Interested in how climate model projections have matched up to reality? RealClimate: Comparison Update 2024 www.realclimate.org/index.php/ar... - ThreadSky

climateofgavin.bsky.social • 26 days ago

Interested in how climate model projections have matched up to reality?

RealClimate: Comparison Update 2024 https://www.realclimate.org/index.php/archives/2025/01/comparison-update-2024/

Comments

ogredragon.bsky.social•25 days ago

until now... we didn't notice that curve is really upticking faster than the model..

sarava.net•26 days ago

Question motivated by recent trends in the CMIP6 Global SST plot in the post: Do we "know" the TCR range well enough to justify TCR screening?

climateofgavin.bsky.social•25 days ago

Is there enough evidence to suggest that the high sensitivity models are not realistic? Yes (paleo/transients etc.). So is a screen justified? Yes. But feel free to justify a different range.

sarava.net•25 days ago

I think an ECS screen has stronger justification, but going from knowing ECS to "knowing" TCR ... I'm less sure (ocean uptake etc.)

climateofgavin.bsky.social•25 days ago

doesn't make any difference in these plots.

climateofgavin.bsky.social•25 days ago

Note that the mass of high SST trends come from one model (CanESM5).

ancientgarnet.bsky.social•23 days ago

Has anyone tried to run Hansen's model using actual emissions?

climateofgavin.bsky.social•23 days ago

Concentrations, not emissions, and there weren’t any aerosols, but yes, the EdGCM project is a slightly modified version of the original Hansen et al 83 model.

anlomedad.bsky.social•25 days ago

Last winter UK was so wet it destroyed crops and delayed sowing in spring. How often would this occur in a 1.5C vs 2C world? In 2023, 2/3of Slovenia flooded and 1/3 of Pakistan 2022. Same question.
And how often until sociatal organisation erodes regionally, then globally? Train models for answers👍

jackmott.bsky.social•25 days ago

Its interesting seeing headlines the last couple of years that read like "scientists have no idea why the warming is so fast!" which instills a lack of confidence in climate science, yet, the observed warming remains in the expected range of the occurring scenario's models!

climateofgavin.bsky.social•25 days ago

Well, I've generated many of them. But there is a difference between are the long term trends what we expected? (more or less), and are the specific of the last couple of years difficult to explain? (also yes). Both things are interesting and worth digging into.

jackmott.bsky.social•25 days ago

communicating nuance to large groups is probably impossible. but i will try to understand!

umsonst.bsky.social•26 days ago

I do not think that such a model spread is an indication of model quality just of model differences - models can not simulate mutual amplification of highly dynamical systems whose physical mechanisms operate over small scales - jets, land-ocean-atmosphere coupling, vertical mixing, heatwaves,

umsonst.bsky.social•26 days ago

drought and precipitation extremes etc. which are all underestimated by most or all models depending on what you compare. Question is in how far these extreme system swings can speed up global warming. As weather becomes now climate it could become substantial. E.g. burning of the Amazon or Arctic

ocasapiens.bsky.social•25 days ago

I have a question. If models get the system's energy increase, its thermodynamics. right, what would "swing" cryo-, hydro- etc- dynamics of extreme weather events? What would speed global warming or sea level rise?
Two questions, sory.

umsonst.bsky.social•25 days ago

Its single extreme surface events happening at the same time caused by abnormal circulation patterns which trigger the next abnormal circulation patters causing the next wave of extremes in other places. It kind of a mutual amplification that happens just now...

umsonst.bsky.social•25 days ago

And all these surface temperature extremes then disturb global circulation patterns ever more with regions where high pressure systems just get stuck while i other regions you have exceptional storms and flooding - here the last example, as the large scale (synoptic scale) is important:

umsonst.bsky.social•25 days ago

Another example - sea level rise - single events can have a significant effect on melting polar ice caps - one example 2012 when the whole surface of Greenland was melting for some 3 days - a truly exceptional event. Reasons: https://www.pnas.org/doi/10.1073/pnas.1405397111 which triggers the next internal feedback

umsonst.bsky.social•25 days ago

And circulation patterns can cause massive sea ice losses which then also feeds back on the warming rate. Warm air intrusions caused by blocking patterns melt in one region sea ice, which then feeds back on circulation patterns causing other abnormal air flows in other regions causing e.g. heatwaves

umsonst.bsky.social•25 days ago

And all these regional warmer temperatures caused by abnormal circulation patters can than produces a significant warming signal during a month. Could be one reason of why global temperatures remain so high even that we have a La Nina in place.

umsonst.bsky.social•25 days ago

Next example - the drying of the Amazon - its caused by SST patterns that block moisture to reach the rainforest. This then favors its drying and thereby temperature increase across the rainforest.

umsonst.bsky.social•25 days ago

- also soil moisture get very low, so plants stop to evaporate which then favors low cloud cover over the rainforest which then leads to even higher temperatures. And not concection over the Rainforest can then reduce the trade winds over the North Atlantic which then causes higher SSTs.

umsonst.bsky.social•25 days ago

So a knock-on effect - warmer dryer Amazon supporting warmer tropical North Atlantic.

umsonst.bsky.social•25 days ago

Next marine heatwaves: they are e.g. caused by high-pressure systems during summer (low cloud cover and weak surface winds) - here one from the Southern Ocean - this massive one in the Southern Ocean is low wind speeds and low cloud cover and other causes like stratified surface layer.

umsonst.bsky.social•25 days ago

So lets stay with winds - winter time polar region. No chance that ans significant warm can happen as there is no sun.But winds and a disturbed circulation with wavier jets and blocking patterns and strengthening highs and lows can push massive amounts of warm and moist air into the polar cold cell

umsonst.bsky.social•25 days ago

And these events can cause a significant warming signal as the winter polar air cell suddenly becomes over large regions much warmer than normal. These heatwaves can have >20°C above normal temps. here you have some basis patterns - https://www.noaa.gov/jetstream/upper-air-charts/basic-wave-patterns Blocking Patterns - they redirect air

umsonst.bsky.social•25 days ago

Its complex. A example: winds. If there would exist no winds, energy accumulation would happen at the surface as winds besides GHGs are governing surface temps and heat buildup. Even that a stop of winds would never happen, it shows that other factors besides GHGs and the sun regulate surface temps.

ocasapiens.bsky.social•25 days ago

Tks for taking the time to explain, umsonst!
I took "swing" as sending trends in the opposite direction - not like swinging a bat and hitting - and wondered what could possibly do that iwhen the system heat/energy keeps increasing.

umsonst.bsky.social•25 days ago

I think its a question of the speed of warming - if you warm the climate slowly the warming rates in the different regions are more similar - latitudes. E.g. slower sea ice retreat.

rickwoollams.bsky.social•26 days ago

So I’m new here, but there don’t seem to be any climate science deniers here on Bluesky. Did they all stay at Twitter?

pukite.com•25 days ago

Partly due to the better blocking algorithms. Mostly due to they are satisfied with the tar-pit cesspool that is Xitter. They have their own charter/home school and will stay there

rickwoollams.bsky.social•25 days ago

That works for me.

beaudodson.bsky.social•25 days ago

Computers have been extremely accurate in their forecasts. For decades.

nocloudcover.bsky.social•24 days ago

yeah early 1970 something.

nigel-purchase.bsky.social•25 days ago

These are surprisingly good, not because the science is wrong, but because they must have got the inputs right. My experience of creating models is that you can make a very good model, but then you have to forecast the exogenous variables, and you get *them* wrong!

pukite.com•25 days ago

They still aren't "good" because they don't reproduce ENSO and other climate indices correctly. Yet they are passable for trends.

nigel-purchase.bsky.social•25 days ago

Yeah, but cyclical fluctuations around the trend aren't of interest in climate change analyses, though they are of course important for weather (and don't we know that in Oz!)

The analogy is daily and monthly fluctuations in share prices. Hard to forecast and not important for long-term returns.

pukite.com•25 days ago

Economics is all game theory, irrelevant to physics

nigel-purchase.bsky.social•25 days ago

Nonsense. It's about determining signal out of noise; about understanding underlying models; about small and big cycles; and about long term trends. Which has a lot in common with climate analysis. Both use maths, statistics, probability and logic.

pukite.com•24 days ago

No. Game theory is intractable. That is known. OTOH, geophysical-based climate science has a chance to be tractable. Look here:

https://geoenergymath.com/2024/11/10/lunar-torque-controls-all/

nocloudcover.bsky.social•24 days ago

how is the big debate going?

in grade school we were given about 30 minutes

shouldn't need to a google alert on folks like Gavin Schmidt

the Science op piece a few months ago that seemed to be trying to downplay published papers by Hansen and Leon et al... many papers.

????