(CNN) A drop in global biodiversity is putting our ability to produce food at risk, a new United Nations report warns.

However, in recent years biodiversity at the genetic, species and ecosystem levels have all been in decline, reducing our overall food and agriculture systems' ability to respond to shocks and stresses such as climate change.

"Many key components of biodiversity for food and agriculture at genetic, species and ecosystem levels are in decline," the report said. "The proportion of livestock breeds at risk of extinction is increasing. Overall, the diversity of crops present in farmers' fields has declined and threats to crop diversity are increasing."

At the species level, many of those serving vital functions such as pollination or pest management are in decline "as a consequence of the destruction and degradation of habitats, overexploitation, pollution and other threats."