UN chief Antonio Guterres warns that humanity faces an "existential crisis" caused by the rapacious destruction of life-sustaining nature. "Every year, we see temperatures climbing higher. Every day, we lose more species. Every minute, we dump a garbage truck of plastic waste into our oceans, rivers and lakes. Make no mistake. This is what an existential crisis looks like," the secretary-general tells delegates to the UN's COP16 biodiversity summit in Cali, Colombia. SOUNDBITE