The Northern Hemisphere may be transitioning into fall, but there has been no let up from extreme heat. New data shows last month was the hottest September – the fourth consecutive month of such unprecedented heat – putting 2023 firmly on track to be the hottest year in recorded history. September beat the previous monthly record set in 2020 by a staggering 0.5 degrees Celsius, according to data released Wednesday by the European Union's Copernicus Climate Change Service. There has never been a month so abnormally hot since Copernicus' records began in 1940. "The unprecedented temperatures for the time of year observed in September – following a record summer – have broken records by an extraordinary amount," said Samantha Burgess, deputy director of Copernicus, in a statement. September felt more like an abnormally hot July with an average global air temperature of 16.38 degrees Celsius (61.45 Fahrenheit), making the month 0.93 degrees Celsius hotter than the 1991 to 2020 average, and 1.75 degrees Celsius hotter than the September average for the pre-industrial era, before the world started burning large amounts of fossil fuels. That's well above the 1.5 degrees Celsius threshold to which countries aim to limit global warming under the Paris Climate Agreement. While that agreement focuses on longterm average temperatures, September's abnormal heat – which followed the hottest summer ever recorded – has given a preview of what the world can expect as soaring temperatures supercharge extreme weather. September alone brought devastating flooding that killed thousands in Libya and dozens across Greece, Bulgaria and Turkey. Canada grappled with its unprecedented wildfire season, parts of South America were scorched by record-breaking heat and record rainfall deluged New York. Ocean temperatures were also off the charts in September. Average sea surface temperatures reached 20.92 degrees Celsius (69.66 Fahrenheit), the highest on record for September and the second-highest on record for any month, after August of this year. Antarctic sea ice also reached record lows for this time of year. "This month was, in my professional opinion as a climate scientist – absolutely gobsmackingly bananas," Zeke Hausfather, a climate scientist, posted on X (formerly Twitter) on Tuesday. Even in October, there is little sign of heat dying down. European countries, including Spain, Poland, Austria and France, have already broken their all-time October temperature records, according to Maximiliano Herrera, a climatologist and weather historian who tracks extreme temperatures. What Europe experienced in the first three days of October was "one of the most extreme (climate) events in European history," Herrera posted on X on Tuesday. It now appears all but certain that this year will be the hottest year on record. The US National Oceanic and Atmospheric Administration puts the chances of reaching this milestone at more than 93%. The extreme September "has pushed 2023 into the dubious honor of first place – on track to be the warmest year and around 1.4 degrees Celsius above pre-industrial average temperatures," Burgess said. The high temperatures have been partially fueled by El Niño, the natural climate pattern that originates in the tropical Pacific Ocean and has a warming effect. But underlying that pattern is the longterm trend of human-caused climate change. "Temperature records continue to be broken because we have not stopped burning fossil fuels. It is that simple," said Friederike Otto, senior lecturer in climate science at the Grantham Institute for Climate Change and the Environment in the UK. The significant margin by which heat records are being broken matters, she told CNN. "People and ecosystems are dying." Countries will gather in Dubai for the United Nations COP28 climate summit in December where they will assess progress towards climate goals. The world is currently a long way off track, according to a recent report. "The significant margin by which the September record was broken should be a wake-up call for policymakers and negotiators ahead of COP28," Otto said, "we absolutely must agree to phase out fossil fuels." — CNN
