The activity uses the annual global land-and-ocean series from NASA GISTEMP version 4. Its reference period is 1951–1980. Our trailing five- or ten-year averages are calculated from the displayed annual values. They are labelled Nepedia calculations and are not the LOWESS curve shown in some NASA graphics.
Weather and climate · Discover & try
How can a warming trend contain cooler years?
Reading level 3 of 5 · IndependentChange
Word help
Anomaly
A difference from a specified reference average.
Trend
A persistent pattern across an interval, which may contain shorter fluctuations.
Running average
An average recalculated over successive groups of observations.
Watch · Try · Explain
See how it works
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Actual NASA GISTEMP v4 annual anomalies, 1980–2024; optional trailing averages are Nepedia calculations, not forecasts.
What to look for
- Read the 1951–1980 reference period.
- Compare annual dips with the multi-decade record.
- Distinguish our trailing mean from NASA LOWESS.
Explain what you noticed
A different 40-year record rises overall but its last year is cooler than the previous year. What follows?
Keep this idea: Year-to-year variation and a multi-decade trend describe different time scales.
Follow the sources
Source material checked 2026-10-28. Explanations and activities by Nepedia. Source links do not imply endorsement.
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