Climate science struggles to explain hot world
Although there are indications that the global temperature might be starting to drop – July was the first month on over a year that did not set a record – climate scientists are still at a loss to explain why 2023 and 2024 so far has been so hot. Individual causes have been examined; El Nino, fewer aerosols, the Hunga-Tonga explosion, solar influence, but they collectively cannot provide an explanation. It is estimated that 0.2 deg C of warming is unattributed, a factor that is well outside any prediction of the CMIP6 climate models. Scientists will gather later this year at the AGU meeting to attempt to make sense of what has been happening.
The latest global temperature data – HadCRUT5 – from the UK’s Met Office shows just how peculiar the past year or so has been. The figure shows HadCRUT5 for this century as 24 years of data is a not insignificant proportion of the canonical 30-year climate definition. Note the errors are of the order of 0.1°C.
Firstly, the global temperature hiatus of 2001–2014 is clearly seen. It represent more than a decade of no global warming in this dataset. It was terminated by the build-up to an intense El Niño, but when that subsided in 2016 another, shorter, standstill occurred until interrupted by the recent abnormal warm spell. During the 2016–2023 period, the El Niños could be interpreted as perturbations that returned to the new level afterwards…until 2023.
Another observation that emerges from this data is that during this century, the majority of years saw no increase in temperature over the previous year!
What has happened since 2023 is like nothing else seen in the past quarter century; a single event stronger and longer than anything else. The pertinent question is, of course, what will happen now, as global temperatures start to fall. Will a new level be established, as it was after the 2015 El Niño or will it return to the post-2015 temperature? Given that the models are inadequate to predict
A final point is that there has been some discussion of an acceleration in global warming as a result of the unusual warmth of 2023 - 2024. Clearly this is premature until we better understand the reasons behind the temperature anomaly of 2023–2024. Perhaps by the AGU meeting in December we might be closer to an understanding? What is clear right now is that nature has shown us we don’t understand what is going to our climate as well as we thought we did. Why is this a surprise?