature of about 1 C° above the present value by 2025 and 3 C° before the end of the next century. The rise will not be steady because of the influence of other factors.”

IPCC also predicted as follows –

This second business-as-usual prediction was that there would be 1.8 C° warming from preindustrial times to 2030. Deducting the 0.45 C° warming up to 1990, the prediction amounted to 1.35 C° or about 0.34 C°/decade. Thus, IPCC predicted 0.3-0.34 C°/decade medium-term warming. However, only 0.14 C°/decade has occurred since 1990