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

ACP - Abstract - Earth's energy imbalance and implications

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. Observed sea level rise during the Argo float era is readily accounted for by ice melt and ocean thermal
expansion, but the ascendency of ice melt leads us to anticipate acceleration of the rate of sea level rise this decade.

Mount Pinatubo Eruption - Eruption of Mount Pinatubo

In June 1991, the second largest volcanic eruption of the twentieth century* took place on the island of Luzon in the Philippines, a mere 90 kilometers (55 miles) northwest of the capital city Manila.