The last seven years have been the seven warmest on record for the planet, new data shows, as Earth's temperature continues its precarious climb due to heat-trapping fossil fuel emissions.
A new analysis by the European Union's Copernicus Climate Change Service, which tracks global temperature and other climate indicators, found 2021 was the fifth-warmest year on record.
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Though the long-term trend is up, yearly fluctuations in global temperature are expected, mainly because of large-scale weather and ocean patterns like El Niño and La Niña, the latter of which was present in 2021 and tends to lead to cooler global temperature.
"The really important thing is to not get hung up on the ranking of one particular year but rather kind of see the bigger picture of ever-warming temperatures, and that ever-warming doesn't mean every year will be warmer than the next," said Freja Vamborg, senior scientist at Copernicus. "But that was what we've seen so far with every decade warmer than the next — and this is quite likely to continue."
Earth's average temperature is around 1.1 degrees Celsius above average pre-industrial levels, Copernicus reports, 73% of the way to the 1.5-degree threshold scientists warn the planet must stay under to avoid the worst impacts.
Kim Cobb, director of the Global Change Program at the Georgia Institute of Technology, said a warming of 1.1 degrees Celsius is a "conservative" estimate.
"It is very fair to say that 1.1 degrees Celsius is conservative, because the last half of the last decade has been warmer than the first half," Cobb, who is not involved with the report, told CNN.
Even at 1.1 degrees, 2021 made abundantly clear the world is already feeling unprecedented effects of the climate crisis many are not prepared for, including significant melting events in the Arctic, deadly floods, unprecedented heat waves and historic droughts. Copernicus also found global greenhouse gas concentrations — the root cause of the climate crisis and its worsening disasters — continued to surge.
In 2015, world leaders agreed to heed scientists' warnings and limit Earth's rapid temperature rise to below 2 degrees Celsius above pre-industrial levels, with a preferred goal of 1.5 degrees.
That threshold may not sound like much, but NASA scientists say it's similar to how a 1 or 2 degree increase in body temperature can lead to a fever. With every fraction of a degree of warming, the illness worsens with increasing likelihood of needing hospitalization.
For the planet, scientists are tracking Earth's temperature increase from the baseline at the start of the Industrial Revolution in the mid-to-late 19th century, when humans ramped up the burning of fossil fuels like coal and oil.
Cobb said for every increment of future warming, the latest climate research outlines cascading consequences that would threaten every aspect and necessity on Earth including biodiversity, freshwater, and food supplies.
"We've just barely crossed the 1 degree threshold for warming, and yet we are reeling from a near-constant series of weather and climate extremes," Cobb told CNN. "With rare exceptions, these extremes can now be definitively linked to human-caused warming. Going forward, we should expect the frequency and severity of such extremes to increase, exacting an enormous toll on societies around the world."
2021 brought heat waves and floods that became mass-casualty events; rain fell at the summit of Greenland for the first time ever on record; and a historic drought plagued much of the Western U.S. and triggered large, destructive wildfires and never-before-seen water shortages.
Almost every corner of the world felt the effects of the rapidly warming planet. Copernicus researchers pointed to several regions that saw the most above average temperatures in 2021, spanning the Western U.S. and Canada to Greenland, as well as large swaths of central and northern Africa and the Middle East.
Summer in Europe last year was the warmest on record, the agency reported, with several extreme weather events wreaking havoc across the continent, including the deadly floods in Germany, Belgium and the Netherlands as well as the intense wildfires in the eastern and central Mediterranean.
In North America, the analysis found periods of incredible temperature deviations from the norm, including the blistering heat wave in the Pacific Northwest and British Columbia. It also noted the widespread impacts of the Dixie Fire — the second-largest wildfire ever recorded in California — which wafted harmful smoke across the continent.
As the symptoms of a fevered planet worsen, the UN's Intergovernmental Panel on Climate Change concluded in August the only way to halt the alarming trend is by making deep cuts to greenhouse gas emissions, while also removing the planet-warming gases humans have already put into the atmosphere.
'Inspiring' reason for hope
In November, the watchdog Climate Action Tracker warned the world is on track for 2.4 degrees of warming, if not more — despite countries' new and updated climate pledges, including those made at the UN climate conference in Glasgow.
Experts warned global greenhouse gas emissions in 2030 will still be roughly twice as high as what's necessary to limit warming to 1.5 degrees. Even worse, under current policies — not proposals, but rather what countries are actually doing right now — the climate tracker projects global temperatures to climb a catastrophic 2.7 degrees Celsius.
At that point, the planet would be in critical condition. The Copernicus report showed carbon emissions continued a precipitous trend in 2021, despite a global pandemic. Emissions from methane, a greenhouse gas roughly 80 times more potent than carbon dioxide in the short-term, continued to rise "very substantially."
Vamborg highlighted the report serves as a reminder the rise in greenhouse gas emissions is what fuels the planet's rapid warming, adding the "global temperature curve will continue going up as we continue emitting greenhouse gases."
Humanity's reward for stopping the planet from crossing 1.5 degrees, Cobb said, should be more than enough to elicit bold and collective action. Choosing to limit fossil fuel emissions to that point could "potentially cool the planet in the second half of this century."
"The idea that we might live to see a reversal of global warming is inspiring, as generations that have witnessed decade after decade of warming," Cobb said. "It's a future worth fighting for, and bringing to life, one energy choice at a time."