Assessing future effects on lake ecosystem resilience using data analysis and dynamic modelling.
Based in: University of Geneva
Objectives: highly non-linear systems such as climate are invariably characterized by thresholds, some that may be irreversible often referred to as “tipping points”. There is therefore a need to explore more fully the role of non-linear behaviour in particular on the advent of extreme events that could have an impact on the response of lake waters. In mid-latitude regions, lake physical, chemical and biological characteristics can be significantly disrupted when subjected to intense/persistent heat-waves, and both extremes of precipitation (droughts and floods). However, even in the absence of extreme events, the long-term rise of atmospheric temperatures can also lead to sustained changes in lake functioning through increased stable stratification in the upper layers of a lake. This can lead to a progressive shift towards a situation where the wintertime overturning of surface waters and the oxygenation of deep waters no longer occurs. The overall objective of this project will be to identify thresholds in lake biogeophysical and biological characteristics that could be induced either by progressive changes in climate or through shorter-lived extremes, assess whether these are irreversible or not, and investigate future changes in these extremes on tipping points. The following tasks will be undertaken:
- Assess HFM data for lakes and the neighbouring atmosphere to identify past climate-induced tipping points.
- Use these data to calibrate coupled atmosphere-lake models previously developed and used at the University of Geneva
- Run models in predictive mode to investigate the role of projected changes in climates on the biogeophysical response.
- Explore the consequences of climate induced changes in biogeophysics, in particular lake thermal structure for nutrient availability and distribution as well as the consequences for phytoplankton in deep alpine lake systems, using coupled hydrodynamic – biological lake models.
This student will be based in University of Geneva hosted by Prof dr Bastiaan Ibelings, jointly supervised with Dr Stéphane Goyette, and co-supervised and spend study time with Dr Don Pierson, Uppsala University. The PhD will student will receive a PhD degree from both the University of Geneva and Uppsala University.