Climate forcing by the volcanic eruption of Mount Pinatubo

We determine the volcano climate sensitivity λ and response time τ for the Mount Pinatubo eruption, using observational measurements of the temperature anomalies of the lower troposphere, measurements of the long wave outgoing radiation, and the aerosol optical density. Using standard linear response theory we find λ = 0.15 ± 0.06 K/(W/m 2 ), which implies a negative feedback of −1.4 (+0.7, −1.6). The intrinsic response time is τ = 6.8 ± 1.5 months. Both results are contrary to a paradigm that involves long response times and positive feedback.