Predicted Chance That Global Warming Will Temporarily Exceed 1.5 °C
Observations of global mean temperature contain both externally-forced temperature change and superimposed natural variability. Natural variability may temporarily add to the underlying externally-forced warming, leading to observed temperatures that are higher than 1.5 °C for short-term periods. Here we develop a new capability to predict the likelihood that global temperature will exceed 1.5 °C above preindustrial levels in the coming 5 years. We use decadal climate predictions that are regularly produced by several international climate prediction centers. Importantly, these predictions take into account the observed present-day conditions since this is essential to predict the evolution of natural variability. For the period 2017 to 2021 we predict a 38% and 10% chance, respectively, of monthly or yearly temperatures exceeding 1.5 °C, with virtually no chance of the 5-year mean being above the threshold.