Avoiding collateral effects of climate action

“Everything is connected with everything else – that is the core tenet of the nexus approach,” explains Professor Marianela Fader. In this fresh scientific field, researchers study the interplay of four systems: water, food, energy, and nature. “We analyze their connections and interactions and try to project them. In doing so, we ask ourselves: How can I create synergies for all sectors of the nexus – and avoid negative effects?” Nexus research is a “very broad and complex field” that ranges from basic research to practical applications.

Since July 2022, Marianela Fader has been Chair of Physical Geography and Nexus Research at the Department of Geography at LMU. Having studied geography in Göttingen, she wrote her doctoral thesis on the modeling of agricultural ecosystems and hydrology at the Potsdam Institute for Climate Impact Research, where she also did postdoctoral research. During that time, she advised the World Bank Group on climate action and research, before moving to the Mediterranean Institute of Marine and Terrestrial Biodiversity and Ecology in the south of France.

“In addition to climate impacts on food and water security, we researched the nexus there, asking if future irrigation in the Mediterranean area can be driven by photovoltaic panels,” recalls Fader. In a further advisory role for the World Bank Group, she analyzed the effects of climate change on agricultural yields in the Middle East and North Africa. Then she moved to Koblenz to become Deputy Director of the International Centre for Water Resources and Global Change, before taking up her chair at LMU last summer.

Ecological restoration protects ground water

Part of nexus research is learning from historical examples. “As a case in point, promoting bioenergy plantations as a way of combating climate change was a good idea in principle,” says Fader. “But switching to varieties of crops like palm oil, soya beans, and maize that were suitable for biomass energy ended up endangering the food security of precisely the most vulnerable population groups. Moreover, in some regions the plantations were irrigation-intensive and caused water scarcity in several regions of the world.”

Sometimes, however, there are positive nexus effects. A good example is ecological restoration, which is often carried out for reasons of environmental protection or flood defense. Wetlands, for instance, filter water naturally and thus clean the ground water. “A scientific consensus has now formed that climate actions very frequently have positive benefits on the food, water, and energy supply.”

With various methods drawn from neuroscience, physics, mathematics, and other disciplines, nexus researchers attempt to quantitatively describe the interactions and behaviors of the individual systems, which are all complex in their own rights, and also as a “supra-system”. “Our goal is to create a meta-complex nexus system that also takes into account external influences such as demographic trends and climate change,” says Marianela Fader.

“No perfect solution”

The nexus approach comes with “big methodological challenges,” notes Fader. “How do we reconcile the findings of hydrologists, agricultural scientists, geographers, economists, meteorologists, and engineers? And how do we reach political decision-makers with our insights?” A practical problem, moreover, is the administrative and competence silos that often exist in state bodies and ministries. “Despite our ambition to develop generalizable, transferable solutions, we must nevertheless accept that there is no perfect nexus solution for all regions and all situations.”

This particularly applies when it comes to countries with unstable or crisis-ridden regimes. In developing nations, some measures are more difficult to implement – while others are actually easier. “When founding new institutions, they can be designed to be nexus-suitable from the outset.” Moreover, there are areas of the developing world where certain disadvantageous processes have not yet happened. “Take rivers, for example – we straightened them, reinforced them, built on the flood plains, and sealed the soil surface. All this has led to flooding, high water velocities, sedimentation, and erosion,” says Fader. “In several projects in Africa, we’re trying to avoid such problems from the start by building nature-based infrastructure.”

Within an international scientific network, Fader is also working on a nexus report for the Mediterranean area. “This region is not only ecologically important as a hotspot for biodiversity, but there are also many social and economic aspects at play here – which also have a bearing on migration. Besides, this region is also a hotspot for climate change impacts”. In another international project, researchers are projecting a number of sustainability targets of the Agenda 2030 on to the other nexus domains and with the aim of advising political decision-makers accordingly.

“Connections are essential”

She sees many possible connections with other subjects at LMU. “The traditional separation between the natural and social sciences, for example between geography and economics, no longer exists. Land-use change and food security are too closely linked for those old partitions to hold.” Outside of the geographical sphere, Fader wants to build up contacts with computer science in particular – such as using AI when handling large data volumes in modeling. “And there could also be interfaces with biology, physics, economics, and statistics.”

She has very good contacts with the Technical University of Munich “in areas such as water and food science,” and also with the Max Planck Institutes and the Potsdam Institute for Climate Impact Research, which is a member of the Leibniz Association. She also has many international connections. “You cannot research the nexus alone,” says Marianela Fader. “Connections and cooperation are essential.”