warmest year on record. Today, NASA and NOAA are announcing that 2020 was one for the record books, with 2016 tied for the hottest year since we’ve been tracking temperatures. NASA as the hottest rates by 2020, although by a margin that is not large enough to reach statistical significance; The NOAA reverses the order, that too without a significant difference between the two years. Whatever its exact rank, 2020 was a continuation of a worrying trend – the last seven years are on the list of the seven warmest years on record, regardless of which source you turn to for your global temperature.
Another cause for concern is that 2020 saw El Nino-Southern Oscillation (ENSO) in a state that, in the absence of human-driven climate change, produced relatively calm conditions. NASA’s Gavin Schmidt said that, in the absence of ENSO’s influence, 2020 would have been the warmest year for a record. As shown in the chart below, strong El Niño years are associated with warmer records, while cycle contrast conditions, called La Niña, are typically associated with cooler conditions. 2016 was notable for being the strongest El Niño since the 1990s, a phenomenon that pushed temperatures far above the baseline where they spent the most at the beginning of the century.
Since then, ENSO has been largely stuck in neutral between the tendency of weak El Niños and La Niña. Temperatures dropped slightly, but did not return to conditions that were typical of the first decade. Despite a drop in temperature in 2020, the strong El Niño temperatures of 2016 declined. “The previous record warmer year, 2016, received a significant boost from a strong El Niño,” Schmidt said in a statement. “The lack of similar support from El Niño this year is evidence that background climate continues to heat up due to greenhouse gases.”
Despite this, the record temperature was no surprise. A look at the monthly readings is similar to the 2016 temperature throughout the year. In NASA’s analysis April, May, September and October were all record months, making the year’s record-setting anything but surprising.
For those tracking long-term trends, NASA has registered traces that last longer than 28 months in a month, where the average global temperature was lower than the period between 1950 and 1980. NOAA estimates that it has been one year, it has been 44 years. With global temperatures below the 20th century average, meaning there are people who are grandparents who have never experienced an unusually quiet year.
Overall, all of the last few years have been in the neighborhood of 1.2 aboveC above the average temperature of the previous century. It is so close to 1.5ºC of change that many countries have promised to try to stay below. At current rates of change, we can begin to see temperatures above that milestone in a decade or so.
Both NASA and NOAA note that the year saw a variety of events that you might expect in a warming climate. Australia, California and Siberia all saw severe fire seasons, driven by a combination of heat and changed rainfall patterns. And the tropical cyclone season was unusually active, especially in the North Atlantic. While it is difficult to attribute any weather event to climate change, the trends in the overall number of these events are becoming difficult to interpret in any other way through climate change, as NASA explains in the video below .
Overall, the continued warming is notable but fully expected, and it certainly does not challenge our understanding of the effect of greenhouse gases. But this is probably an important verification of science for the public. And that, combined with the “growing frustration of those who oppose doing anything about climate change”, could help smooth the path for the upcoming Biden administration’s plans to address climate change.
NASA and NOAA will host a press conference today; If there is significant new information then we will update this story.