New study suggests the Atlantic overturning circulation AMOC “is on tipping course”
RealClimate
by Stefan
2w ago
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
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Unforced variations: Feb 2024
RealClimate
by group
3w ago
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
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Spencer’s Shenanigans
RealClimate
by Gavin
3w ago
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
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Not just another dot on the graph? Part II
RealClimate
by Gavin
1M ago
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
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Not just another dot on the graph?
RealClimate
by Gavin
1M ago
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
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Annual GMSAT predictions and ENSO
RealClimate
by Gavin
1M ago
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
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Unforced variations: Jan 2024
RealClimate
by group
1M ago
New year, new open thread on climate topics. Note that summaries and updates to include 2023 data will be posted on the surface temperature graphics page and model-observations comparison page over the next couple of weeks as the data becomes available. The post Unforced variations: Jan 2024 first appeared on RealClimate ..read more
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2023 appears to follow an upward trend in the North Atlantic/Caribbean named tropical cyclone count
RealClimate
by rasmus
2M ago
This year’s (2023) tropical cyclone season in the North Atlantic and Caribbean witnessed a relatively high number of named tropical cyclones: 20. In spite of the current El Niño, which tends to give lower numbers. But it appears to follow a historical trend for named tropical cyclones with an increasing number over time. The number of North Atlantic/Caribbean named tropical cyclones in and the estimates based on the area with sea surface temperature above 25.6°C (Benestad, 2009). The curve presented above is an update of the analysis presented in 2020 and posted here on RealClimate. The relat ..read more
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Unforced Variations: Dec 2023
RealClimate
by group
2M ago
Well, that year went quickly. This month, there is the COP28 hoopla, the ongoing El Niño and the speculation about the 2023 temperature ranking (which will not be that surprising). An open thread for climate topics… The post Unforced Variations: Dec 2023 first appeared on RealClimate ..read more
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Science denial is still an issue ahead of COP28
RealClimate
by Stefan
3M ago
It is 33 years now since the IPCC in its first report in 1990 concluded that it is “certain” that greenhouse gas emissions from human activities “will enhance the greenhouse effect, resulting on average in an additional warming of the Earth’s surface.” That has indeed happened as predicted, it has been confirmed by a zillion studies and has been scientific consensus for decades. Yet, when the next global climate summit is coming up (it’s starting tomorrow), we don’t only learn that the host, United Arab Emirates, intends to use the event for new oil deals. We also see more attempts to cast do ..read more
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