Global warming. Disappearing plant and animal species. Fertile land turning to desert. Plastic in the oceans, on land, and the air we breathe. These urgent environmental challenges will be in the spotlight over the next few months as the United Nations hosts four major sessions to address key threats to the planet. Biodiversity: First up is a “Conference of the Parties” — a COP — dedicated to biodiversity being held in Cali, Colombia, from October 21 to November 1. These are called every two years to debate how the world can cooperate to better protect the rich variety of plant and animal life in the natural world. The COP16 isn’t expected to break new ground but is more a stocktake of progress since the last summit secured historic assurances for biodiversity. In 2022 in Montreal, nations agreed to place 30 percent of the planet under environmental protection by 2030 in a landmark pact aimed at arresting biodiversity loss and restoring ecosystems to health. In Cali, countries will put forward national strategies to meet this global objective, and observers hope Colombia as host will provide a model for others to follow. WWF has commended the leadership shown so far by Colombia, which hosts close to 10 percent of Earth’s biodiversity, including countless bird, butterfly, and orchid species. Climate: The world’s most important conference on climate change is this year being hosted by Azerbaijan, a former Soviet republic heavily dependent on oil and gas exports, from November 11 to 22. While the last summit in Dubai in 2023 delivered a historic commitment to transition the world away from fossil fuels, supporting poorer countries with climate change will top this year’s agenda. The summit, known as COP29, is expected to land a new agreement on “climate finance”: money from rich nations most responsible for global warming to developing countries vulnerable to climate change. There isn’t an agreed figure yet, or even consensus on where the money should come from, who should receive it, and what form it could take. But developing countries are pushing for much more than the $100 billion pledged in 2009. This was only reached for the first time in full in 2022. “COP29 offers an opportunity to unlock more climate investments from a wider range of public and private sources and to improve the quality of this finance,” said the World Resources Institute, a US think tank.