Out now in @Nature: @KenCaldeira and I show that Earth’s recent energy budget suggests greater future global warming than raw climate model projections indicate.
patricktbrown.org/2017/11/29/gre…
patricktbrown.org/2017/11/29/gre…
Key takeaway 1) Climate models that simulate the recent past the best, tend to simulate above average warming in the future. This is mostly due to ‘better’ models simulating more-positive shortwave cloud feedbacks.
Key takeaway 2) Our projections that combine information from observations with climate model output suggest 10-20% more warming than projections based on climate models alone.
Key takeaway 3) Our projections show a substantial decrease in the likelihood of low-end (less severe) warming projections.
Key takeaway 4) Our best estimate for 21st-century warming under RCP 4.5 is about the same as the previous best estimate for RCP 6.0. So if we decarbonize along the RCP 4.5 pathway, we should expect global temperatures to follow the trajectory previously associated with RCP 6.0.
Key takeaway 5) Some think that severe warming projections can be dismissed since models are imperfect. Our study confirms ample room for model improvement but we show that model shortcomings can likely be used to dismiss the least (not the most) severe warming projections.
