A fatal virus and a massive economic downturn did not stop planet-warming gases in the atmosphere last year from rising to their highest levels in human history, researchers say. Barely a year after the coronavirus grounded planes, shuttered factories and brought road traffic to a standstill, the associated drop in carbon emissions is all but undetectable to scientists studying our air.
In fact, according to the newly released “State of the Climate in 2020” report from the National Oceanic and Atmospheric Administration, Earth is arguably in worse shape than it’s been.
While humanity grappled with the deadliest pandemic in a century, many metrics of the planet’s health showed catastrophic decline in 2020. Average global temperatures rivaled the hottest. Mysterious sources of methane sent atmospheric concentrations of the gas spiking to unprecedented highs; sea levels were the highest on record; fires ravaged the American West; and locusts swarmed across East Africa.
These findings may sound familiar, coming on the heels of a similarly dire assessment from the United Nations Intergovernmental Panel on Climate Change. And they echo NOAA’s report from last year, which also detailed record-high greenhouse gas levels and unprecedented warmth.
“It’s a record that keeps playing over and over again,” said Jessica Blunden, a NOAA climate scientist who has co-led “State of the Climate” reports for 11 years. “Things are getting more and more intense every year because emissions are happening every year.”
Sometimes Blunden feels like a doctor whose patient won’t listen to health advice, watching a mild illness morph into a chronic disease. By this point, the patient practically has multiple organ failure; “and still they keep eating those Cheeto puffs,” she said.
Without consistent, concerted efforts to reduce emissions from burning fossil fuels and other human activities, scientists warn, Earth’s condition will continue to deteriorate.
NOAA’s assessment, published this week in the Bulletin of the American Meteorological Society, draws on the work of 530 scientists from 66 countries.
In the atmosphere, the researchers found no evidence that last year’s 6% to 7% dip in global annual emissions had any lasting effect. The roughly 2 gigatons of carbon dioxide not emitted during the most severe pandemic-related shutdowns have been dwarfed by the more than 1,500 gigatons humans have unleashed since the Industrial Revolution began.
As Glen Peters, a scientist at the Center for International Climate Research, put it on Twitter: “The atmosphere is like a (leaky) bathtub, unless you turn the tap off, the bath will keep filling up with CO2.”
The average concentration of carbon dioxide in the atmosphere in 2020 was 412.5 parts per million (ppm), about 2.5 ppm above the 2019 average. That is higher than at any point in the 62 years scientists have been taking measurements. Not even air bubbles trapped in ice cores going back 800,000 years contain so much of the gas, suggesting current levels have no precedent in our species’ history.
Carbon dioxide typically lingers in the atmosphere for a few hundred to 1,000 years. Humans will have to stop emitting for much longer than a few months to make a meaningful dent in concentrations of the pollutant.
Even as carbon dioxide emissions briefly slowed, 2020 saw the largest annual increase in emissions of methane. The gas only stays in the atmosphere for about a decade but can deliver more than 80 times as much warming as carbon dioxide in that time frame.
Scientists don’t know why the concentration of methane spiked so dramatically — rising 14.8 parts per billion to its highest level in millennia. The drilling and distribution of natural gas helps drive up methane emissions. But it is also produced by munching microbes, which are found in both natural environments such as wetlands, and human-built ones such as landfills and farms.
“It’s really an ongoing investigation,” said Xin Lan, an atmospheric chemist at NOAA’s global monitoring laboratory in Boulder, Colo.
But Lan has uncovered some clues. The kind of methane that comes from fossil fuel sources disproportionately includes carbon atoms with an extra neutron in their nuclei — a variety, or “isotope,” known as carbon-13. Microbial sources of methane tend to be rich in carbon-12, which lacks the extra neutron and is slightly lighter.
Lately, the proportion of methane carrying the lighter carbon isotope has been rising, suggesting that the recent surge in the greenhouse gas has microbial origins. It might be coming from bacteria in the guts of livestock, or decomposing sludge in landfills.
But the more worrying possibility is that natural methane sources — such as salt marshes, peatlands and mangrove forests — are emitting more as the planet warms. Higher temperatures can boost microbe metabolisms and thaw out permafrost, while rising sea levels may turn some coastal areas into methane-emitting bogs.
“That could be an indication of a climate feedback,” Lan said. “So that would give us an extra challenge in [predicting] the future climate.”
Events from 2020 show that the planet has already changed dramatically in response to human emissions. Depending on the data sets consulted (the NOAA scientists looked at five), last year was either the hottest year in history, tied for first, or among the top three.
The high temperatures were especially noteworthy because they occurred during a La Niña year, when natural variations in the movement of wind and water tend to cool the planet down. No previous year with a La Niña climate pattern has been so hot.
Global average sea levels in 2020 rose for the ninth year in a row, NOAA said — a consequence of melting glaciers and ice sheets and expanding warmer waters. Sea levels are now about 3.6 inches above the average in 1993, when scientists began taking satellite measurements.
The litany of broken records was endless.
The far northern town of Verkhoyansk, Russia, notched a high of 100 degrees Fahrenheit — the hottest temperature ever recorded within the Arctic Circle. On the other side of the planet, Esperanza Station broke Antarctica’s temperature record by 2 degrees Fahrenheit, hitting a balmy 64.9 degrees. Death Valley, Calif. may have seen Earth’s highest temperature in almost a century. Europe, Mexico, Japan and the Indian Ocean archipelago of the Seychelles all saw their hottest years.
And the escalation of extreme weather was devastating.
Super Typhoon Goni was the most powerful storm to make landfall, NOAA said, slamming the Philippines with 195 mph winds. There were so many tropical cyclones in the North Atlantic that meteorologists ran out of letters of the alphabet for naming them; by the time two Category 4 storms hit Nicaragua in a two-week span in November, officials had to use the Greek letters Eta and Iota.
Burning forests and grasslands spewed 1,714 million tons of carbon into the atmosphere. Powerful floods caused devastation to the countries around Lake Victoria in eastern Africa, while Chile endured its 11th year of drought. About 84% of the ocean surface experienced at least one marine heat wave.
“It’s the extremes that really stand out to me,” Blunden said.
But 2021 already rivals last year’s extremes. This July was the hottest month documented, according to NOAA. The Pacific Northwest was scorched by a heat wave that scientists say was “virtually impossible” without human influence. Floods have deluged China, Germany, the United States and Bangladesh. Drought in Madagascar has pushed the nation to the brink of what the United Nations calls the world’s first climate change famine.
“These things are getting more and more intense every year,” Blunden said. “If we don’t slow down greenhouse gas emissions it’s just going to continue … And one way or the other, it’s going to affect all of us.”