At the risk of repeating myself, I’ll repeat myself. Global temperature is a combination of trend and fluctuation.
The fluctuations make it jitter about from year to year (or month to month, or day to day, or whatever), but the trend of late has been steadily upward. It’s called global warming (although some might prefer “global un-cooling”). We even know some (but not all!) of the causes of the fluctuations; things like the el Niño southern oscillation (ENSO), massive volcanic eruptions, and variations in the output of the sun itself. But the fluctuations don’t last. The trend, however, continues upward unabated.
Earth’s hottest year on record remains 2016, when the warming from man-made climate change combined with extra heat from the strong el Niño of that year. But even without el Niño, this year is likely to come in a strong 2nd. Here are yearly averages since 1950 from NASA, with the 2019 value year-to-date (January through October):
I regularly estimate the impact of things like el Niño, volcanic eruptions, and solar variations on global temperature. Then I can remove those temporary influences for a clearer picture of the long-term changes: the global warming. I did this with the latest NASA data, and here they are plotted as red triangles (un-adjusted data still as blue x’s):
Interestingly, while the raw-data 2019 value will probably come in 2nd, the adjusted-data 2019 value will overtake 1st place.
NOAA data tell a slightly different story. The raw data (blue x’s) have 2019-so-far in 2nd place (just barely beating 3rd place), and the adjusted data (red triangles) have 2019-so-far also in 2nd place (just barely failing to beat 1st place).
Turning to the data from HadCRU (the Hadley Centre/Climate Research Unit in the U.K.), we find that 2019-so-far only makes it to 3rd place, behind 2016 and 2015, but when adjusted it takes over 1st place:
A modified version of the HadCRU data is from Cowtan & Way, which, like NASA, has 2019-so-far in 2nd place and adjusted-2019-so-far in 1st place:
Finally, the global estimate from the Berkeley Earth Surface Temperature project imitates NASA and Cowtan & Way, with 2019-so-far in 2nd place, adjusted-2019-so-far in 1st place:
Four of the five data sets have 2019 coming in 2nd place, only HadCRU has it 3rd. Four of the five adjusted data sets have 2019 coming in 1st, only NOAA puts it second.
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