In addition, 2020 is likely to be the hottest year when a La Niña event was present in the tropical Pacific Ocean. This climate phenomenon is characterized by cooler-than-average ocean temperatures near the equator in the central and eastern tropical Pacific, and it tends to lower global temperatures slightly. (El Niño events, on the other hand, add even more heat to the planet, causing temperature spikes on top of global warming.)
These trends are all consistent with rapid global warming driven primarily by human emissions of greenhouse gases from burning fossil fuels.
According to the National Oceanic and Atmospheric Administration, the average global temperature in September was 1.75 degrees (0.97 Celsius) above the 20th-century average, surpassing previous records for the month that were set in 2015 and 2016 by about 0.04 degrees (0.02 Celsius).
The 10 warmest Septembers have occurred since 2005, and the seven warmest Septembers have occurred in the past seven years, NOAA stated in a news release.
In the United States, September was a month of devastating climate events, as massive wildfires broke out amid record heat in California, Oregon and Washington. Climate change is already heightening wildfire severity and size in the West, with these trends expected to continue.
Scientists at NOAA rank this year as the second-hottest January-to-September period in the 141-year temperature record, at 1.84 degrees (1.02 Celsius) above the 20th-century average.
NOAA found that three large areas of the globe have had their warmest year so far: Europe, Asia and the Gulf of Mexico. No land or ocean areas have been record cold for the year to date.
Using much of the same data but different methodology, NASA’s Goddard Institute for Space Studies also found that September set a milestone, with a global average surface temperature of 1.8 degrees (1 Celsius) above the 1951-1980 average. This was significantly higher than the second-warmest September in its database, which occurred in 2019, when the month had an average temperature that was 1.67 degrees (0.93 Celsius) above average.
September 2020 was also the first September in NASA’s records to have a temperature anomaly of 1 degree Celsius or greater.
NASA’s data incorporates more of the Arctic than NOAA’s, and the far north is warming at a rate about three times as fast as the rest of the world, with consistently large temperature departures from average seen throughout the year.
This is particularly the case in the Siberian Arctic, where an extended wildfire season has raised fears that a climate feedback loop has kicked into gear and could result in even faster global warming.
During September, Arctic sea ice declined to its second-lowest extent on record. The 14 lowest extents in the satellite era have all occurred in the past 14 years, according to the National Snow and Ice Data Center.
Using another source of data, advanced computer modeling known as temperature reanalysis, the Copernicus Climate Change Service, which is part of the European Commission, also found that September set a record and that the year is headed for one of the hottest on record.
Tracking monthly temperatures is ideal for getting a snapshot of the global climate. However, longer-term data is far more indicative of where the planet, and all the species that call it home, are headed.
The news on that front, too, is unsettling, given that 12-month global average temperatures are near or at record highs and the world has now seen 44 straight consecutive Septembers and 429 straight months “with temperatures, at least nominally, above the 20th-century average,” NOAA found.
A NOAA analysis found that there is a greater than 99.9 percent chance that 2020 will be among the top five warmest years and a 64.7 percent change that it will be the warmest year since instrument records began in 1880.