June 2023 didn’t seem like a special month back then. It was the warmest June on the instrumental temperature record, but monthly records are not unusual in a period in which all of the 10 warmest years on record have occurred in the last 15 years. And monthly records often occurred in years that would otherwise be unremarkable; at the time, the warmest July on record was in 2019, which isn’t much different from the rest of the last decade.
However, July 2023 set another monthly record, easily breaking the high temperatures of 2019. August then set another monthly record. And that’s been the case every month since then – a string of records have made 2023 the warmest year since tracking began.
On Wednesday, the EU’s Earth monitoring service Copernicus announced that it’s already a full year where every month is the warmest version of that month because there are enough instruments to track global temperatures.
The monthly temperature history shows how extreme temperatures have been over the past year.Courtesy of C3S/ECMWF
As you can see from this chart, most years the temperatures vary – some higher than average, some lower. Exceptionally high months tend to cluster together, but these groups also tend to be shorter than a full year.
In Copernicus data, a similar annual streak of records has already occurred once, in the 2015/2016 season. NASA, which uses slightly different data and methods, does not show a similar streak during this earlier period. NASA hasn’t released its May temperature results yet – they’re expected in the next few days – but it’s very likely that those results will also show a multi-year streak of records.
Beyond records, the EU highlights the fact that the annual period ending in May was 1.63 degrees Celsius higher than average temperatures from the period 1850-1900, which form the basis for pre-industrial temperatures. This is noteworthy because many countries have reportedly committed to maintaining temperatures above 1.5 degrees Celsius above pre-industrial conditions by the end of the century. While it is likely that temperatures will fall below the target again in the next few years, the fresh data suggests we have a very constrained amount of time before temperatures consistently exceed it.
For the first time in history, temperatures were consistently more than 1.5 degrees Celsius above the pre-industrial average.Courtesy of C3S/ECMWF