I am very excited about this point: it makes a huge difference whether we analyse raw data, changes from the "present day", or from "pre-industrial" in our models. Changes from the "present day" can mean projecting forward current variability and add potentially spurious uncertainty to projections.

PhD Graduation!!
Very happy to finally graduate from my PhD, focusing on Southern Ocean Centennial Oscillations in the CMIP6 Ensemble”. I am incredibly grateful to all those who have supported me throughout, friends, family and colleagues (too many to name here,please check out my acknowledgements).

Thank you so much to @bas.ac.uk and @cambridgemba.bsky.social for inviting me to speak to their Executive MBA group about the economic impacts of climate change and the use of climate information in decision-making.

Really looking forward to presenting my work on the Economic consequences of CMIP Diversity and Targets for CMIP7 at #EGU25, do drop by if you would like to learn more about climate model uncertainty and its relevance for economic modelling.

Finally, the thesis also shows that under global cooling (perhaps due to a future overshoot in temperatures), the Southern Ocean becomes destabilised, triggering new and faster oscillations (such as in the Antarctic Circumpolar Current), and even a counterintuitive loss of sea ice in some sectors.

As centennial variability dominates the uncertainty in some of the Southern Ocean, this shutdown in variability dominates the behaviour of uncertainty in features (e.g. the Antarctic Circumpolar Current), so the initial oscillation state accounts for a large amount of uncertainty in trajectories.

Applying global warming forcing to the system leads to the shutdown of convection and the loss of the oscillatory behaviour (shown in figure). Under plausible future scenarios (SSP scenarios for CMIP), this shutdown occurs even with strong mitigation, suggesting a tipping point may have been passed.

These oscillations involve multiple mechanisms, both the more traditional heat release behaviour and a novel advective mechanism involving the gyres. While both mechanisms involve deep convection, the advective mechanism involves motion of heat around the gyre (shown in the figure).

Centennial (roughly hundred year period) oscillations exist in the Southern Ocean across the CMIP6 ensemble of climate models. These oscillations can be seen in many features such as the ocean heat, currents (such as the Antarctic Circumpolar Current, shown in the figure), and dense water formation.

Very happy to announce I have submitted the final printed and bound version of my PhD thesis “Southern Ocean Centennial Oscillations in the CMIP6 Ensemble”! It is also now accessible online: www.repository.cam.ac.uk/items/f8e627.... More details in the thread:

"How to cope with climate uncertainties in strategic decisions" at Evidence Week.

This week David Stainforth and I are at
#EvidenceWeek
in Parliament with Sense about Science to present research evidence on "How to cope with climate uncertainties in strategic decisions" to parliamentarians.

New Paper: Understanding polar ice sheets is critical for predicting future climate
www.nature.com/articles/s43...
Image Credit: Povl Abrahamsen