There has been a lot of commentary about perceived disagreements among climate scientists about whether climate change is, or will soon, accelerate. As with most punditry, there is less here than it might seem. Last year, Jim Hansen and colleagues published a long paper that included a figure suggesting that they expected that global temperature trends from 2011 to increase above the recent linear trends. Fig. 24 from Hansen et al (2023). This has meshed with another argument around whether an acceleration of global temperatures in recent decades can already be detected. Tamino has made a cas ..read more

This month’s open thread on climate topics. Lots more discussion about 2023, aerosols, heat content and imbalances to come I expect… Note, comments should be substantive even if you are arguing with who you perceive to be the worst person in the world. Comments that are mainly personal attacks will just get deleted. The post Unforced variations: Apr 2024 first appeared on RealClimate ..read more

Going back a few months, I spent a bit of time pointing out the strategy and nonsense in the various Willie Soon and company’s efforts to blame current warming on solar activity. I specifically pointed out their cultish devotion to a single solar activity reconstruction (Hoyt and Schatten, 1993) (HS93); with an update from Scaffeta (2023), and their increasingly elaborate efforts to create temperature series that correlate to it. Well, Theodosios Chatzistergos has just published a deep dive into the HS93 reconstruction (Chatzistergos, 2024) (C24) and… let’s say the results will not be surpris ..read more

The month’s open thread on climate topics. More record monthly warmth, but only the second lowest Antarctic sea ice though (growing since 2023!). The post Unforced variations: March 2024 first appeared on RealClimate ..read more

A new paper was published in Science Advances today. Its title says what it is about: “Physics-based early warning signal shows that AMOC is on tipping course.” The study follows one by Danish colleagues which made headlines last July, likewise looking for early warning signals for approaching an AMOC tipping point (we discussed it here), but using rather different data and methods. The new study by van Westen et al. is a major advance in AMOC stability science, coming from what I consider the world’s leading research hub for AMOC stability studies, in Utrecht/Holland. (Some of their contribu ..read more

This month’s open thread for climate topics. This month’s climate highlight will likely be the PACE launch at some point between Feb 6th and Feb 8th, that will hopefully provide information on aerosols and ocean color with more detail than ever before. Fingers crossed! A few notes on the blog and commenting. We have an open thread (this one!) for random discussions or new topics. Comments on specific posts should be related to the topic. Random contrarian nonsense is just going to get deleted (as are the complaints about it). Additionally, excessive and argumentative commenting is tiresome ..read more

A recent sensible-sounding piece by Roy Spencer for the Heritage foundation is full of misrepresentations. Let’s play spot the fallacy. Comparing climate models to observations is usually a great idea, but there are some obvious pitfalls to avoid if you want to be taken seriously. The most obvious one is to neglect the impacts of internal variability – which is not synchronized across the models or with the observations. The second is to avoid cherry picking your comparison – there is always a spread of results by just looking at one small region, in one season, in one metric, so it’s pretty ..read more

Annual updates to the model-observation comparisons for 2023 are now complete. The comparisons encompass surface air temperatures, mid-troposphere temperatures (global and tropical, and ‘corrected’), sea surface temperatures, and stratospheric temperatures. In almost every case, the addition of the 2023 numbers was in line with the long term expectation from the models. There were a few minor changes this year: Old versions of the NOAA STAR TMT data are no longer available and so they’ve been removed. All NOAA NCEI surface temperature lines are now using v5.1. New comparisons for SST and TMT ..read more

As the climate monitoring groups add an additional dot to their graphs this week, there is some disquiet among people paying attention about just how extraordinary 2023 really was. First, it’s been obvious for months that 2023 would be a record year – in temperatures (at the surface, troposphere and in the ocean), in Antarctic sea ice, in the number of big climate disasters etc. But this was not at all obvious at the beginning of the year – even assuming that El Niño would develop by the this winter. Indeed, even as late as October, with only two months to go, the estimates for the annual mea ..read more

For the last few years (since at least 2016), I’ve shared predictions for the next annual global mean surface air temperature (GMSAT) anomaly based on the long term trend and the state of ENSO at the start of the year. Generally speaking, this has been quite skillful compared to persistence or just the long term trend alone – the eventual anomaly was consistently within the predicted bounds. Until 2023. As described in my original post on 538, I take a loess smooth for the GISTEMP long term trend (using roughly 20 year smoothing) and add a term based on the linear regression of the beginning ..read more