[engineer_22]

https://climatereanalyzer.org/research_tools/monthly_tseries...

What changed in 1979?

[Windchaser]

Probably just an El Nino / La Nina oscillation. Looks similar to the changes leading up to 1998 (another big El Nino), 2016 (same), and 2024.

More glibly: "the temperature"

[engineer_22]

Haha, actually the long term trend changed abruptly

[interloxia]

I don't know but it cooencideds with the start of satellite monitoring.

Half a century of satellite remote sensing of sea-surface temperature (2019) https://www.sciencedirect.com/science/article/pii/S003442571...

I haven't looked but there will probably be references somewhere explaining the dat sources.