Delegates from nearly 200 countries are in the South American nation of Colombia for two weeks of discussions with a critical focus: our planet's future. They're at the largest United Nations biodiversity conference in history. (Biodiversity, the bedrock of life on earth, refers to the variety of animals, plants, fungi and even bacteria that make up our natural world.) Globally, biodiversity is declining faster than at any time in human history, scientists say. The main causes include climate change, commercial overfishing and loss of habitat as development shrinks forests, fields, waterways and even some jungles.

The impact of losing bird, fish, mammal and plant species affects food supplies. Reducing their natural habitats has related effects on people. "When we destroy biodiversity, we are destroying the very links that help the system to reproduce life," says Environmental Minister Susana Muhamad of Colombia, who is presiding over the conference that began last week in Cali, her country's third-largest city. "Nature is not a resource, it is the fiber of life that makes us ourselves possible," she added.

International cooperation is needed to tackle biodiversity loss and climate change, so the gathering's general goal is an agreement on investments to protect ecosystems and to strengthen environmental policies. "For humanity to survive, nature must flourish," UN Secretary General António Guterres said at the opening session. Specific objectives include halting extinctions, reducing pollution, preserving areas with high biodiversity importance and keeping wild species from being overharvested. The United States hasn't yet ratified a 2022 biodiversity treaty with those pledges, signed by 196 other countries. Several dozen people from the U.S. State Department and other agencies are at the Colombia event.

How biodiversity helps us: Healthy rivers and oceans run with fish we need for food. Insects nourish soil and pollinate plants. Birds and mammals disperse seeds. Plants turn sunshine into food.

Environmentalist says: "There is a worrying gap between what was promised in Montreal [two years ago] and the plans put in place so far to reverse the loss of nature by 2030." -- Bernadette Fischler Hooper of the World Wide Fund for Nature, based in Switzerland

Big hurdle: Countries that are richest in biodiversity tend to have less money to spend on protecting it.