Northern Hemisphere just had its warmest summer on record

The Northern Hemisphere just had its hottest summer on record since 1880, according to National Oceanic and Atmospheric Administration data released Monday. NOAA found the average global surface temperature taken by thousands of thermometers, buoys and other sensors on land and sea tied with that of 2016 for the top spot, with a temperature anomaly of 2.03 degrees above the 20th-century average.

In addition, August was the world’s second-hottest such month, according to both NOAA and NASA, with unusually hot conditions seen from pole to pole and across every ocean.

What’s remarkable about 2019’s record warmth is that it comes in the absence of a strong El Niño event in the tropical Pacific Ocean. Such events tend to boost global temperatures by warming the seas and sending more heat into the atmosphere. Instead, a weak El Niño has been present at times during 2019 but nothing like what occurred in 2016, which was the last time a Northern Hemisphere summer was this warm.

As global average temperatures continue to rise in response to increasing levels of human-produced greenhouse gases, it is becoming easier to exceed climate benchmarks even without strong El Niño events. For example, according to NOAA, the five hottest summers in the Northern Hemisphere have each occurred during the past five years.

This summer featured unusual events that are symptomatic of a rapidly warming planet. There was a brutal heat wave across Europe in July that established new national high temperature records and broke Paris’ all-time hottest temperature. In addition, Arctic sea ice plummeted to the second-lowest level on record for the month of August.

Furthermore, the Arctic was ablaze, from the boreal forests of Alaska and Canada to the Siberian tundra and vast spruce forests, highlighting the possibility that the region could go from an absorber, or “sink,” of carbon to a source of additional carbon dioxide emitted into the atmosphere.