Excessive chemical use decks biodiversity.

Most species cannot survive and reproduce in agricultural land20, meaning this transformation has resulted in rapid population decreases for thousands of species across the world21 and 22 and is a major cause of extinction risks: almost 90% of the critically endangered mammal species, and more than 80% and 70% of the critically endangered amphibian and bird species, respectively, are unable to live in agricultural lands and have thus been greatly impacted. Harm is particularly severe for species with narrow ranges and specialized habitat requirements23, and for large-bodied species24.

South and Southeast Asia are home to the greatest regional diversity of large mammals (155 species) but rapid agricultural expansion, economic growth and hunting pressures over the last 60 years have resulted in ~60% of these being threatened with extinction25 and 26. Current food system trajectories could push many of these mammals toward global extinction27. In Sub-Saharan Africa only 30% of large mammals are threatened, but current food system trajectories could elevate these to extinction risks that exceed those currently observed in South and Southeast Asia. Similarly, large mammals of tropical South America could attain extinction risks in 50 years like those of present-day South and Southeast Asia28.

The global agricultural land conversion that has occurred to date has fragmented natural habitats, separating remaining patches with farmland, fences, roads and other structures29 and 30. The resulting smaller, isolated populations are much more vulnerable to extinction31, 32 and 33; many species still surviving in fragments may be on deterministic trajectories toward extinction34 and 35. Because this ‘extinction debt’ in fragmented landscapes may take decades or centuries to result in extinction, the threats posed by fragmentation may not be immediately obvious. However, a range of empirical studies, including a major synthesis36, have demonstrated that heavily fragmented landscapes and habitats lose large numbers of species over time, with smaller fragments and those separated by greater distances losing species more rapidly. Preserving remaining large blocks of intact habitats is vital for biodiversity conservation.

Agricultural land management is increasingly intensive, with nitrogen fertilizer and pesticide use now ~6 and 12 fold greater, respectively, than at the advent of the Green Revolution in 196137 and 38. This intensification has increased yields in many regions and so reduced demand for additional cropland and helped preserve some natural habitats39, 40 and 41. However, intensification can reduce habitat suitability for species that could otherwise survive in farmland42 and has resulted in widespread declines in farmland biodiversity43. The resulting fertilizer and pesticide pollution threaten many marine and freshwater species with extinction44 and 45. Agriculture’s greenhouse gas emissions, 30% of the global total, which are caused by excess nitrogen fertilization, ruminants and land clearing, also threaten both biodiversity46 and agricultural and fishery productivity47.