Professor Sarah Bridle

Sarah Bridle (Chair of Food, Climate and Society in the Department of Environment and Geography) on how what we eat affects climate change, why talking about it matters and why we need a more resilient food system.

Your current research focuses on food and climate change but you started out in astrophysics - why did you change track?

About ten years ago I’d just finished working on a huge project to measure the shapes of millions of galaxies to make the largest ever maps of dark matter. It was the culmination of 20 years of research and my team measured the amount and distribution of dark matter using the largest optical imaging survey available.

Then my kids started school and I started to think about what the world would be like for them and what I’d say to them one day when they asked about what I’d done about climate change.

I began reading research papers and one of the things I learnt that really surprised me was that food causes about one third of all greenhouse gas emissions. That was when I decided to take my experience analysing pictures of stars and the night sky, and refocus it on Earth. 

Why does the food system need to change?

The food system causes about one third of global greenhouse gas emissions. To put it into context, currently the food system alone will cause two degrees of warming by the end of the century if we keep going as we are.

A lot of focus around emissions is around ‘clean energy’ but even when we’ve developed the solutions to decarbonise the energy system, the problems around the food system will still be there and will continue to grow.

How will climate change affect what we eat in the future?

Extreme weather caused by climate change already affects the food that farmers can grow here in the UK. Recent data from the Met Office found that rainfall in England over the past 18 months was the highest since records began, leaving many farmers’ fields underwater. Data from an ADHB farmer survey found that the wheat planting area is down 15% this year. Climate change makes extreme weather events more likely and, while increased temperatures will have an effect on yields, the increase in extreme weather events will mean more variability from one year to the next due to droughts and strong winds affecting harvests. Producing food will become harder and the total amount of food produced globally is expected to reduce. 

The way that climate change is happening also means that larger regions may be affected by extreme weather events at the same time. In 2018, the northern hemisphere experienced a prolonged heatwave, with record temperatures across North America, Europe and Asia. Such events will prevent countries from trading their way out of food shortages as other countries will be affected at the same time. Major shocks are also likely to impact how countries behave, for example the food riots that spread across the world in 2008 were exacerbated by export bans and trade restrictions.

Why is public engagement so important to you and your research?

Citizens are key to transforming the food system, both through their own choices and the influence they can exert when they go to the supermarket. We need people to make more climate friendly food choices but food is deeply personal, and there’s a wide range of factors which determine these choices. 

Policymakers have an important part to play but understandably there’s a lot of resistance from the public to policies which affect what they can eat. That makes intervention by policy makers politically toxic. As Jean-Claude Juncker, former president of the European Commission, put it: “We all know what to do, but we don't know how to get re-elected once we have done it."

We need to get across the message that food impacts climate change, and that small changes like eating more plants can make a big impact. That will help make the public more receptive to policies in this area in the future. In 2018 we saw the introduction of the sugary drinks tax, that tax would never have been introduced if there hadn’t been widespread public acceptance that sugar is causing a health crisis. 

We need a national conversation about how to change the food system. We have to reduce the emissions it produces and make it more resilient to future extreme weather. 

What do you think needs to happen to create a more resilient food system for the future?

We have an excellent plan, the National Food Strategy written by Henry Dimbleby, which was commissioned by the Government and came out in 2020. We also need joined-up thinking on food across Government: at the moment food is spread across multiple departments. We need Government agencies and businesses to explore and fund options to make the food system more robust to shocks. That includes restoring degraded soils and biodiversity and improving working conditions within the food supply chain and ensuring fair pay for food producers. Currently 90% of profits in the food system occur beyond the farm gate. We also need to grow more robust crop varieties and species, use resources more efficiently, and establish backup storage and distribution systems to move away from our reliance on just-in-time delivery.

What do you love about the climate change work you do now?

Climate change is the most pressing issue the world faces right now so to me it feels like this is the most important thing I could work on. I love that food is something that everyone cares about, and so it's something that you can talk with anybody about, whatever age, whatever their background or experience.

I’ve also always been fascinated to figure out what’s best to eat from a nutrition and health point of view - and the connection between climate and food makes this an even more interesting challenge. Talking to people to understand their preferences and constraints and bring all those things together - that’s exciting when we come up with something they feel good about and want to try out. 

Then we have the challenge of making change happen on a bigger scale. How do we change the system? How do we factor in the real lives of food producers and citizens in working out a good way forward? And how can individuals help get those changes to happen?

Are you hopeful we can make a more resilient food system?

I am, but I think it’s going to get worse before it gets better. There are more extreme weather events on the horizon and I think we’ll see a lot of disagreement before we come up with some solutions. 

My recent research looks at the possibility of the UK facing food shortages in the future and whether those shortages could cause civil unrest, which 40% of food experts we spoke to thought was possible or more likely than not in the next ten years. 

However, there are lots of changes that can be made to fix the food system - the problem is not a lack of technology but a lack of agreement about what to do. Change is always scary so we need to make sure the mechanisms are in place to support that change and the people whose lives and livelihoods are directly affected. 

I’m hopeful that we can make that change, that we can reduce the environmental impact of our food and create a system that’s more resilient. That will mean a safer world for the future.

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