Dr. Yue Dong (Columbia Univ.): Antarctic ice-sheet meltwater reduces climate sensitivity and transient warming through the sea-surface temperature pattern effect
Prof. Yi Huang (McGill Univ.): On the strength of stratospheric water vapor feedback
Matt Luongo (Scripps Institute of Oceanography): A surface pathway by which Northern Hemisphere extratropical cooling elicits a tropical response
09:02:55 From Jonah Bloch-Johnson : that website is: https://sites.google.com/tamu.edu/ecs-symposium/home
09:20:58 From Gabriel Chiodo : nice talk! do you have a sense as to why the meltwater needs to be increased by 5x compared to observations in order to match the observed pattern? is the model not sensitive enough or are certain processes missing when it comes to the variations of meltwater and how they affect stratification?
09:22:15 From Gabriel Chiodo : as for the methodology: how do you separate the contribution of OHU and feedbacks? by means of a radiative kernel analysis?
09:22:41 From Neil Cameron Swart : Interesting talk, thanks Yue! Folks might be interested to know there is a coordinated FW hosing experiment going on across models, called SOFIA: https://sofiamip.github.io/. Will be interesting to see if the results hold across models.
09:30:01 From Yue Dong : @Gabriel, thanks. Good question! The CESM1 results could be due to the model being too insensitive, and the amount of freshwater input needed to cause significant changes in the SO is found to be highly model dependent. Would be good to have a range of model simulations to test the model dependence, whether coming from model biases or simply the model sensitivity to meltwater input
09:31:24 From Yue Dong : And I calculate kappa and lambda following the simple energy budget framework, where kappa = dN/dT, and lambda = d(N-F)/dT, using outputs form model simulations
09:33:43 From Nicholas Lutsko (he/him) : @Yue, when you reconstruct dT/dt, are you keeping deep ocean temperatures fixed? It seems like you are from the slides -- does that lead to faster warming?
09:33:52 From Yue Dong : @Neil, Thanks for sharing, that's exciting. Agree that the results need to be examined in other models.
09:36:22 From Sally (she/hers) : @Yue, the SST difference maps for historical and future both show warming in the North Atlantic. Do you know what's causing the warming there? Thanks!
09:38:17 From Yue Dong : @ Nick, I simply use (dF/dt)/(lambda + kappa) to reconstruct dT/dt. I think changes in deep ocean temperatures are reflected in the kappa term?
09:39:44 From Nicholas Lutsko (he/him) : Thanks, is kappa the OHT efficacy or the total OHT?
09:41:16 From Yue Dong : @Sally, good catch! I haven't thought too much about the SST changes in the North Atlantic - presumably due to changes in AMOC? Will look more into that.
09:41:26 From Yuan-Jen Lin : @matt, thank you for the great talk! I wonder if STCs play a role in carrying the cooling to the tropics?
09:42:21 From Yue Dong : @Nick, it's OHU efficiency, defined as dN/dT.
09:43:51 From Matt Luongo (he/him) : @Yuan-Jen— definitely they play a part! I focused on the surface pathway in this study, but we’re interested in looking at the zonally varying, subsurface STC response as well. However, the La Nina establishes itself about 8 years after the onset of forcing, which is a little fast for the STC response (via ventilated thermocline dynamics) to be the sole driver.
09:48:01 From Dessler, Andrew E : @yi huang: do you think the Hunga Tonga eruption will have any climate effect (due to injection of H2O into the stratosphere)?
09:49:34 From Gabriel Chiodo : thanks for the nice talk, Yi!! I am wondering whether you can reconcile your results with another paper (Li and Newman, 2020) using a similar technique (nudging) but another model, which showed a much bigger effect on ECS (10%), which would be more consistent with Banerjee et al., 2019 and Dessler et al., 2013. Is the disagreement due to the details of the technique (nudgning vs locking), or any state-dependences (e.g. both studies taking different stages of their runs into account), or any model-dependency (e.g. related to the specific water vapor pattern)?
09:49:56 From Karsten Haustein : @Yi and @Andi: Was gonna ask the same thing. Millan et al 2022 GRL suggest that this might be the case. They didn't quantify it tho. What's your view?
09:51:37 From Gabriel Chiodo : the other is: are the "tropospheric adjustments" sensitive to the details of the nudging technique, e.g. how do you transition from the stratosphere (fixed water vapor) to the troposphere (free running - changing water vapor)?
09:52:04 From Dennis L Hartmann : Yi, Nice clear talk.
09:52:19 From Robert Pincus : @yi Very nice work. It seems like stratospheric water vapor changes would be tied to surface temperature - so aren't these a feedback, rather than a forcing?
09:55:31 From Gabriel Chiodo : thanks!
10:00:07 From Moritz Günther : I have a question related to Yue's talk: Why do climate models not simulate the melt water from Antarctica? Could they? Should they? Are there any that do?
10:00:46 From Gabriel Chiodo : excellent talks! thanks