2023 is trending to be the hottest year on record.
As the creator is inactive I say that if conflict between datasets arise NASA will be leading.
Just preventing a possible discussion in a year.
The mystery is why last year’s fall was so unbelievably hot because it doesn’t seem like you can reasonably attribute much of that to el nino.
my speculation is that reducing shipping emissions likely has the greatest warming effects on world temps in/around Aug/Sept (the time of year when northern hemisphere oceans-which have seen the greatest reduction in sulfur pollution-are retaining the most excess energy from the sun).
You see that effect in Aug/September North Atlantic surface temps ever since ships have reduced emissions (2020 to today). https://climatereanalyzer.org/clim/sst_daily/
Sketchy: There is a delay from El Nino to the peak heating effect from El Nino. (Also we haven't reached fall 2024 yet.)
Will: If shipping emissions are reducing sulfur which is a cooling effect, should this warm year round temperatures equally or maybe warm winter temperatures most? Or are you suggesting shipping is seasonal and had more emissions in summer? Edit Probably talking rubbish here. Greatest cooling effect where northern hemisphere insolation is greatest because people and therefore shipping mainly in NH.
I would have expected a 2-3 year build up in effects to initially be more pronounced than seasonal effects but I could easily be completely wrong.
There is a delay from El Nino to the peak heating effect from El Nino. (Also we haven't reached fall 2024 yet.)
@ChristopherRandles I'm not sure I get what you mean here. El Nino doesn't end all at once, but we're still just as hot as last year despite its influence waning. And yea we're not in fall yet, that's sort of why I said "turning into". If temps dip in the next month or so there's not too much mystery, it's just a slightly unexpectedly hot summer.
ONI and other ENSO measures may have passed +0.5 around June 2023 and reached peak around December 2023. The effect we would expect this to have on global average temperature would normally be for the temperature to start rising somewhere around August 2023 and not reach its peak until February 2024.
The exact length of this delay is hard to pin down. 2 months might be a reasonable rough single figure but you get a better fit for global temperature looking at average ONI over longer range periods like 1 to 6 months previously.
Regarding the really hot September 2023, while El Nino had started, the El Nino doesn't really explain much of those warm temperatures because the temperature effect should barely be starting.
ONI may have ceased to be over 0.5 in May 2024 but the lingering temperature effect can still at least to some extent explain hot July 2024 temperatures.
So I am agreeing with Will that the mystery is still the hot fall 2023 much more than the hot July 2024.
Of course if the high temperatures continue, then it could become the fall 2024 temperatures that 'rapidly become' more of a mystery. However we haven't got there yet.
Yes, since shipping is mostly north hemisphere, reducing aerosols would cause biggest heating effect in northern hemisphere late spring to early summer--when those aerosols would otherwise be blocking the most amount of sunlight. I'd expect the biggest cumulative global temperature increase would be whenever northern oceans' temperatures peak -- late August and early September -- because that's when they have absorbed the most excess solar energy.
Looks like there was a two to three year period during which the seasonal heating effects of reducing aerosols were more substantial than cumulative heating effects. Of course there is a lot of other stuff going on masking these effects.
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https://climatereanalyzer.org/clim/sst_daily/
From being below previous years up to mid March 2023, after that it is above previous years and from late May 2023 it is well above previous years.
Does this seem like a large effect kicking in very rapidly i.e. in just a couple of months?
For sulfur, volcanoes effects can easily last 2 or three years and the volcano has to be eruptive enough to get the sulfur into the stratosphere where it doesn't get quickly washed out of atmosphere.
Perhaps shipping emissions are quickly washed out of atmosphere by rain and this explains the effect kicking in so quickly? But if so, why don't less powerful volcanoes have more effect on temperatures? Can that be adequately explained by large numbers of ships continuously emitting to create lots of small area location effect whereas the volcano affects just one small area for a limited time?
If so, this would probably ease fears that these effects will continue to build up in effect.
AGU session in December (https://www.realclimate.org/index.php/archives/2024/05/new-journal-nature-2023/) called “GC053: Cracking the puzzle of the Anomalous Temperatures in 2023: Observational and modeling studies to identify and understand potential factors and future implications.“ to discuss it. I haven't read realclimate.org in quite a while, while focusing on other things.
Given the uncertainty, I'm waiting to see what September holds as August seems like it will be the last record breaker this year...
Re. HT I don't know what the consensus is regarding its net effect in the medium term (looking back for 2023 I think its disputed whether it net cooled or heated the planet), and now there is a non-peer reviewed paper suggesting that stratospheric humidity will be anomalous for quite a while -- 12-14 years until we return to levels pre HT as a result of the stratrospheric moistening trend + effects from HT ...
I've also switched my position over the last couple months. Sometimes unlikely things happen - in this case, temperatures have stayed warm despite El Niño fading. I try to learn lessons from failed predictions but I'm not sure how wrong I was even in retrospect. I'd be interested in anyone who felt strongly back then making the case I was wrong.
If this year does end up being the hottest ever I'll have barely squeaked out being net neutral on profits.
La Niña does not have a significant on the year it begins in on global surface temperatures, and almost no effect till late fall. Since we had a strong El Niño event entering the year I thought this year would be hotter regardless of an emerging La Niña trend. Also the solar cycle peaked this year.
NOAA's forecast was completely wrong last year as well (even compared to other models) and should probably be ignored. I don't think they spend any time on it.
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If this warmth carries into fall like last year earth is probably already past the 1.5C trend. Also global sea ice extent is about as low as last year (record low).
https://x.com/hausfath/status/1808411956564361542?s=46
Zeke estimates a 95% chance of 2024 being warmest year up from 75% last month
(May be differences in nasa dataset though)
61% estimate from Harvest Program was based on data up to end of April. Zeke's current estimate is based on data up to end of June.
I.e. they are not incompatible. both May, June hottest ever so odds went up.
El Nina/Nino matters more in following year.