“[F]ive of six continents had a top 10 warm January-June period, with South America experiencing its second highest January-June temperature (tied with 2010),” NOAA said.
The planet’s five warmest starts to the year have all occurred since 2010, according to NOAA data:
- 2016 (1.93 degrees above average)
- 2017 (1.64 degrees above average)
- 2015 (1.55 degrees above average)
- 2010 (1.39 degrees above average)
- 2014 (1.30 degrees above average)
Although 2017’s temperature, so far, has stepped down from 2016, that was expected because of the lack of an El Niño event. During an El Niño, ocean temperatures in the central and eastern tropical Pacific Ocean heat up, and some of that heat is dispersed into the atmosphere, elevating temperatures.
The El Niño event that ended in 2016 was among the strongest on record, and the year closed as the warmest.
NASA climate scientist Gavin Schmidt developed a visualization that shows the unusual warmth of 2016 and 2017 relative to the group of preceding years dating back to 1880:
Here is an animated version:
The high temperatures in recent years have occurred as greenhouse gas levels in the atmosphere, because of human activity, have reached record highs. In a news release last week, NOAA announced its index for tracking greenhouse gases was up 40 percent since 1990.
“We know that rising greenhouse gas emissions are continuing to trap more and more of the sun’s heat in the Earth system,” said James Butler, director of NOAA’s Global Monitoring Division.