We know that biodiversity is declining due to human activities and climate change. It’s estimated that we will lose half to one million species in the coming decades. But what does this mean for our ability to feed the global population and what do we need to do about it now?
“Efficiency gains in agriculture, albeit indispensable, will not be enough to achieve food security under severe climate change. Pathways to eradicate global hunger, while bending the curve of biodiversity loss, unanimously suggest changing to less energy-rich diets; closing yield gaps through agroecological principles; adopting modern breeding technologies to foster stress resilience and yields; as well as minimising harvest losses and food waste,” said Ralf Seppelt of the Helmholtz Centre for Environmental Research.
“Throughout environmental history, humanity has prospered from the natural resources provided by biodiversity,” he explained. “At the same time, humans shape(d) their environments and the biodiversity it’s hosting. While the mutual feedback between biodiversity and human well–being is undisputed, it has received remarkably little analytical treatment. I hope to convincingly propose how to bridge the research fields of ecology and agroeconomics that make the trade-off between food security and protection of biodiversity explicit, which is the core of my STIAS project.”
Seppelt started his presentation by showing two photos – the first of allotment gardens where he is based in Leipzig, first established in 1865. “The idea was to give children a healthy and close-to-nature environment to play in. You could grow all the food, have small animals and a playground. But space is limited,” he said.
He also showed the famous 1972 Apollo 17 ‘Blue Marble’ photo of the Earth which inspired the early environmental movement and the global summits on climate which questioned how to protect Earth and its space limitations.
It’s hard to accurately measure the amount of land currently used for agriculture globally – the United Nations Food and Agriculture Organization puts it at just under 40% of the global land surface with about two-thirds of this used for grazing livestock and one-third for crops. And what do those crops comprise? Seppelt pointed out that the most planted crops are wheat, maize and soya; those with the greatest biomass are sugar beets and sugarcane; but the most lucrative crops are cannabis, cocoa and poppy.
“In the last 60 to 80 years – increasing population has meant increasing production per capita and increasing use of fertiliser. Production has surpassed population growth.”
“We can feed the world,” he continued, “but about 220 million kids below the age of five are malnourished with huge divisions between the Global North and South in terms of overweight versus wasting, and obesity as big a problem as malnutrition.”
“Planet space is limited. Production increases won’t continue and we will reach saturation point. We are in the peak years of some renewable resource production. Food produced by increased fertiliser use means we spend more energy.”
Seppelt also noted that it’s hard to assess the global biomass index. Humans comprise 34% of global mammals but wild mammals are only 4% of the total. This means 96% of global mammal biomass is managed by humans.
“And how many species are there? It’s estimated that there are around 8 million species on the planet but only 2.16 million are well described.”
Gathering the evidence
Data and thus reliable evidence are hard to come by especially data that bridges disciplinary divides. Seppelt therefore briefly outlined the extensive processes undertaken by the Intergovernmental Platform for Biodiversity and Ecosystem Services (IPBES), of which he is part. He did so by reporting on its 2019 Global Assessment Report on Biodiversity and Ecosystem Services.
He explained that IPBES is about bringing together scientific knowledge that is policy-relevant but not policy-prescriptive. He provided an overview of how an assessment is conducted, how review processes work and how the final documents are negotiated.
“Tracking the evidence between biodiversity and yields in agricultural landscapes is providing the evidence that biodiversity is going down under conventional intensification,” he said. “Some of the more significant results of the assessment included that 75% of global land has been significantly altered and 66% of the sea is experiencing cumulative effects of change. The drivers include social, cultural, economic and institutional/governance factors.
However, the overall message of the report is that a sustainable economy needs to move away from the limited paradigm of economic growth.
From his work, Seppelt also reported on an example of scientific synthesis using meta-analytic approaches. The work started with the screening of almost 10.000 papers leading to a meta-analysis of 115 studies.
He noted that looking at the simultaneous effect of land-use intensity on diversity and yield at the same location showed the value of small intensification steps – meaning that we can achieve a lot in protecting biodiversity and yield with moderate agricultural intensification. “Land management negatively influences biodiversity but biodiversity also positively influences agricultural production with a medium level of intensity seeming to be most optimal,” he said. But, he also warned that the complexity is still underestimated.
Modelling biodiversity and optimum resource use
Seppelt’s work at STIAS will therefore look in detail at how diversity sustains societies’ resilience, asking: How does incorporating biodiversity change solutions of optimum resource-use problems?
The project aims to develop novel modelling approaches that deepen our understanding of the role of diversity of biological components, natural resources and societal aspects to test various hypotheses on the stability of socio–environmental systems. Seppelt will use innovative biophysical and socio–economic models to develop biophysical principles–based models incorporating the interactions of biodiversity–production mutualism.
Climate change
Seppelt also discussed the continuing impact of global warming on the food system. He noted that generally warmer equals quicker growth and more CO2 in the atmosphere is good for plants but this will be overrun by extreme weather events.
“A moderate gain in the area suitable for agriculture is confronted with substantial yield losses through strains on crop physiology, multitrophic interactions, and more frequent extreme events. Self-amplifying feedbacks are unresolved and might lead to further losses.”
Doable solutions
“There will be adaptation, specific crops will adapt but we need a broader range of growth,” he added.
“Most important is that we are wasting lots of energy on a meat-based diet,” he continued. “Change would free resources and make the landscape more diverse. We don’t all have to be vegetarian, but we should all reduce meat consumption – red meat especially.”
He also pointed to the need to bring disciplines together (especially agronomy and ecology which “don’t talk to each other”); to further understand the impact and role of smallholder farming which needs much more data and attention; and, the urgent need to make politicians and scientists talk to each other.
“No further research is needed to know what to do. We can feed everybody,” he said. “The solutions are doable. We just have to take action.”
“In the last 60 years, child mortality has decreased, education and health have improved, and humans have even invented renewable energy sources – a little late but still with sufficient time to switch. But more is needed to turn the corner.”
Michelle Galloway: Part-time media officer at STIAS
Photograph: Ignus Dreyer