Forecasting Climate Change using a Multivariate Cointegrated System

A cointegrated vector equilibrium correction model of key climate variables — including sea surface temperature, ocean heat content, Arctic sea-ice extent and sea-level change — is developed, driven by radiative forcing in which a stochastic trend arises due to anthropogenic greenhouse gas emissions. A valid and congruent statistical model requires saturation estimation to model breaks in trends, while also conditioning on natural radiative forcings and the El Niño–Southern Oscillation. The model is stable over 150 years, reflecting the slow adjustment of the deep oceans to increased greenhouse gas concentrations, and predicts an equilibrium climate sensitivity of 2.6°C. Projections to 2100 highlight the substantial uncertainties over the coming decades.