Climate Change and Biodiversity: Food Security

Baroness Willis of Summertown Excerpts

Thursday 8th September 2022 Lords Chamber

[Baroness Willis of Summertown (CB) (Maiden Speech)]

My Lords, it is a great honour to address this House for the first time. I start by thanking all the staff in the Chamber of your Lordships’ House, as well as my fellow Peers, for the very warm and helpful welcome that I have received. I also commend the noble Baroness, Lady Boycott, for securing this debate.

I started my academic life as a palaeoecologist, which is one of those terms that makes people look very puzzled when I mention it. For the benefit of the Convenor and others who might not know, this is the study of fossil pollen, plant macrofossils and leaves contained in lake sediments over thousands of years, which you can then use to reconstruct vegetational responses to external perturbations such as climate change. This is particularly important for larger organisms, including one of our most important, our trees. If you think about it, the average generation time of most trees is 50 years. You need these longer-term records to understand how trees will respond.

This research was looking predominantly at dead plant parts, but this all changed when I went on secondment to the Royal Botanic Gardens, Kew for five years as its first director of science. Suddenly I was surrounded by this incredible biodiversity of plants. In fact, in a single lunchtime I could see the world in plants. When at Kew, I was responsible for around 360 scientists. Many people do not realise how many scientists there are at Kew. I was also responsible for the incredible collections in the Millennium Seed Bank, the Herbarium and the Fungarium. Since returning to Oxford from Kew, I have held a professorship in biodiversity in the department of biology, and I am also head of one of the oldest colleges in Oxford, St Edmund Hall.

Today’s debate—

“that this House takes note of the impact of climate change and bio-diversity loss on food security”—

therefore links very closely to my current and past roles. In terms of understanding the scale of biodiversity loss, some of the most startling evidence I have ever come across as an academic was when I co-led a team of scientists from all over the world to assess biodiversity trends in the last 50 years. This was as part of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. We examined thousands of records. It was incredibly depressing, because plants, animals, fungi, species, communities and genetic diversity have all declined significantly in the last 50 years. Two main drivers emerged from this biodiversity loss: land-use change and climate change.

But why should we be concerned about the impact of global biodiversity loss on food security? Often when we look at global biodiversity, we think about David Attenborough programmes and beautiful landscapes, but there is actually something much more critical here, which is its impact overall on food security. This is why: of the nearly 420,000 vascular plant species that we know about on the earth to date, just nine supply over 75% of our plant-derived calories in human diets, with wheat, rice and corn alone providing almost half of the world’s calorie intake.

These crops have been selected for decades, if not hundreds of years, for the high yields that we heard about earlier. This has resulted in high yields and the very good-tasting food that we want to eat, to buy and to feed ourselves and livestock, but as a result we have less and less genetic diversity and smaller and smaller species numbers. The loss of that genetic diversity means that in these crops we have lost our resilience to climate change.

A lot of modelling is going on, and it indicates alarmingly that with global warming of even 2 degrees Celsius, there will be a 20% to 40% reduction in cereal grain production, particularly in Asia and Africa but also in the UK. So we urgently need to restore the genetic diversity of our crops or find alternative, more climate-resilient crops, and this is where there is a critical link back to biodiversity.

Work by scientists at Kew and other institutions, notably the Crop Trust, have identified around 320 species of wild relatives of crops and more than 7,000 wild and semi-domesticated plants used by societies all over the world that are not in major production. The vast majority of these crop wild relatives and underutilised plants grow in much more extreme climates than their highly domesticated versions and, crucially, have genes that allow them to do so. They are effectively climate-resilient. We need to breed that kind of resilience back into our crops. This work is already going on. Some notable institutions, including the John Innes Centre in East Anglia, are breeding climate-resilient crops from the crop wild relatives. The species being looked at are rice, durum wheat, legumes and potatoes.

In line with United Nations sustainable development goal 2, we need to be conserving these crop wild relatives and underutilised crops, yet this is where the problem comes in. These wild relatives of crops and underutilised plants grow in the same biodiverse landscapes where we are seeing the most dramatic declines. Biodiversity loss, including of these crop wild relatives and underutilised crops, is removing in many ways our get-out-of-jail card when it comes to creating create climate-resilient crops, and we should be deeply concerned by that.

However, it is not just the impact of climate change and biodiversity above ground that we need to worry about—we have already heard some of this—it is also about the impact below ground and, in particular, the mycorrhizal fungi that are attached to 80% of terrestrial plants across the world. It is a symbiotic relationship, which means that the fungi get food from the plant and in exchange there is a network across the soil that greatly enhances the uptake of nutrients and minerals and water retention by those plants. Many plants, and many of our economic crops, have very specific mycorrhizal assemblages associated with them.

Application of mycorrhizal fungi to crops has already shown that it can increase grain yields by 16% in crops such as corn, rice, sorghum and wheat. There is now clear scientific evidence to show that this is one of the ways forward to get climate-resilient crops. However, increasing atmospheric carbon dioxide, temperature and pH significantly alter the composition of fungi in the soil and affect their ability to function, so I would go as far as to say that the hidden impact below the ground of climate change and biodiversity loss might be even more significant than the impact above ground. Without the right fungi in the soils, some crops will simply not grow.

To conclude, the combination of climate change and biodiversity loss poses an extremely serious risk to global food security and, in particular, to our ability to grow high-yielding, climate-smart crops. I therefore strongly commend this Motion and thank the noble Baroness, Lady Boycott, for bringing this critically important topic to the attention of your Lordships’ House.