The effects of climate change usually take decades and centuries to manifest, but this summer they seem to be everywhere: temperature records are constantly being broken, ocean waters are as warm as whirlpools, and world leaders are so concerned they've called it the "global boiling point era."

And as concerning as these developments are, scientists have long feared even more dramatic, imminent, and irreversible changes to the planet that could happen quickly. Even in the past year, there has been evidence that some of these scenarios are increasingly likely.

Article in in the journal Science in 2022 addressed several climate "tipping points" – conditions beyond which changes become self-perpetuating and are difficult or impossible to reverse. While the concept has raised concerns from some scientists who have argued that it is overly simplistic, the paper suggested that even the possibility of such points of no return provided compelling reasons to limit warming as much as possible.

About a year later several global systems that have worried scientists, are showing signs of increasing fragility. (ELIZABETH WEISE )