After reading the article more careful, it seems that it is about the cooling of the Atlantic near the equator. I understand that articles on site like the New Scientist do not include links to the original scientific reports or data, but at most links to the people they are quoting. This makes it difficult to verify the statements or to even precisely understand what it is about. The Atlantic is a large ocean reaching from almost the arctic to antarctic, an averages of some parts of it could only have a weak correlation with each other even if they are partly overlapping.

search by primary author, often works.

in this case the subject matter “Atlantic Niña”

elicits:

https://www.climate.gov/news-features/event-tracker/atlantic...

https://www.aoml.noaa.gov/atlantic-nina-on-the-verge-of-deve...

I guess you have to wait for the article in The Atlantic.

https://www.theatlantic.com/science/archive/2024/04/dubai-om...

I don't' think the article is focused on the temperature itself but rather the rate of change. During the time period referenced the speed of temperature change was fastest.

The derivative is the topic.

This is good to note. The New Scientist article is really talking about the rate of cooling, not the extent of cooling.

This. The point of interest should had been why it warmed up so fast before, not why it falling down now to a bit closer to what used to be normal. Specially if we are talking about limited regions of the ocean (not the whole ocean), with water circulation playing a role there.