Modern agricultural systems have achieved astounding gains in productivity in the past 50 years, but they have come at an enormous cost to nature. Farming is responsible for around a quarter of emissions warping the climate. It's also one of the primary drivers of biodiversity loss, responsible for threats to 80% of at-risk species.
Crop and livestock farming is estimated to occupy some 50% of the world's habitable land. While ecosystems such as the Amazon, where cattle farmers are clearing rainforest, usually dominate the headlines, important native grasslands in countries like the US are also being plowed up for crops such as wheat. Intensive livestock farming has the greatest impact on species loss, because of its high emissions, water pollution and the amount of food needed to feed the animals.
Since the 1940s, giant monocultures have dominated farming, largely replacing small farms that grow multiple crops. The effects on biodiversity have been devastating, said pollination ecologist Barbara Gemmill-Herren.
"With large-scale monoculture, after a while, it just becomes a sort of a desert for biodiversity," said Gemmill-Herren, who is a senior associate at the World Agroforestry Center, an international institute in Nairobi, Kenya. "Intensive farming of any sort, it's just inimical to the insects that really need to thrive, and along with insects comes everything else," said Gemmill-Herren.
Bees and other pollinators — a key indicator of broader biodiversity — struggle to service such vast areas of monoculture. These single-crop farms lack other animal and plant species that combat the spread of diseases and pests. That in turn intensifies use of pesticide, herbicide and fertilizer, which can pollute rivers and streams, and damage the soil, as well as the insects and worms that birds feed on.
Pesticides are a heavy fist that are overused and poorly targeted, according to Gemmill-Herren. Fertilizer overuse is damaging biodiversity. Run-off into water systems leads to excess nutrient content that causes bursts of algae growth, which then block sunlight and suck oxygen out of the water as they decay, killing aquatic life.
A classic example of this in the US is the Mississippi Delta where a dead zone threatens one of the country's most important fisheries.
"For many biodiversity challenges it's pretty clear what the solutions are," Stephen Wood, an agricultural and food systems scientist with The Nature Conservancy and Yale University in the United States, said. "If we want to restore ground nesting birds, we need to create habitats for ground nesting birds or if we want to create habitats for migrating sandhill cranes in in the US, we need to maintain flooded fields and make sure that there is adequate corn or rice grain left on the ground for them to use as a food source."
It's just a matter of building a system that encourages these practises, added Wood.