Second hottest March on record - NASA global temperature update with year to date comparison

According to GISS NASA, the average global surface temperature anomaly for March was 1.12 °C, which is 0.16 °C lower than the hottest March in 2016, making March 2017 the second hottest March in the record.

Here is a chart of the average of 12 months to March each year. The 12 months to March 2017 averaged 0.93 °C above the 1951-1980 mean and was almost identical to the 12 months to March 2016, being just 0.02 °C cooler. This makes it the second hottest April to March 12 month period on record.

Figure 1 | Global mean surface temperature anomaly for the 12 months to March each year. The base period is 1951-1980. Data source: GISS NASA

Below is a chart of the month of March only. This March was 1.12 °C above the 1951-1980 average and was the second hottest March on record. It was 0.16 °C cooler than March 2016 but 0.2 °C warmer than the third hottest, which was 0.92 °C back in 2010. Hover over the chart to see the anomaly in any March:

Figure 2 | Global mean surface temperature anomaly for the the month of March only. The base period is 1951-1980. Data source: GISS NASA

ENSO year comparisons - another El Niño?

There was no La Niña after the recent El Niño, or not according to the Australian Bureau of Meteorology (by NOAA criteria there was a weak one). In the chart below you can see the global mean temperature trend by month. It shows the strongest El Niño years since 1950, which were followed by a La Nina. I've included the 2015-17 period for comparison. The BoM ENSO update is now showing neutral, with a 50% chance of an El Nino later this year.

Of the seven very strong, strong and strong to moderate El Ninos since 1950, there were only three that were followed by a La Nina (not including 2015-17, which I don't count). The chart spans a three year period. That is, for the 2015-16 El Niño and subsequent, it goes from January 2015 to December 2017, or would if the data allowed. (For a more detailed explanation see the HW articles: El Niño to La Niña years with more detail here.)

Figure 3 | Global mean surface temperature for strong or moderate/strong El Nino years that were followed by a La Nina. Also includes the 2015/16 El Nino for comparison. Data source: GISS NASA

Looking at the chart above for 2015-17, you can see that if there was a La Niña, it wasn't just very weak, it was also very hot. Quite a bit hotter than most previous El Niño months and way hotter than any past La Niña. You can also see that we may be heading into another El Niño. The Australian Bureau of Meteorology first issued an El Niño Watch in its ENSO wrap-up last month (see the HotWhopper sidebar).

Where was it hot?

Last month it was very hot in the Arctic and all over Europe through to Russia. Actually, it was really warm almost everywhere wasn't it. (It's all about expectations. With global warming continuing...)

Figure 4 | Map showing mean surface temperature, anomalies for March, from the 1951-1980 mean. Source: GISS NASA

Below is the chart for February this year for comparison. In March the heat spread further west over Europe. Parts of Antarctica were hotter, and parts were cooler than in February.

Figure 5 | Map showing mean surface temperature, anomalies for February, from the 1951-1980 mean. Source: GISS NASA

The chart below will give you an idea of just how hot it was in different latitudes last month.

Figure 6 | Global mean surface temperature anomaly by latitude for March 2017. The base period is 1951-1980. Data source: GISS NASA

Year to date chart (already)

For the record, here for the first time this year is the year to date progressive chart. You need to understand what it is to make sense of it. What the chart below shows is the average temperature for the year at each point on each separate line on the chart. The topmost line is last year (2016). At January, the point is just the anomaly for January. At February, the point is the average anomaly for January and February. At March, it's the average of January to March inclusive - all the way to December, which is the average for the whole year.

So the 2017 year shows that the average for the period January to March is 1.04 °C. This is 0.2 °C lower than the average for the year was this time last year during the massive El Nino. The average over the entire 2016 year is 0.98 °C (the point marked for December on the 2016 line) so this year could be on track to be another hottest year.

Figure 7 | Global mean surface temperature anomaly average year to date (progressive), by year - up to March 2017. The base period is 1951-1980. Data source: GISS NASA

The anomalies for the rest of the year would have to remain high for 2017 to be hotter overall than last year, an average of 0.96 °C. What we thought a year ago would be impossible is not beyond the realms of possibility after all.