In a fascinating journey from the cosmos to the kitchen, Sarah Bridle, a former cosmologist, has now become a champion of food physics. Her story is a testament to the power of curiosity and the potential for interdisciplinary thinking to drive meaningful change. Bridle's transition from mapping dark matter to studying food systems is not just a personal journey but a call to action for scientists and policymakers alike. Her insights offer a unique perspective on how physics can be applied to address some of the most pressing challenges of our time, particularly in the realm of food and climate change.
The Spark of Curiosity
Bridle's interest in food physics was ignited by the late David MacKay, a scientist who made significant contributions to energy and climate research. MacKay's work on sustainability and his insights into the potential of food to influence climate change sparked a passion in Bridle. She reflects, "I began thinking hard about why we do what we do, and what would happen without him doing the fantastic work he led on energy and climate." This personal connection to the topic and her desire to understand the complex interplay between food and climate change drove her to explore this new field.
The Dark Matter of Climate Solutions
Bridle introduces the concept of land use as the "dark matter" of climate solutions. She explains, "Most people aren’t aware that food is responsible for up to a third of global greenhouse gas emissions and, in the UK, about 70% of land is used for agriculture." This realization highlights the significant role that food systems play in climate change. However, she also points out the inefficiencies in land use for food production, which can hinder climate solutions. "The way we use land for food can be extremely inefficient, which blocks those climate solutions." This inefficiency is a critical lever that needs to be addressed.
Social and Cultural Factors Dominate
One of the surprises Bridle encountered in her new field was the dominance of social and cultural factors. She notes, "As a data geek, I expected it to be all about technical solutions but what surprised me was how dominant social and cultural factors are too." This highlights the complexity of food systems, which are influenced by people, incentives, norms, and feedback loops. Bridle emphasizes the importance of understanding these factors to develop effective solutions. "Unless, that is, you pair it with social and cultural change." This realization has led her to combine quantitative modeling with deeper social insight.
The Limits of Astrophysics Tools
Bridle shares an example where astrophysics tools didn’t work in a food context. She attempted to repurpose multispectral satellite-imaging techniques to detect blackgrass in UK wheat fields, but found it too difficult with satellite data alone. "Variables like soil moisture, rockiness and other field conditions confounded the signals." This experience nudged her away from a pure imaging approach toward broader system modeling. "That experience nudged me away from a pure imaging approach toward broader system modeling – and, later, back to data with more contextual integration."
The Future Food Calculator
Bridle and her team developed a quantitative model of the food system, which they turned into a web-based dashboard. "Users can move sliders, explore UK production and consumption, greenhouse gas emissions, self-sufficiency and land use, and ask, ‘Do these choices get us to net zero, and with what trade-offs?’" This tool allows for the comparison of interventions on a common footing, including on-farm practices, consumer dietary shifts, and land-use choices. It provides a practical way to explore the trade-offs and unintended consequences of different interventions.
Handling the People Side
Bridle emphasizes the importance of meeting people where they are, particularly when it comes to demographics and messaging. She notes, "Older generations, on average, are more focused on health than climate. Children and younger people tend to feel invincible about health but are very concerned about climate." This highlights the need for tailored messaging and assumptions in models to effectively encourage dietary change. "If you’re trying to encourage dietary change, those differences matter for messaging and for assumptions in models."
Information vs. Behavior Change
Bridle shares insights from obesity research, which shows that giving people information often doesn’t change behavior. However, it does increase receptiveness to policy. "We need systemic changes that make sustainable choices easy by default, and public understanding helps make those changes legitimate." This highlights the importance of creating an environment where sustainable choices are the norm, rather than relying solely on individual behavior change.
Creating Wow Factor for the Food Industry
Bridle discusses the challenge of creating a "wow" factor for the food industry, which often has a disconnect between food and its production. She suggests that experience helps more than pictures. "Community garden projects, for example, let people see how hard it is to grow food and how weather drives yields." This fosters respect for food, reduces waste, increases interest in the natural world, and builds practical resilience.
Environmental Labeling
Bridle advises on environmental labeling, suggesting that labels should have a significant impact upstream on what gets produced. She notes, "In pilot programs, adding climate labels led operators to change what they offered once they saw the differences." This highlights the power of labels to influence production practices and drive positive change.
The Digital Twin of UK Food
Bridle and her team are building a digital twin of the UK food system, which will allow them to test interventions and assess their impact on greenhouse-gas emissions and self-sufficiency. "We take UK production and consumption, feed use and losses, and then we test interventions and see how they affect greenhouse-gas emissions and self-sufficiency." This tool will help interrogate trade-offs and unintended consequences, and assess whether a bundle of changes can hit net-zero targets while maintaining resilience.
Managing Complexity
Bridle discusses the complexity of managing interventions like herbicides like glyphosate. She explains, "No-till – an agricultural technique that plants crops without disturbing the soil through traditional ploughing or tilling – can reduce emissions but may increase reliance on herbicides if weed pressure rises." This highlights the need to quantify these interactions at the system level and compare pathways transparently.
Data Practices in Food Physics
Bridle compares the data practices in food physics to those in astrophysics, noting the differences in collaboration, open data, and code. She suggests, "We need standards, shared datasets, open code and co-ordinated efforts." This is particularly important in the context of climate change, where opacity is not defensible. "Even at the policy interface there are gaps: you might get a major report with spreadsheets but not the underlying code or assumptions, which we then have to reverse-engineer."
Advice for Aspiring Food Physicists
Bridle offers advice for physicists or mathematicians who want to follow in her footsteps. She suggests, "Quantitative modelling, open-source practices and Python-based tooling are highly sought after right now. Help build transparent models and shared datasets, and join or create collaborative efforts that mirror modern astrophysics consortia." She also emphasizes the importance of finding one's people and adopting mentors.
A Concrete Step
Bridle encourages a concrete step for those interested in this field: "One is to bring open-science habits to food-system work: publish code and assumptions, contribute quantitative skills to cross-disciplinary teams, help build shared datasets and reproducible models, and translate findings into accessible tools – like interactive calculators – for policymakers and the public."
Motivation and Success
Bridle's motivation is rooted in her desire to help with the crisis we’re walking into. "My motivation is about doing what I can to help with the crisis we’re walking into. It’s a way to channel worries about the future into practical improvements." Looking a decade ahead, she envisions success for the UK food system as being aligned with net-zero targets and efficient land use, which will enable other climate solutions to scale. "I also hope that self-sufficiency and resilience improve – and that open, quantitative modelling with transparent code and assumptions is embedded in policymaking."
Sarah Bridle's journey from cosmology to food physics is a powerful example of how interdisciplinary thinking can drive meaningful change. Her insights offer a unique perspective on the potential for physics to address some of the most pressing challenges of our time, particularly in the realm of food and climate change. Her work is a call to action for scientists and policymakers to embrace the power of physics and collaborate to create a more sustainable future.
