Positive tipping points are thresholds in Earth systems where a small change makes a big difference. (Image credit: Rebecca L. Latson via Getty Images) Research suggests we are on the brink of crossing several ecological "tipping points" that could derail ecosystems like the Amazon rainforest and permafrost-covered tundras. But just as humans can cause these negative tipping points, we can also trigger positive ones that restore ecosystems, says Tim Lenton , a professor of climate change and Earth system science at the University of Exeter in the U.K. In a new perspective article, Lenton argues that positive tipping points are key to hitting targets enshrined in various biodiversity and ecological restoration frameworks, including the United Nations Decade on Ecosystem Restoration 2021-2030 . Examples of these targets include restoring 30% of all degraded ecosystems and conserving 30% of land and water by 2030.…