27 March 2019

Predicted Chance That Global Warming Will Temporarily Exceed 1.5 °C

Science

  

Impact

  

Summary

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.

Contact
Gerald Meehl
National Center for Atmospheric Research (NCAR)
Publications
Smith, D, A Scaife, E Hawkins, R Bilbao, G Boer, M Caian, L Caron, et al.  2019.  "Predicted Chance That Global Warming Will Temporarily Exceed 1.5 °C."  Geophysical Research Letters 45(21): 11895-11903.  https://doi.org/10.1029/2018gl079362.