According to the Living Planet Index, a metric that’s been in existence for five decades, animal populations across the world shrunk by an average of 69% between 1970 and 2018. Not all animal populations dwindled, and some parts of the world saw more drastic changes than others. But experts say the steep loss of biodiversity is a stark and worrying sign of what’s to come for the natural world. “The message is clear and the lights are flashing red,” said WWF International Director General Marco Lambertini. According to the report’s authors, the main cause of biodiversity loss is land-use changes driven by human activity, such as infrastructure development, energy production and deforestation. But the report suggests that climate change — which is already unleashing wide-ranging effects on plant and animal species globally — could become the leading cause of biodiversity loss if rising temperatures aren’t limited to 1.5C.