Linus Vogt
@linusvogt.bsky.social
Postdoc at NYU Courant Institute 🌱 Ocean heat, carbon, oxygen
Thanks for your interest and I'm glad you liked this part. I'm certainly no expert on these instrument uncertainties, but for our purposes they ended up being negligible relative to the scales of interest (i.e., model bias and inter-model spread in sea ice extent).
October 8, 2025 at 6:00 PM
Thanks for your interest and I'm glad you liked this part. I'm certainly no expert on these instrument uncertainties, but for our purposes they ended up being negligible relative to the scales of interest (i.e., model bias and inter-model spread in sea ice extent).
That sounds really interesting, let me know when there is a preprint!
Funnily enough, using HadISST in our study would also have led to an exaggerated "conservative" estimate of high warming, since then the models would underestimate Antarctic SIE even more. But fortunately we are not sailors.
Funnily enough, using HadISST in our study would also have led to an exaggerated "conservative" estimate of high warming, since then the models would underestimate Antarctic SIE even more. But fortunately we are not sailors.
October 2, 2025 at 8:21 PM
That sounds really interesting, let me know when there is a preprint!
Funnily enough, using HadISST in our study would also have led to an exaggerated "conservative" estimate of high warming, since then the models would underestimate Antarctic SIE even more. But fortunately we are not sailors.
Funnily enough, using HadISST in our study would also have led to an exaggerated "conservative" estimate of high warming, since then the models would underestimate Antarctic SIE even more. But fortunately we are not sailors.
Thanks for the clarification!
October 2, 2025 at 6:25 PM
Thanks for the clarification!
Special thanks to @polarocean.bsky.social who had the initial idea for this project, and to all coauthors: @jbsallee.bsky.social, Casimir de Lavergne, @froeltho.bsky.social, and Lester Kwiatkowski.
October 2, 2025 at 10:49 AM
Special thanks to @polarocean.bsky.social who had the initial idea for this project, and to all coauthors: @jbsallee.bsky.social, Casimir de Lavergne, @froeltho.bsky.social, and Lester Kwiatkowski.
📈 As CMIP6 models underestimate historical Antarctic sea ice extent on average, this leads to an upward correction of climate projections by 2100 under all considered scenarios:
- OHU +3–14%
- Cloud feedback +19–32%
- Global surface warming +6–7%
- OHU +3–14%
- Cloud feedback +19–32%
- Global surface warming +6–7%
October 2, 2025 at 10:49 AM
📈 As CMIP6 models underestimate historical Antarctic sea ice extent on average, this leads to an upward correction of climate projections by 2100 under all considered scenarios:
- OHU +3–14%
- Cloud feedback +19–32%
- Global surface warming +6–7%
- OHU +3–14%
- Cloud feedback +19–32%
- Global surface warming +6–7%
Thus, the state of Antarctic sea ice today quantifies the potential for global climate change in the future.
More sea ice now → more warming later
This is evident as a strong correlation across CMIP6 models (and it also holds in CMIP5)
More sea ice now → more warming later
This is evident as a strong correlation across CMIP6 models (and it also holds in CMIP5)
October 2, 2025 at 10:49 AM
Thus, the state of Antarctic sea ice today quantifies the potential for global climate change in the future.
More sea ice now → more warming later
This is evident as a strong correlation across CMIP6 models (and it also holds in CMIP5)
More sea ice now → more warming later
This is evident as a strong correlation across CMIP6 models (and it also holds in CMIP5)
The constraint is based on Antarctic sea ice extent 🧊
Models with more sea ice today also simulate colder Southern Ocean SSTs, a colder deep ocean, and more mid-latitude cloud cover.
In the future, these models lose more sea ice and clouds, amplifying SW cloud feedback, surface warming, and OHU.
Models with more sea ice today also simulate colder Southern Ocean SSTs, a colder deep ocean, and more mid-latitude cloud cover.
In the future, these models lose more sea ice and clouds, amplifying SW cloud feedback, surface warming, and OHU.
October 2, 2025 at 10:49 AM
The constraint is based on Antarctic sea ice extent 🧊
Models with more sea ice today also simulate colder Southern Ocean SSTs, a colder deep ocean, and more mid-latitude cloud cover.
In the future, these models lose more sea ice and clouds, amplifying SW cloud feedback, surface warming, and OHU.
Models with more sea ice today also simulate colder Southern Ocean SSTs, a colder deep ocean, and more mid-latitude cloud cover.
In the future, these models lose more sea ice and clouds, amplifying SW cloud feedback, surface warming, and OHU.
Check out the full paper for a detailed analysis of all the inter-model links between stratification patterns, overturning, MLD, and OHUE.
Huge thanks to my (now former 🥲) PhD advisors, @jbsallee.bsky.social and Casimir de Lavergne!
Huge thanks to my (now former 🥲) PhD advisors, @jbsallee.bsky.social and Casimir de Lavergne!
June 23, 2025 at 1:35 PM
Check out the full paper for a detailed analysis of all the inter-model links between stratification patterns, overturning, MLD, and OHUE.
Huge thanks to my (now former 🥲) PhD advisors, @jbsallee.bsky.social and Casimir de Lavergne!
Huge thanks to my (now former 🥲) PhD advisors, @jbsallee.bsky.social and Casimir de Lavergne!
We further find that the previously assumed importance of the AMOC for OHU efficiency can be explained by an inter-hemispheric connection in stratification strength between these two regions.
As CMIP6 models are too stratified in precisely these regions on average, they tend to underestimate OHUE.
As CMIP6 models are too stratified in precisely these regions on average, they tend to underestimate OHUE.
June 23, 2025 at 1:35 PM
We further find that the previously assumed importance of the AMOC for OHU efficiency can be explained by an inter-hemispheric connection in stratification strength between these two regions.
As CMIP6 models are too stratified in precisely these regions on average, they tend to underestimate OHUE.
As CMIP6 models are too stratified in precisely these regions on average, they tend to underestimate OHUE.
We show that upper-ocean stratification inhibits OHU efficiency in the Southern Ocean and the subpolar North Atlantic.
This is because stratification in these regions is linked to large overturning cells: the Southern Ocean upper cell and the AMOC.
This is because stratification in these regions is linked to large overturning cells: the Southern Ocean upper cell and the AMOC.
June 23, 2025 at 1:35 PM
We show that upper-ocean stratification inhibits OHU efficiency in the Southern Ocean and the subpolar North Atlantic.
This is because stratification in these regions is linked to large overturning cells: the Southern Ocean upper cell and the AMOC.
This is because stratification in these regions is linked to large overturning cells: the Southern Ocean upper cell and the AMOC.
So which oceanic parameters are responsible for setting the value of the OHU efficiency?
Many answers have been previously proposed, including AMOC strength, mixed layer depths, and stratification.
In our paper, we use an ensemble of CMIP6 models to disentangle this issue.
Many answers have been previously proposed, including AMOC strength, mixed layer depths, and stratification.
In our paper, we use an ensemble of CMIP6 models to disentangle this issue.
June 23, 2025 at 1:35 PM
So which oceanic parameters are responsible for setting the value of the OHU efficiency?
Many answers have been previously proposed, including AMOC strength, mixed layer depths, and stratification.
In our paper, we use an ensemble of CMIP6 models to disentangle this issue.
Many answers have been previously proposed, including AMOC strength, mixed layer depths, and stratification.
In our paper, we use an ensemble of CMIP6 models to disentangle this issue.
In observations, the OHU efficiency in recent decades was around 0.6 W/m² per °C of global warming (Cael 2022, doi.org/10.1029/2022...).
However, current-generation climate models simulate a large range of values for this quantity, almost spanning a factor of 2:
However, current-generation climate models simulate a large range of values for this quantity, almost spanning a factor of 2:
June 23, 2025 at 1:35 PM
In observations, the OHU efficiency in recent decades was around 0.6 W/m² per °C of global warming (Cael 2022, doi.org/10.1029/2022...).
However, current-generation climate models simulate a large range of values for this quantity, almost spanning a factor of 2:
However, current-generation climate models simulate a large range of values for this quantity, almost spanning a factor of 2:
The ocean buffers climate change by removing heat from the atmosphere and storing it at depth.
This effect can be quantified by the "ocean heat uptake efficiency", the amount of heat uptake per degree of global warming.
OHU efficiency = OHU / ΔT
This effect can be quantified by the "ocean heat uptake efficiency", the amount of heat uptake per degree of global warming.
OHU efficiency = OHU / ΔT
June 23, 2025 at 1:35 PM
The ocean buffers climate change by removing heat from the atmosphere and storing it at depth.
This effect can be quantified by the "ocean heat uptake efficiency", the amount of heat uptake per degree of global warming.
OHU efficiency = OHU / ΔT
This effect can be quantified by the "ocean heat uptake efficiency", the amount of heat uptake per degree of global warming.
OHU efficiency = OHU / ΔT