If you prefer (breaking the HN title length):
If the anomaly does not stabilize by August — a reasonable expectation based on previous El Niño events — then the world will be in uncharted territory.
My first thought was the shipping/sulfur regulations but they mention that(and that while there isn't enough data yet, it shouldn't be able to have this impact).
My next guess is the whole ocean-as-a-heat-sink thing. The idea that there has been significantly more energy being input into the system than realized but the ocean has been absorbing a lot more of it than we previously knew about, and now it can't any more. It ties in with the unexpected water temps around florida and the unusually high temps around Antarctica, but it's just a random guess from a random guy.
The linked editorial was written by Dr. Gavin Schmidt, a climatologist and director of NASA’s Goddard Institute for Space Studies in New York City. He writes, in part:
"If the anomaly does not stabilize by August [2024] — a reasonable expectation based on previous El Niño events — then the world will be in uncharted territory. It could imply that a warming planet is already fundamentally altering how the climate system operates, much sooner than scientists had anticipated."
https://en.wikipedia.org/wiki/Clathrate_gun_hypothesis
Somewhat related, I saw a Netflix documentary (can't remember the name of it) a few years back about these researchers in the Bahamas studying blue holes. Some of their findings indicate that every worldwide coral bleaching event in history was followed shortly after with a mass extinction.