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Climate, Environment

El Niño–Southern Oscillation and Global Warming: 2020 Update

The headline: The ENSO year2019–2020 was the second hottest year on record.

The ENSO cycle typically does not follow a calendar year, with El Niño and La Niña cycles often starting around late spring or early summer in the northern hemisphere. Consequently, ENSO years can be viewed as a more appropriate approach to understanding ENSO events and global warming.

The El Niño–Southern Oscillation (ENSO) year 2019–2020 (i.e., July 2019 to June 2020) was the second hottest on record. The previous five ENSO years were the five hottest on record. Since 1950, the global warming rate is 1.41 °C/100 years (it was 1.37 °C/100 years in the 2018 update; http://chartedterritory.us/2018/08/17/el-nino-southern-oscillation-and-global-warming-a-2018-update/). El Niño (1.38 °C/100 years), Neutral (1.23 °C/100 years), and La Niña (1.58 °C/100 years) years are all demonstrating significant warming trends. The last two La Niña years were above the post-1950 El Niño trend line.

The chart: Annual temperature anomalies since 1950. Each circle represents an annual temperature and is colored according to whether it was an El Niño event (red), La Niña event (blue), or a neutral year (grey). The size of each red and blue circle is proportional to the intensity of the El Niño/La Niña event ranging from weak (small), through moderate and strong, to very strong (large). The trend line (dotted lines) and r-squared values are reported for each set of events (i.e., El Niño, La Niña, and neutral years).

The data: Global temperatures and El Niño–Southern Oscillation (ENSO) data are sourced from NOAA1,2. Monthly ENSO data are publicly available from NOAA since 1950 (annual data, on a calendar year basis, are available back to 1900). The data were compiled and visualized by Charted Territory.


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