Analyses with other temperature data — from the National Oceanic and Atmospheric Administration and NASA, among others — have also shown more than a 50 percent chance that 2023 will be the warmest on record. At the end of June, the nonprofit Berkeley Earth forecast an 81 percent chance of a record 2023.
“I think it is very safe to say at this point that 2023 is the odds-on favorite to be the warmest year on record,” said Hausfather, who had thought 2023 would land as the fifth hottest at the beginning of this year. “What’s changed is the last two months have been incredibly hot, setting records by a very large margin compared to what we’ve seen in the past.”
July was confirmed as the warmest on record of any month, the Copernicus Climate Change Service reported on Tuesday. It was estimated at around 2.7 degrees Fahrenheit (1.5 degrees Celsius) warmer than the preindustrial average and shattered the previous July 2019 record by a whopping 0.59 degrees Fahrenheit (0.33 degrees Celsius).
“In each case the source of the data and the processing is different, but all will be reasonable reflections of what is actually happening. It’s hot,” Gavin Schmidt, Director of the NASA Goddard Institute for Space Studies, tweeted.
The rankings shouldn’t be surprising for anyone who has been living on Earth over the past two months. Phoenix hit daily highs of 110 degrees Fahrenheit for 31 consecutive days. The heat index in the Middle East reached 152 degrees Fahrenheit (66.7 degrees Celsius), near the upper limits for what the human body can tolerate. China reached an all-time high of 126 degrees Fahrenheit. The Southern United States has experienced a historically intense and long heat wave, extending from California to Florida. Warm temperatures have also pushed Antarctic sea ice to all-time lows.
Many of the annual temperature forecasts, Hausfather explained, take into account temperatures so far this year, the predicted El Niño state for the rest of the year and last year’s temperatures to understand the baseline that 2023 will be building on.
The beginning of the year started out cold, and models showed uncertainty in the developing El Niño event. As the year progressed, the forecasts became refined with more data, including warmer monthly temperatures and updated El Niño models. Some forecasts weigh these elements differently, which produces different forecasts, but all are increasingly pointing to an unprecedented 2023.
Hausfather said summer temperatures have rapidly increased as a burgeoning El Niño pattern strengthens. An El Niño pattern is marked by an increase in ocean temperatures in the eastern and central Pacific Ocean, which heat the atmosphere. The year 2016, tied for the warmest year on record, experienced a strong El Niño event early in the year.
Models indicate that this year’s El Niño is expected to be one of the strongest events in recent decades, but Hausfather said it probably won’t be as strong as the one in 2016. But at the same time, he said this year’s event is unusual because it quickly followed three years of La Niña conditions, its counterpart that tends to bring relatively cooler temperatures.
“The La Niña was suppressing the warming we’d otherwise experience in greenhouse gases globally, and now this is enhancing it,” said Hausfather, the climate lead at the payments company Stripe. “Flipping from one to the other, it leads to these fairly large jumps in temperature.”
Human-caused climate is the other major player, sending exceptional amounts of carbon dioxide and other heat-trapping gases into our atmosphere. If warming continues at the current rate, average surface temperatures could exceed and remain above 1.5 degrees Celsius in the mid-2030s, which scientists say would result in a range of new climate disasters. The World Meteorological Organization predicted that the annual temperature could even temporarily reach above 1.5 degrees Celsius for at least one year in the next four years.
Scientists may not know how many degrees warmer this year will end, but Hausfather said he expects “much of the rest of the year to be in record territory.” Even if temperatures were to go down for the rest of the year, he said we’re still more likely than not going to see a record.
And that’s just 2023. Some scientists, including Hausfather, think 2023 may just be a preamble to an even hotter year, when El Niño conditions are in full force.
“There’s a lot of reason to suspect that the El Niño conditions that are currently growing are more likely to impact 2024 temperatures overall than this year,” he said.