Re: [HPAC] Some highly interesting intricacies to cool down a water planet - we have to understand in how far we can cool down Earth as the oceans will work against it
John Nissen
--Hi all, here a study complex that is important in terms of what it means to cool down a water planet...
1: Even if we reduce our emissions fast global warming rates will continue for at least a decade. But nothing less should be suspected, so no real surprise here, just a confirmation that there is warming in the pipeline. Fun fact: the argument that zero emissions and declining GHG levels afterward will cancel out warming effects of ongoing ocean warming is theoretical nonsense. It's simple: the first decades continuing ocean heat uptake will happen at the highest rates while declining GHG levels will need decades to reach a substantial effect - hence there is warming in the pipeline the first decades. While the above study would mean that during the first decade high warming rates continue.
"Constraints on Climate Change Stabilization Based on Observations of Earth's Energy Imbalance"; https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2025GL121056
2: Even under GHG stabilization El Ninos will continue to bulb out heat. They could even become 40-80% stronger. This result which will be correct to some extent at least. It means that while we start to cool the climate down substantially, temperature jumps will still frequently happen at least for some time and which will remain massive.
"Deep ocean warming-induced El Niño changes"; https://www.nature.com/articles/s41467-024-50663-9
3: If we stopped our emissions after centuries, the climate started to cool down the oceans will abruptly burb out heat which will lead to comparable warming rates then anthropogenic global warming. The problem with this result is that they speak of deep ocean heat being brought upward by deep convection. We have now also a massive heat accumulation across the first 700m with distinct hot spots where warm water bubbles grow and warm which are also becoming fresher. This whole line of research is still in its infancy hence it's not clear in how far the mid-latitude oceans will release heat when we cool the climate down.
"Southern Ocean Heat Burp in a Cooling World"; https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2025AV001700
A worst case scenario:
Let's say we start global cooling in the mid 30s when we will have reached a temperature niveau above 2°C - could be even 2.5°C if ocean heat uptake rates now accelerate surface warming what we should suspect along with further cloud declines over warmer oceans. In the first decade global warming will continue driven by ocean heat which we will have additionally to cool down. Hence, we could fast end up needing to cool down the climate by more than 1.5 °C just to stat at the 1.5°C temperature level which temperature jumps still happening.
If we try to cool to such an extent the climate the side effects could be massive while increasing rates of aerosols in the atmosphere will suppress outgoing longwave radiation (OLR) the more we aerolize the atmosphere which will make it harder for the oceans to loose heat to space. This has to be understood: the only way oceans can cool down is via heat loss to the atmosphere, and this heat release would have to be countered by SRM.
Hence, we will have to understand to what extent SRM can cool down the climate against oceans loosing more heat of which more will remain in the atmosphere due to reduced OLR values to space. And for that highly idealized simple model experiments won't do as we would need to simulate current boundary conditions of ocean heat which models are not able to reproduce. Further, models are very bad at deep currents, mixing processes, in part with atmospheric circulation changes, and evaporation parametrizations over the oceans are as well quite simple compared to the complex reality. Hence, maybe we would even need to wait for new high resolution model generations that need much higher computational power than we currently have to understand the above complex.
Just as a reminder that it's not so easy as just to restore Earth's albedo and all is nice and well again. It's not even clear to what extent we can cool the climate down against oceans continuing to warm that try to cool down via heat loss to the atmosphere. As long as we haven't solved these issues we just do not know in how far SRM can work.
Best
Jan
-- Jan Umsonst Wallauer Str. 6D, 30326 Frankfurt am Main Tele: 0176 41114523 E-Mail: j.o.u...@gmail.com Performing Vitality: https://performingvitality.wordpress.com/
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John Nissen
Hi,Tom and me wrote a full article on it, with Kevin Trenberth not denying that we had a strong point so yes I'm aware of it.Fun fact: another leading expert even wants to help Tom and me to make a review study on it, which I'm not able to do as I like to go too much into the details but Tom and me will deliver - Tom pushes me what I need :DAnd that I'm fundamentally wrong is not backed up by science which clearly states that I'm correct. But to what extent will oceans prevent us to cool down the system?Sadly, opinions are more important than scientific facts - the reason I attached the studies but to no avail...The question is only to what extent ocean heat will prevent us cooling down the system?Sure, you can think otherwise but for the physical Earth system our opinions do not matter a bit...Fun fact: Kevin Trenberth mentioned it himself in a study that our main problem is that we have already too much energy in the system and that SRM will make the problem worse as it suppresses OLR to space, while net zero tackles the problem at its root.Advocating SRM comes with a great responsibility as if it goes wrong or does not work as planned we just provided another stepping stone on our staircase to extinction.Therefore, it's especially the SRM community which has to heed the latest science as we have to act accordingly to it.Further, my argument means essentially that we have to start now solar dimming as we have to prevent the oceans from overheating as otherwise the heat in the oceans will become a roadblock at one point to dim down surface temps as much we will need it.Further, if you would have read our article on the feedback complex that we missed you would have realized that stratification first shifts ocean heat uptake to shallower depths which supports higher SST which come with a cloud feedback driving first ocean heat uptake to higher levels.Which then leads to higher rates of latent heat release to the atmosphere. Mid latitudes during winter already becoming operational as a new feedback - studies coming out recently as it is obvious now.Hence, stratification increases ocean heat uptake and heat loss to the atmosphere which then reduces ocean heat content increases as more is lost to the atmosphere.So technically it's incorrect that stratification reduces heat uptake ;)You can ignore the feedbacks, but they won't ignore us...BestJan