Long Term Warming Trends Tell Us What We Need to Know

It’s official, despite cooling from a La Niña event, 2020 has tied 2016 as the warmest year on record, ending the warmest decade on record. These findings were released by Copernicus Climate Change Service (C3S) on January 8, 2021.

In 2020 we saw the hottest temperature ever reliably recorded. Death Valley California saw temperature readings of 54.4 C (129.92 F) on August 17, 2020. Last year’s heat contributed to unprecedented extreme weather including a record setting Atlantic storm season and pervasive wildfires. As explained by Penn State University professor Michael Mann, this year’s heat is “way out of balance”.

This warming is being driven by anthropogenic greenhouse gas (GHG), primarily from the burning of fossil fuels. Despite an estimated seven percent reduction in fossil CO2 emissions due to the COVID-19 pandemic, GHGs continued to increase in 2020. The increase of 2.3 parts per million (ppm) of atmospheric carbon is slightly less than the year before.

Vincent-Henri Peuch, Director of the Copernicus Atmosphere Monitoring Service (CAMS), says the small reduction in emissions is not a cause for complacency. At 413ppm of atmospheric CO2, this is their highest level in at least 800,000 years. “Until the net global emissions reduce to zero, CO2 will continue to accumulate in the atmosphere and drive further climate change. We must continue efforts to decrease CO2 net emissions to reduce the risk of climate-related change” Peuch said.

Europe saw its warmest year on record in 2020, but the area with the largest annual temperature deviation was the Arctic. Scientists pay particular attention to Arctic heatwaves because they have planetary implications. In October, the average temperature for the whole circumpolar Arctic was 6.7 C. In the Russian Arctic archipelago of Severnaya Zemlya, the average temperature was 10 C above the average. Arctic heat also links wildfires to climate change; according to C3S, Arctic wildfires released a record 244 megatonnes of carbon dioxide in 2020. Arctic sea ice was significantly below average and the months of July and October had the lowest sea ice extent on record.

Scientists like C3S Director Carlo Buontempo have expressed concern. “2020 stands out for its exceptional warmth in the Arctic and a record number of tropical storms in the North Atlantic. It is no surprise that the last decade was the warmest on record, and is yet another reminder of the urgency of ambitious emissions reductions to prevent adverse climate impacts in the future,” Buontempo,said.

Last year, all time heat records were set in the months of January, September and November. While individual months are of interest, climate change is about long term trends. The last six years have been the six warmest on record. Nine of the last ten years are the warmest on record. Month after month, year after year decade after decade temperature records keep being broken. The five warmest decades on record have all occurred in the last 50 years and each successive decade was warmer than any preceding decade. We have seen 432 consecutive months with temperatures above the twentieth-century average and 44 consecutive years with above average global land and ocean temperatures. We have not seen a month with below average temperatures in 37 years.

Matthias Petschke, Director for Space, European Commission’s Directorate-General for Defence industry and Space summarized the situation as follows:

“The extraordinary climate events of 2020 and the data from the Copernicus Climate Change Service show us that we have no time to lose. We must come together as a global community, to ensure a just transition to a net zero future. It will be difficult, but the cost of inaction is too great”.

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