I am originally from Switzerland, but spent most of my childhood (between the ages of 6-16) in Guinea, Africa, since my parents worked there in an NGO associated with teaching.

I was interested in nature and in plants from an early age and even tore down our small vegetable plot in the family garden in Guinea in an attempt to plant trees instead. This of course was not very appreciated by my parents, but shows my strong affinity to plants since childhood. In addition, the effects of climate change on the weak and poor population was very evident and affected me. I heard the farmers worry that the dry seasons were getting longer and hotter. 

This motivated me to study environmental science at ETH Zurich when I returned to Switzerland, as it integrated all the different scientific disciplines that interested me: biology, chemistry, meteorology, and physics, and offered an interdisciplinary approach to the issue of climate change. In rich and developed countries, there are a vast array of options, both technological and scientific, to tackle the challenges of climate change, while in poor and underdeveloped countries this challenge is very hard to confront. My idea was to learn and study as much as possible about these topics in order to be able to offer solutions that can be applied worldwide and not only in those countries that can afford to purchase and implement these solutions.

At early age I read that dry areas constitute about 40% of the planet and I realized that the only way to study these areas is to conduct research in one of the driest areas on the globe, rather than in an office somewhere in Europe. That is why I chose to come to Israel, which I knew had excellent research facilities and leading scientists, and is a very dry area to explore. Israel also interested me from a broader geopolitical perspective for being the Middle Eastern country constantly preoccupying the UN, and I was interested to experience it in person.

I was introduced to Prof. Dan Yakir by his colleagues at KIT in Germany. This led to me joining Dan’s group for my PhD, although my original background was somewhat different and it took me about a year to study and work hard to overcome my knowledge gaps, but it was certainly a rare and unique opportunity for me to have been able to come to WIS and do my PhD in Dan’s group. One of the most important aspects of the work in the Yakir group was the fact that students such as myself also became “expert technicians.” By working at the Yatir forest station, I had a chance to acquire new skills needed to design and develop different systems, such as a highly precise leaf temperature measurement system and key components of the gas exchange systems in Yatir. Import restrictions for infrared cameras meant that I ended up salvaging and repairing an old infrared camera from the WIS’s solar tower, which I was then able to use as a vital tool for conducting my research.

During my PhD at WIS, I examined tree energy management under extreme drought and heat (>35°C), demonstrating that trees are able to maintain leaf temperatures within 5°C of the ambient air temperature in the field, in spite of the lack of evaporative cooling. This is achieved by decreasing aerodynamic resistance to heat transfer. During this project, I designed and built entire novel measurement systems in harsh field conditions, including electronics and their programming, developed advanced data processing techniques, and substantially supported the work of my colleagues. Beside my PhD project, I also participated in a project indicating that monitoring gross primary productivity (GPP) during heat waves using sun-induced fluorescence may be difficult due to the lack in changes of absorbed photosynthetically active radiation. I helped develop a canopy identification method required to assess NDVI from satellite data, as it is otherwise dominated by soil signals in sparse semi-arid ecosystems, and I developed the gas flux measurement system and calculation methods for a project containing 16 branch-scale gas exchange chambers, among other projects I worked on that are still being prepared for publication. Following my PhD, in a 1-year bridging postdoc at the WIS with my co-fellow Rafael Stern, I then scaled up to include ecosystem carbon and energy fluxes in a study with a unique comparison between the climate change mitigation potential of land cover changes through afforestation vs. the installation of solar panel fields. This study demonstrated the similarity in increased heat loads of both land cover changes and the efficacy of emission reductions, and drew my attention towards the climate effects of planned large-scale land cover changes. Finally, I participated in a study showing that the global-scale water yield will drop much faster than precipitation rates, thus likely leading to significant land cover changes.

I heard about the program from my friend and colleague Rafael Stern, who took part in the program in its first year. At first I had other things on my mind and thought that my research would not fit the Fellows program and its goals, but after many talks with Rafael I was finally persuaded to apply and was accepted in the second year of the program.

I believe the interdisciplinary of the discussions within the IES Fellows meetings was the strongest point of the group. These discussions broadened the scope of my experience at WIS, since they made me think outside the relatively narrow topic of my PhD. It enabled me to develop a more critical way of thought and also served as an opportunity and platform to suggest and initiate new ideas. It also taught me to develop a more open-minded approach towards the general idea of sustainability related research as an umbrella with a broader impact and scale, rather than focus only on my personal PhD research, which naturally preoccupied me most of the time.

In general, WIS has budgets to support research in a variety of directions and scales, but at my current institute in South Africa this is not possible at the same scale, as funds are not so abundant. On the other hand, WIS is an Institution for students studying for their MScs and higher degrees, and therefore there is almost no chance for PhD students to gain teaching experience. I think this is something that is missing at WIS and should be strengthened and supported, since teaching experience is very important later on in an academic career. In particular, with respect to the IES and the Fellows program, I think it is very unique, as it connects between people from different departments and disciplines in an intimate, informal manner. At ETH for instance, the environmental science program is a separate faculty, and while the studies are interdisciplinary in substance, in practice the students in this program do not interact with students from other faculties much.

I also see the importance of the network of IES fellows which was created during the time I was a Fellow and is continuing to grow every year. I think it is very important to keep this network and further strengthen and develop it, as it is very beneficial both for the active Fellows during the regular meetings, in the various activities and lunches, and also after Fellows leave for postdocs or work elsewhere, as a hub for keeping in touch with current activities and with WIS in general.

I would like to stay in academia, although this path has its difficulties, and hope to be able to do so after my postdoc ends in about 2-3 years. I think that studying and learning as much as possible about climate change is the key to gaining a deeper and better understanding of the current crisis and for trying to offer the best solutions in the path we take to confront the immediate challenges humanity is currently facing. Returning to WIS is also definitely an option I keep in mind.

Jonathan completed is B.Sc. in Environmental Sciences at ETH Zurich (2007-2011). He then completed his M.Sc. studies in Environmental Sciences, majoring in Forest and Landscape management at ETH Zürich (2011-2013). Following that, Jonathan conducted a one year civil service at the Cantonal Administration of Zürich, Switzerland (2013-2014) in the agency for nature protection, during which he participated in historical data digitization of plant species distribution and in surveys of plant distribution in protected habitats, including resettlement efforts of endangered plant species. In 2014-2015, he worked at the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) where he participated in a project on drought effects on tree seedling establishment in the group “Disturbance Ecology” (Forest Dynamics). In 2016, Jonathan joined the Weizmann Institute for a Ph.D. at the Department of Earth and Planetary Sciences under the supervision of Prof. Dan Yakir (2016-2022).

Jonathan was awarded the Swiss Friends of the Weizmann Institute Postdoc fellowship (2021) and the Sustainability and Energy Research Initiative (SAERI) PhD fellowship (2019).

Jonathan is currently a postdoc researching the effect of land use change on climate change parameters in African ecosystems at Guy Midgley’s lab at the School for Climate Studies at Stellenbosch University, South Africa. During his MSc at ETH Zurich, he was able to demonstrate the significant facilitatory effects of tree canopies supporting their understory vegetation along a rainfall gradient spanning from coastal forest to savannas, showing the importance of trees in a drying climate. This was followed by a study examining drought effects on root growth of pine and douglas fir saplings in Switzerland, which showed improved drought resilience in the native species. Jonathan completed his PhD in Ecophysiology, titled “Linking ecosystem productivity to radiative and non-radiative energy management in semi-arid forests” at the Weizmann Institute of Science, under the supervision of Prof. Dan Yakir of the Department of Earth and Planetary Sciences.

In his postdoc work, Jonathan uses a combination of ecosystem and plant- and ecosystem-scale measurements, aiming at quantifying the effect of land cover change in Southern African ecosystems on a variety of climate change parameters. He is currently focusing on the balance between changes in surface energy budget, leading to climate warming and carbon assimilation, resulting in cooling. Jonathan has previously uncovered a fundamental mechanism keeping tree canopies cool under drought and heat, showing an important factor that supports resilience to a changing climate. This project will yield important insights for future land management, which is urgently needed in the fragile and insufficiently studied African ecosystems.
Beyond his academic work, Jonathan is passionate about landscape photography, gardening, and has supported the work of World Relief Germany in East Africa on a volunteer advisory basis in the past.