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Photo of Ms Femke Nijsse

Ms Femke Nijsse

Postgraduate

Email:

Telephone: 01392 727033

Extension: (Streatham) 7033

PhD
I recently submitted my PhD thesis in mathematics in the Exeter Climate Systems group. My PhD was into finding a theoretical basis for emergent constraints and improving the (statistical) techniques used for them. Emergent constraints are emergent relationships that appear when you have a group of different climate models (an ensemble) in which a mostly linear relationship appears between a variable of past climate and a variable of future climate. Using measurements of the first allows us to exploit this relationship and get a better estimate of our future climate. A theoretical basis is needed to prevent data mining of linear relationships.

I investigated the relationship between decadal variability and climate sensitivity and found that they are positively related in the CMIP5 model ensemble. I explain this relationship using conceptual models of the climate system. I further used emergent constraints in the CMIP5 and CMIP6 ensemble to investigate whether the increased sensitivity in the latter ensemble is consistent with observed warming. More models overheated than underheated in the new ensemble, keeping hope alive that the Paris Agreement goals can be reached.

Supervisors:
First supervisor: Peter Cox
Second supervisor: Mark Williamson

Background:
I completed my Bachelor in Physics and Astronomy at Utrecht University, spending half a year doing modules in biology and geology at the University of Murcia in Spain. My Master's didn't appreciate the strength of short names and was in Meteorology, Physical Oceanography and Climate Physics.  For my master's thesis I worked together with Henk Dijkstra on finding a dynamical underpinning for emergent constraints using linear response theory.

Publications
Nijsse, F.J.M.M. and Dijkstra, H A (2018) A mathematical approach to understanding emergent constraints, Earth Syst. Dynam., 9, 999-1012.

Cox, P.M., Williamson, M.S., Nijsse, F.J.M.M., Huntingford, C. (2018). Cox et al reply Nature 563, pagesE10–E15.

Williamson M.S., Cox P.M., Nijsse, F.J.M.M. (2019). Theoretical foundations of emergent constraints: relationships between climate sensitivity and global temperature variability in conceptual models Dynamics and Statistics of the Climate system 3:1

Nijsse, F.J.M.M., Cox, P.M., Huntingford, C., Williamson M.S. (2019). Decadal global temperature variability increases strongly with climate sensitivity. Nature Climate Change

Nijsse, F.J.M.M., Cox, P.M., Williamson M.S. (2020). Emergent constraints on transient climate response (TCR) and equilibrium climate sensitivity (ECS) from historical warming in CMIP5 and CMIP6 models. Earth System Dynamics 11

Huntingford, C., Williamson, M.S. and Nijsse, F.J.M.M.,  CMIP6 climate models imply high committed warming. Climatic Change (2020),