Uh-oh: Michael Mann holds up James Hansen's handling of Pinatubo as an example of allegedly successful climate modeling; however, while Hansen said the Pinatubo cooling would last "several years", Hansen was still blaming Pinatubo for lack of warming *20* years later

How Do We Know Humans are Responsible for Global Warming? | Earth Day 2013 | Weather Underground

[Michael Mann] The key question is, can the model be shown to be useful? Can it make successful predictions?

Climate models had passed that test with flying colors by the mid-1990s. James Hansen, in the late 1980s, successfully predicted the continuing warming that would be observed by the mid-1990s. Even something the model couldn't have predicted in advance—the 1991 eruption of Mount Pinatubo in the Philippines—provided yet another key test. As soon as the eruption occurred, Hansen put what was known about the reflective qualities of volcanic sulfur particulates (known as sulfate "aerosols") into the simulations. The aerosols cooled surface temperatures for several years in the model by shielding the surface from a fraction of incoming sunlight, leading Hansen to make what turned out to be a successful prediction of the temporary cooling that was seen over the ensuing few years.

2011: In an attempt to explain the lack of ocean warming, Jim Hansen blames the sun and the 1991 Mount Pinatubo eruption

We conclude that recent slowdown of ocean heat uptake was caused by a delayed rebound effect from Mount Pinatubo aerosols and a deep prolonged solar minimum.