Warming overpowers La Nin˜a
Last year tied with 2016 for Earth’s warmest year on record, capping off the warmest decade ever observed, according to new data from the Copernicus Climate Change Service, a programme of the European Commission.
Each of the past six years have been hotter than all of the years before 2015 in records that date back to the late 19th century, Copernicus reported.
Globally, 2020 was 0.6 degrees Celsius warmer than the 1981-2010 average, and about 1.25C above the 1850-1900 pre-industrial period.
The climate agency released its year-end numbers yesterday ahead of Nasa, the United States National Oceanic and Atmospheric Administration and Berkeley Earth, which will report their results on January 14.
In the Copernicus data, 2020 would have held the top ranking by itself if it wasn’t for a slightly cool December relative to the rest of the year.
To climate scientists, this is alarming, since 2016’s record was aided by a largely natural climate cyclone known as El Nin˜o, which features above-average sea surface temperatures across the tropical Pacific Ocean near the equator.
An unusually intense El Nin˜o occurred in 2016, changing global weather patterns. But instead of El Nin˜o being present this year, the phenomenon’s colder sibling, La Nin˜a, took hold in the tropical Pacific.
What’s happening now, scientists say, is that even La Nin˜a years are setting global temperature records, due to the overpowering influence of humancaused warming from decades of greenhouse gas emissions.
‘‘These record years are just going to continue,’’ said Sue Natali, a climate researcher who directs the Arctic programme at the Woodwell Climate Research Centre in Massachusetts.
‘‘ I’m not sure how extreme things have to get for the message to get across that we’re heading into a climate emergency unless we take some ambitious and immediate action to control global climate change.’’
With more greenhouse gases in the air each year – atmospheric concentrations hit a record high of 413 parts per million in 2020, according to Copernicus – each La Nin˜a year is likely to be warmer than the last, and each El Nin˜o is likely to set a record as well.
‘‘2020 stands out for its exceptional warmth in the Arctic and a record number of tropical storms in the North Atlantic,’’ said Copernicus director Carlo Buontempo. ‘‘ It is yet another
reminder of the urgency of ambitious emissions reductions to prevent adverse climate impacts in the future.’’
Some of 2020’s most extreme climate conditions were in northern Siberia and parts of the Arctic, with annual average temperatures 3-6C above normal.
The warmer than usual conditions there had major consequences. Wildfires in the Siberian Arctic began early, in May, and continued until October. The fires set a record for the amount of carbon dioxide released from
wildfires north of the Arctic Circle, according to Copernicus.
During one extreme heatwave, the mercury climbed to 38C on June 20 in the remote Siberian town of Verkhoyansk – the highest temperature in the Arctic since record-keeping began in 1885.
They also may have destabilised vast areas of previously frozen ground known as permafrost, emitting carbon dioxide, methane and other global warming gases.
‘‘ These record- setting years and record-setting months can have a disproportionate impact due to the occurrence of extreme events and disturbances, such as abrupt permafrost thaw and wildfires, that have long-lasting impacts on the landscape and on carbon emissions,’’ said Natali, a permafrost expert.
The year was marked by a parade of extreme weather disasters, some of them long predicted by climate scientists but occurring earlier and with greater ferocity than expected.
It started with deadly wildfires in Australia that scorched some of the country’s most biologically rich ecosystems, killing or harming nearly 3 billion animals. It then featured the busiest Atlantic hurricane season on record, with the most named storms to make landfall in a single season in US history.
California has its worst fire season on record – five of the top six largest wildfires in the state’s history occurred last year. At one point, fires burned from Washington state to southern California and east to Colorado. Studies have linked the increase in large and intense Western blazes to climate change.
According to Munich Re, losses from natural disasters in 2020 totalled US$210 billion (NZ$290b), which the reinsurance giant tied in part to global warming.