Global temperature in May 2020 set a record
for May (1.29°C, relative to 1880-1920) for the period of adequate data,
i.e., since 1880. That is the third monthly record in the first five
months of 2020, despite the fact that temperatures this year are not
boosted by a strong El Nino.
2020 and 2016 will be the two warmest years, but which one will wear the
crown? The answer is of little import – they will be close, likely a
statistical dead heat – but in this Covid-19 year we need to have a
little fun, and we can set the stage to learn something from the result.
2020 is a bit cooler than 2016 so far (graph above), but 2020 could pass
2016 to become the warmest year, because late 2016 was cooled by a La
Niña (see May Update and graph above).
However, we suggested caution
about confident predictions that 2020 would be the warmest year,
because there is evidence that 2020 is also headed into a La Niña.
Below, global temperature fluctuations are compared with temperature in
the Niño3.4 region in the tropical Pacific. These temperatures are
detrended to take out long-term warming. The correlation of the two
curves is over 60 percent – it would be still higher without the global
cooling effect of aerosols after the 1991 Pinatubo volcanic eruption.
This shows that ENSO (El Niño Southern Oscillation) strongly controls
short-term global temperature fluctuations. Lag of the detrended global
temperature anomaly behind the Niño anomaly averages 4.5 months.
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