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"Alarming year for extremes": 2021 saw record-high greenhouse gas, ocean heat and sea levels rise, new report finds

A new report from NOAA and the American Meteorological Society paints a clear picture of the state of the planet: The climate crisis is not a future threat, but one that's already here. 

The annual State of the Climate report found that 2021 was among the hottest years as the world saw record-high greenhouse gas concentrations, ocean heat and sea level rise, indicating that the effects of climate change are just getting worse. 

The report, based on research from more than 530 scientists in more than 60 countries, is the "most comprehensive update" on Earth's climate and environmental update, according to NOAA. 

And their findings were daunting. As climate scientist Zack Labe, who contributed to the report, said, "unsurprising, it was another alarming year for extremes." 

A graphic from the report shows the wide range of areas affected by the climate crisis in 2021: Canada hit a new record high of more than 121 degrees Fahrenheit; Brazil's Rio Negro River hit record-high levels with floods that surpassed the damage of the "once-in-a-century" flood that hit in 2012; New Zealand had its warmest year in its 113-year record; eastern Africa had its worst food security in decades amid ongoing drought; and sea ice struggled to maintain its size. 

Here are some of the report's most notable findings. 

Record-high greenhouse gas concentrations

Carbon dioxide, methane and nitrous oxide are the three most notable greenhouse gases that, once emitted, create a sort of cloak over the atmosphere that traps the sun's radiation, warming the planet. Last year, the concentrations of each of those gases hit a record high.

Carbon dioxide, which accounts for the greatest amount of global warming associated with human activities, notably the burning of fossil fuels, had a concentration of 414.7 parts per million – the highest in at least the last million years based on paleoclimatic records. Methane saw an increase of 18 parts per billion as its concentrations continue their steep increase since 2014. And nitrous oxide saw its third-highest annual increase since 2001, at 1.3 parts per billion. 

Earth continues to set new heat records 

Regional temperatures soared throughout the world last year, with many countries experiencing devastating heat waves, and in some cases, all-time heat records. Canada, for example, hit an unprecedented 121 degrees Fahrenheit, as China hit its warmest year in its 71-year record and Sicily broke Europe's highest temperature ever recorded at just under 120 degrees. 

The dozens of researchers who were part of the report found that the last seven years, from 2015 to 2021, were the seven warmest on record. Earth's global average surface temperature has increased between 0.14 and 0.16 degrees Fahrenheit on average every 10 years since 1880. That's only accelerated since 1981 – with an average of more than twice that amount. 

However, these record highs were not seen everywhere.   

A "double dip" of La Niña, a pattern during which abnormally strong trade winds push warm water toward Asia and churn colder water to the surface closer to the Americas, helped spark Australia's coolest year since 2012. Antarctica also saw its coldest winter on record at the South Pole as a polar vortex emerged. 

These instances don't mean that warming wasn't taking place, but rather, were the result of weather events and patterns.  

The Arctic, for example, which was recently discovered to be warming nearly four times faster than the rest of the planet, had its coldest year since 2013. But even that brief bit of cold was still the region's 13th warmest year on record as the amount of Arctic sea ice able to survive multiple melting seasons hit its second-lowest rate. 

Warming and rising oceans 

The decline of sea ice, which is able to reflect the sun's radiation and prevent it from getting into the depths of the ocean, is taking a toll on the oceans. The seas hold 90% of the planet's warming, and when there is less protection but more of an attack from the increased greenhouse gas concentrations and hotter temperatures, oceans will warm and the melting ice will cause a rise. 

Last year, global ocean heat content, which measures temperatures from the surface to more than 6,000 feet below, reached a record high. Global average sea levels also saw a record-high as they rose just under 4 inches from the 1993 average when satellite measurement records began. 

And the rising seas will only continue to do so. A new study published this week found that Greenland's "zombie ice" – ice still attached to thicker areas but not getting fed by larger glaciers – will alone raise global sea levels by at least 10 inches. 

That's going to happen regardless of what the world does to tackle climate change, meaning that, at a minimum, many coastal areas are facing a devastating, if not deadly, future. The global average means that some areas will see an even higher surge and face extreme tides and storms. Researchers don't know when this will happen, but say it could happen within the next 80 years, making climate resilience strategies more important than ever. 

Information for mitigation and adaptation 

While the report paints a grim picture of the state of the planet, researchers said that, taken seriously, it can help governments better plan to tackle climate change and better adapt their nations for the sure things to come. 

"The 2021 AMS State of the Climate provides the latest synthesis of scientific understanding of the climate system and the impact people are having on it," Paul Higgins, American Meteorological Society associate executive director, said. "If we take it seriously and use it wisely, it can help us thrive on a planet that is increasingly small in comparison to the impact of our activities."

Many of the existing ramifications of climate change – prolonged droughts, hotter temperatures and more intense storms – cannot be reversed. As UCLA Institute of the Environment and Sustainability ecology researcher and professor Dan Blumstein previously told CBS News, the changes that must be made today will ensure that the current state of things does not get drastically worse

"You can't put the genie back in the bottle," he said. "The devil with climate change is, we can stop burning carbon tomorrow, all carbon tomorrow, and we would still have burning effects from the carbon that's in the atmosphere." 

NOAA administrator Rick Spinrad said that the data presented in the report are "clear": "We continue to see more compelling scientific evidence that climate change has global impacts and shows no sign of slowing." 

"With many communities hit with 1,000-year floods, exceptional drought and historic heat this year," he said, "it shows that the climate crisis is not a future threat but something we must address today as we work to build a Climate-Ready Nation — and world — that is resilient to climate-driven extremes."

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