Climate model limitations tend to overestimate climate change attribution

The influence of climate change on extreme weather and climate events is topical in climate science. Recent extreme events (such as the European heatwave in 2015 [1]) have been partly attributed to climate change by comparing the probability that the event would occur in the world as we observe it with the probability that it would occur in a hypothetical world where climate change does not exist. These probabilities are typically estimated using climate model simulations with known limitations to simulate extreme events. A study published today in Geophysical Research Letters suggests that there is a tendency to overestimate the attribution as a result of the shortcomings of these models.

Climate models are the best tools we have to perform an event attribution study, yet the models have known imperfections with respect to reliably simulating the probability that an event might occur. The authors of the study point out that model reliability is not always ensured and that past studies have paid too little attention to this requirement. Attribution studies would therefore benefit from ensemble calibration methods conducted by today’s operational weather and climate forecasting centres. However, the authors also stress that, while there is a risk that its influence has been overestimated, climate change has been an important factor in the development of recent extreme events.

You can read the full article “Attribution of extreme weather and climate events overestimated by unreliable climate simulations” in:http://onlinelibrary.wiley.com/doi/10.1002/2015GL067189/abstract