Short answers, pulled from the story.
A climate tipping point is a critical threshold in the climate system that, when crossed, leads to large, accelerating, and often irreversible change. The danger lies in self-reinforcing feedbacks: once a tipping point is crossed, the system drives its own change and may not return to its initial state even if the original cause of warming is reduced.
As of September 2022, scientists had identified nine global core tipping elements and seven regional impact tipping elements in the climate system. Of those, one regional and three global elements are estimated to likely cross a tipping point if global warming reaches 1.5 degrees Celsius: the Greenland ice sheet collapse, the West Antarctic ice sheet collapse, tropical coral reef die-off, and boreal permafrost abrupt thaw.
A complete melt of the Greenland ice sheet would raise global sea levels by 7.2 metres. The ice sheet is currently melting at an accelerating rate and adding almost 1 millimetre to global sea levels every year. Its tipping point is driven by the melt-elevation feedback, and while the tipping point can be crossed at relatively low warming levels, the full melt would unfold over millennia.
Cascading tipping points occur when crossing a threshold in one part of the climate system triggers another tipping element to shift into a new state. A 2021 study using three million computer simulations found that nearly one-third resulted in domino effects even at warming below 2 degrees Celsius. Temporary overshoots of climate targets can increase the risk of such cascades by up to 72% compared with non-overshoot scenarios.
Research published in Nature by Wunderling and colleagues found that a near system-wide transition across 62-77% of the Amazon could be triggered by combining warming of 1.5-1.9 degrees Celsius with 22-28% deforestation. Between 17% and 18% of the Amazon has already been cleared, placing the system close to that combined threshold.
The Atlantic Meridional Overturning Circulation (AMOC), also known as the Gulf Stream System, is a large system of ocean currents that transports warm water northward and returns cold water southward. If it collapses, parts of Europe could experience cooling of more than 10 degrees Celsius, sea levels in the North Atlantic could rise by around 1 metre, and crop yields would likely fall across most world regions. An August 2025 study concluded that AMOC collapse could begin as early as the 2060s.