NASA
The astronomer Carl Sagan famously described Earth as a pale blue dot when viewed from far away. Tiny and insignificant it may look, but this blue dot has provided us with a remarkably stable environment for almost 12,000 years.
As we have multiplied, we have pushed Earth close to – and possibly beyond – its ability to support human society. On several fronts, we have exceeded what scientists regard as “limits” for some of Earth’s most vital life support systems, such as the nitrogen and phosphorus cycles and biodiversity.
On other fronts, we are fast approaching the danger zone. Climate change is the most pressing, not least because it has the ability to drive Earth into a new state that’s inconsistent with our well-being. To stay safe, we need to limit warming to 2°C – and preferably 1.5°C – above