July was Earth's hottest month ever recorded, "on a par with, and possibly marginally higher" than the previous warmest month, which was July 2016, according to provisional data from the Copernicus Climate Change Service. This European climate agency will have a full report for all of July on Monday, but a spokesperson said enough data (through July 29) has already come in to make this declaration.
The monthly global average temperature anomaly was 1.2C above preindustrial levels, the center reported in its preliminary figures Friday.
On Thursday, United Nations Secretary General António Guterres cited the data at a news conference as an example of why more ambitious action to cut planet-warming greenhouse gases is needed.
Through the Paris Climate Agreement, world leaders have committed to preventing the globe from warming more than 2C, and are trying to keep global warming even more limited, to 1.5C, relative to preindustrial levels.
July's numbers clearly indicate that the planet is already lapping up against the lower threshold. It also means the world is headed for a top 3 warmest year, up from a top-5 warmest ranking earlier in the year. The period from 2015 to 2019 will go down in history as the warmest 5-year period on record since the late 19th century, and very likely well before that.
The temperature spike was driven largely by record warmth in Western Europe, noteworthy warmth stretching across the Arctic that culminated in one of the most significant melt events ever recorded in Greenland at the end of the month.
During the entire month of July, the Greenland ice sheet poured 197 billion tons of water into the North Atlantic in July alone, enough to raise global sea levels by 0.5mm.
Noteworthy extreme weather events during July include a widespread heat wave in Western Europe that set national temperature records in the Unoited Kingdom, Germany, The Netherlands, and Belgium. Paris soared to its highest temperature ever recorded, 42.6C.
A study released Friday from a group of researchers that study climate change's possible role in extreme weather and climate events found that climate change made this heat wave at least 10 times more likely to occur compared to a climate without an increased amount of greenhouse gases, such as carbon dioxide.
The report, from World Weather Attribution, also found that by raising global average surface temperatures, climate change boosted the heat wave's temperatures by up to 3C.
"The July 2019 heat wave was so extreme over continental Western Europe that the observed magnitudes would have been extremely unlikely without climate change," the report, which has not been peer-reviewed by an academic journal, states.
Elsewhere during July, Alaska saw its warmest month on record, and across the Arctic, a record flare-up of simultaneous, large and persistent wildfires erupted from Siberia to northern Alaska. These fires have consumed millions of acres and emitted large amounts of greenhouse gases, constituting a positive feedback loop by worsening future global warming.
Arctic sea ice was at a record low for the month, and it's possible, though not assured, that 2019 will see a record low for sea ice extent in the Arctic. The previous record was set in 2012, and numerous scientific assessments show the Arctic will be seasonally ice-free as early as the 2040s under continued global warming, even if emissions of greenhouse gases are curtailed in the near-term.
Copernicus, a climate services program from the European Union, reports its monthly temperature rankings earlier than other temperature tracking agencies such as NASA, and their rankings may differ slightly as well. This is because they use a different source for their data.
The ranking was generated using what are called reanalysis records, which take data collected for weather forecasting and feed many different observational variables into a weather model for each hour of every month.
Reanalysis data tends to allow for faster reporting of monthly global temperatures, but still must be checked against observational records gathered from networks of thousands of measuring sites worldwide.
Those readings will be reported by NASA, NOAA and other agencies in the coming weeks, but they're not likely to differ significantly from Copernicus.
The monthly temperature record comes without the added warming influence of a strong El Niño event in the tropical Pacific Ocean. Such events add heat to the oceans and atmosphere, and help boost planetary temperatures. The 2016 record, for example, occurred during a year with a strong El Niño. The lack of an El Niño this July shows how much easier it is to set temperature records on a rapidly warming planet.