Drivers and distribution of global ocean heat uptake over the last half century

Montag 26.06.2023, 11:00 → 12:00 Europe/Berlin

Speaker: Maurice Huguenin, 
Climate Change Research Centre, University of New South Wales (UNSW), Sydney, Australia

Where?    online only via zoom 
https://geomar-de.zoom.us/j/89118120404?pwd=cnQxNVdTSHJZUy9DSk9xNGVsNHBOdz09 

Meeting ID: 891 1812 0404 
Passcode: 067593

 

Abstract:  
Since the 1970s, the ocean has absorbed almost all of the additional energy in the Earth system due to greenhouse warming. However, sparse observations limit our knowledge of where ocean heat uptake has occurred and where this heat is stored today. In this seminar, I first present how I equilibrated a reanalysis-forced global ocean-sea ice model to the 1970s using a spin-up that improves on earlier approaches. Then, I highlight how my PhD supervisors and I investigated the recent ocean heat uptake trends basin-by-basin and associated separately with surface wind trends, thermodynamic properties (temperature, humidity and radiation) or both. We find that wind and thermodynamic changes each explain ~ 50% of global ocean heat uptake, while Southern Ocean forcing trends can account for almost all of the global heat uptake signal. This ocean heat uptake is enabled by cool sea surface temperatures and sensible heat gain when atmospheric thermodynamic properties are held fixed, while downward longwave radiation dominates when winds are fixed. These results address long-standing limitations in multidecadal ocean-sea ice model simulations to reconcile estimates of ocean heat uptake, transport and storage. As a bonus, I will also present results from my third PhD thesis chapter on the link between ENSO and subsurface warming of the West Antarctic continental shelf.