But it wasn’t as unusually warm as the previous seven months.
For the first time since September, May’s temperature difference from normal was less than 1 degree Celsius, NASA data indicate.
Also, an analysis of May’s global temperature from the Japan Meteorological Agency (JMA), showed the month to be the second warmest on record, a tick cooler than 2015.
The slowdown in warming is no surprise since El Niño, the cycle of warm ocean waters in the tropical Pacific Ocean, has ended.
During El Niño events, excess heat from the tropical Pacific flows into the atmosphere increasing the global temperature. When the El Niño cycle ends, that heat source is removed and the temperature starts to level off.
The National Weather Service favors the onset of a La Niña event by late this summer or this fall, during which ocean temperatures in the tropical Pacific are cooler than normal. Thus, it is virtually assured that the global temperature will not sustain levels reached late in 2015 and early 2016, when El Niño ramped up and challenged records.
Even so, since 2016 started off so warm, it is still almost certain to become the warmest year on record.
During the first five months of this year, record warmth and near-record warmth has been observed all over the world.
High latitude locations have been particularly warm, especially Alaska and many other parts of the Arctic.
For the first time, the 12-month running global temperature exceeded one degree C above the baseline in May due to the sustained warmth, notes German climate scientist Stefan Rahmstorf.
The upward spike in temperatures, however, is now poised to level off some.
It is important to note that the expected cooling of the Earth’s temperature compared to recent highs does not mean global warming has stopped or is even slowing.
El Niño and La Niña are constantly pushing and pulling against the long-term temperature trend, which has inexorably moved upwards through many cycles of these phenomena in the past several decades.