2017 hottest year adjusting for ENSO

2017 was marginally cooler than 2016, which was an El Niño* year.  The fall from 2016 was much less than the decline after the last El Niño in 1998**.  The chart below shows the temperature record adjusted for El Niños.  Adjusting for the impact of El Niños, 2017 was the hottest year.  Note how major volcanic eruptions cause temperatures to drop for a couple of years.  This is because eruptions release particulates (mostly sulphur dioxide) into high altitudes, which reflect incoming solar radiation.  If you fitted a long-term moving trend to the data from 1950 onwards you would get a steadily rising curve:  the rate of increase in temperatures appears to be accelerating.

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* ENSO stands for El Niño Southern Oscillation

** a favourite start year for denialists wanting to "prove" that temperatures haven't risen over the last X years.