How warm the whole planet and its oceans are compared with normal, from four agencies. It is background: El Nino adds to it for a few months.
Indices
This group gathers the global temperature records:
ERA5 (Copernicus Climate Pulse): daily global air temperature at 2 m and daily sea surface temperature between 60 S and 60 N, with anomalies from 1991-2020 (Global air temperature, daily (ERA5), Global sea surface temperature, daily (ERA5, 60S-60N)).
Met Office HadCRUT5 / HadSST4: monthly global land + sea, global sea and tropical sea anomalies, from 1961-1990 (Met Office global and tropical anomalies).
NASA GISTEMP: monthly global and yearly tropical anomalies, from 1951-1980 (GISTEMP global and tropical anomaly).
NOAA NCEI: monthly global and Asian land anomalies, from 1901-2000 (NOAA global and Asia monthly anomalies).
How to read it
Values are anomalies in °C: the difference from each agency's own baseline period. An older baseline gives a bigger number for the same year, so compare the shapes of the lines, not the values across agencies.
Daily ERA5 values arrive 2-3 days late; the monthly records about 1-6 weeks after the month ends.
Why it matters for Koh Samui
A strong El Nino usually lifts the global mean by roughly 0.1-0.2 °C a few months after its peak, on top of the long warming trend. It explains why records can fall in 2027 and why the sea around Samui runs warm (coral bleaching risk).