Research Interests

Smallholder Agriculture

Most farmers worldwide are smallholder

Four out of five farmers worldwide are smallholders. They own and work land that is very small, often with the help of their family. Smallholder farming is mainly prevalent in low-and middle-income countries but is important elsewhere. Seventy percent of all farms in the EU are less than five hectares, often even less than two hectares.
Smallholders are a very heterogenous group and they face different challenges and outlooks. While for example less than 10% of all smallholders in Ghana are subsistence farmers – they consume what they produce, more than 30% are commercial farmers – they sell most of their produce.
Smallholders often struggle as their land is too small to feed a family and they tend to belong to the poorest people. Increasing agricultural productivity, improving access to land, supporting vulnerable groups, promoting commercialization of agriculture, and protecting natural resources are often key objectives of research and development projects working with smallholders.

The power of many

While individually smallholders are easily overlooked, as an entire sector, they provide important services to the environment and to people living in the cities. Smallholders tend to preserve biodiversity on their land for example and in some countries provide two thirds of all food produced.
Our aim is to integrate research on smallholders into larger scale and quantitative climate, agriculture and resilience assessments to contribute to improved outcomes for the sector. We research the entire sector, develop methods to consider differences between different groups, work with data on the smallest possible level, individuals to households, and find solutions that can benefit their livelihoods. In this way we can inform the selection of case studies working with individual smallholders in more targeted development projects. We can also compare groups of smallholders facing similar changes in climate and climate variability, but achieving very different outcomes.
Including the smallholder sector in climate risk and resilience research is critical in the Global South. They are among the people expected to be hit hardest by climate change because of their low adaptive capacity.


Climate change impacts and adaptation in agriculture

Hotspots of climate change impacts

Climate change impacts are felt differently in different parts of the world, and depends on the exposure, vulnerability and adaptative capacity of an agricultural system. Our work helps to understand where the hotspots of climate change impacts under different scenarios are. In addition, natural climate variability - internally generated within the climate system - can already today be very large. In tropical and subtropical regions this means that year-to-year or within year variability of rainfall can be very large, a drought followed by a flood followed by a drought.


A glimpse of the future: impact models for agriculture

Climate impact models are well validated and tested for different sectors, including agriculture, and they provide initial evidence on how humans change the climate system and which risks evolve from that. For agriculture, they are process-based computer models that primarily simulate the biological consequences of a changing climate and can be coupled with global climate models and economic and land use models. They simulate plant growth, phenology and development and the carbon and water balance.


One key input apart from climate data are crop, soil and water management to mimic the strategies that farmers use on their fields as best as possible, for example irrigation, fertilizer use and crop and cultivar choice. With a spatial resolution of half a degree latitude/longitude and global extent this is a challenging task but necessary to consider adaptation. We aim at improving such global management datasets for example to represent tropical and subtropical cropping systems in a more accurate way.


Another challenge of modelling changes in agricultural systems with climate change is that the impact models consider less than 10% of the crops cultivated worldwide – the major ones that together cover about 80% of the global cropland. Important horticulture and perennial crops are often not represented and the development and validation of specialized crop models for each of them does take very long. The vulnerabilities of such sectors can be estimated in collaboration with industry and farmers associations, using alternative methods.