Will El Niño re-emerge?
European climate trackers say that April extended a stretch of exceptionally warm global weather going back to mid-2015. The warmth peaked in February 2016 at the height of Pacific Ocean El Niño, then gradually dropped off through June. But in July and August 2016 global temperatures surged upward once again and have stayed high since, according to the latest update from the Copernicus Climate Change Service.
February and March 2017 were the most anomalous months since April 2016. April 2017 was less extreme, but the average global temperature was still 0.51 degrees Celsius warmer than the average between 1981 and 2010 and the second-warmest April on record for the planet.
In Europe, the biggest temperature anomalies are in the winter with values varying from month to month and April was slightly cooler than the 30-year average. Looking at 12-month periods gives a better idea of long-term trends. For the entire globe, the 12-month period from May 2016 to April 2017 was 0.57 degrees Celsius above average, not that far behind the warmest-ever 12-month period from October 2015 to September 2016, with a temperature 0.64 degrees Celsius above average.
2016 is by far the warmest calendar year on record: its global temperature of 0.62 degrees Celsius above the average for 1981-2010 compares with values of 0.44 and 0.35 degrees Celsius respectively for 2015 and 2005, the two next warmest calendar years.
Various global temperature data sets differ slightly because of they way they represent temperatures in the polar regions, but there is no disagreement about general trends, including:
- the exceptional warmth of 2016, and to a lesser extent 2015;
- the overall rate of warming since the late 1970s;
- the sustained period of above-average temperatures from 2001 onwards.
In April, the southwest of Europe was above average for the month, but the rest of the continent was cooler than the 1981-2010 average.
The Arctic heatwave continued, especially over much of the Arctic Ocean, over northeastern Russia and western Alaska, offshore of West Antarctica and the Ross Ice Shelf, where sea-ice cover remained extremely low, and over the Ross Ice Shelf itself. Temperatures were also well above normal over the eastern USA, Morocco, South Sudan and Uganda, and much of the Middle East and southern and eastern Asia.
Temperatures were most below average over the Weddell Sea and some other parts of the Antarctic, and over the northeast of Greenland and the Greenland Sea to the east. Much of Canada was also colder than average. Weaker cold temperature anomalies occurred over parts of all continents.
Temperatures were predominantly above average over the oceans, but April was relatively cool over some parts of the Pacific, Atlantic and Indian Oceans.