The two NASA graphs below, both published in 2020, look entirely different because the top graph was drawn with a broken Y axis which started at 14 C instead of zero. The second below, a bar graph, published only once in 2020, was drawn correctly with a zero Y axis. However, the baseline previously published at 15 C was reduced to 14 C in 1995. There was no need to alter the graph itself, the anomalies could remain the same all they had to do was lower the original  baseline temperature from 15 C to 14 C. The temperature in 2020 measured at 1.02 C above the 14 C baseline is now 15.02 C instead of 16.02 C had the previos baseline of 15 C been retained. The WMO published baseline periods of 1951-1980 for 1994 and 1961-1990 for 1995 but not temperatures.

NASA Original Graph With 15 Degree Baseline

The 1994 temperature was calculated at 15.32 C using the original baseline of 15 C degrees (59 F) which  matched the 15.31 C temperature recorded some thirty years later by the WMO in 2024 who used the same anomaly but a different baseline of 14 C (57 F), posted by CRU East Anglia Hockey Stick team in 1998.

Excerpts below from New York Times 1998:

The earth’s average surface temperature in 1998 is the highest by far since people first began to measure it with thermometers in the mid-19th century, the World Meteorological Organization reported yesterday. 

According to the new figures, the average global temperature this year will turn out to be about 58 degrees, a full degree warmer than the 1961-1990 average.

”This number’s amazing,” said Dr. Philip D. Jones, a climatologist at the University of East Anglia in England, speaking of a field in which records are normally set in fractions. Dr. Jones provided much of the information on which yesterday’s announcement was based.