Barring the unforeseeable, the latest monthly climate report from the National Oceanic and Atmospheric Administration is a clincher. There can no longer be any meaningful doubt that 2015 will be the Earth’s warmest year on record, at an entirely different level from the previous warmest years.
This year’s average temperature through October is running 1.55 degrees (0.86 Celsius) above the 20th century average, 0.22 degrees above 2014, the previous warmest year. NOAA points out 2015’s lead over 2014 is “larger than the uncertainty associated with the dataset” leaving no question 2015 is in unprecedented territory in the current era.
NASA climatologist Gavin Schmidt tweeted Tuesday that there is a 99.9 percent the year will close as the warmest.
Eight of 10 months in 2015 have ranked as the warmest on record, including the last six, according to NOAA. The only months which weren’t the warmest, January and April, ranked second and third warmest in records that date back to 1880.
Consistent with analyses from the Japan Meteorological Agency and NASA, NOAA said it was the warmest October on record by an unprecedented margin (0.31 degrees).
Six of seven of the largest monthly global temperature departures from normal , out of a possible 1630 months, have occurred this calendar year, with October at the top of the list.
In October, “large regions of Earth’s land surfaces were much warmer than average,” NOAA said. “Record warmth was observed across the entire southern half of Australia, part of southern and southeastern Asia, much of central and southern Africa, most of Central America and northern South America, and parts of western North America.”
October ocean temperatures also achieved their highest levels recorded during the month. Fueled by a record-challenging El Niño event, record warm and much warmer-than-average temperatures spanned much of the central and eastern tropical Pacific.
El Niño events, which not only warm the tropical Pacific but also release vast quantities of heat into the atmosphere, have a long history of pushing the warming climate to new records. The time series chart below, released by NOAA, shows the unmistakable El Niño signal in the course of the global average temperature over the last several decades:
In its October State of the Climate report released today, NOAA made the following observations about this chart:
First, nearly every month since 1980 has been above the 20th century average, and has generally warmed through the period. Second, El Niño-like conditions (those months in red) tend to be warmer than neighboring periods, and La Niña-like conditions (blue) tend to be cooler. Third, protracted El Niño-like episodes tend to warm through the event, while La Niña-like episodes tend to cool through the event. Fourth, and finally, there are exceptions to all of the above points.
With El Niño forecast to remain strong into the winter, global average temperatures are likely to continue making history.