Globally, agriculture is the greatest threat to biodiversity and a major contributor to anthropogenic greenhouse gas emissions. How we choose to deal with rising human food demand will to a large degree determine the state of biodiversity and the wider environment in the 21st century. My talk focuses on two contrasting supply-side approaches to this challenge: land sharing, in which farmland is made as friendly to wildlife as possible, albeit at the cost of lower yields; and land sparing, in which space for nature on unfarmed land is maximised by farming elsewhere at high yields. Developing and then parameterising a simple model of the population-level impacts of these alternative approaches shows that across five continents, many biomes, and almost 2000 species ranging from birds to sedges, a land-sparing approach consistently outperforms land sharing, particularly for species of highest conservation concern. These findings raise further important questions – about other consequences of high- vs lower-yield farming, how to increase yields while lowering environmental externalities, and how to tie yield increases to setting aside land for nature - but they also suggest it might be possible to feed 9 billion people while safeguarding much of wild nature.

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About the speaker

Andrew is Professor of Conservation Science and a Royal Society Wolfson Research Merit Award holder at the Department of Zoology, University of Cambridge, and is on sabbatical at University of Tasmania until December 2018. His main research interests are exploring how conservation might best be reconciled with land-demanding activities such as farming, quantifying the costs and benefits of effective conservation, and examining what works in conservation. In his book Wild Hope he argues that cautious optimism is essential in tackling environmental challenges. Andrew helped establish the Student Conference on Conservation Science, the Cambridge Conservation Initiative and Earth Optimism.