2021 saw record-high greenhouse gas levels, new report says

The annual State of the Climate report published Wednesday shows that in 2021, greenhouse gas levels, global sea levels, and ocean heat reached record highs.

The international report was led by scientists from the National Oceanic and Atmospheric Administration's National Centers for Environmental Information. "The data presented in this report are clear — we continue to see more compelling scientific evidence that climate change has global impacts and shows no sign of slowing," NOAA Administrator Rick Spinrad said in a statement. "With many communities hit with 1,000-year floods, exceptional drought, and historic heat this year, 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."

The Environmental Protection Agency says greenhouse gas emissions from human activities "are the most significant driver of observed climate change since the mid-20th century," and the report found that in 2021, the worldwide average atmospheric carbon dioxide concentration was 414.7 parts per million (ppm). This is 2.3 ppm greater than the 2020 amount, the State of the Climate report says, and the highest amount measured since instrumental records began in 1958.

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The study also found the ocean heat content is "indicative of steadily increasing heat in Earth's system" and for the 10th year in a row, the global average sea level increased by roughly 4.9 mm. This is 97 mm higher than the average recorded in 1993, the first year satellite measurements were taken, ABC News reports.

More than 530 scientists from over 60 countries contributed to the report, which "provides the latest synthesis of scientific understanding of the climate system and the impact people are having on it," Paul Higgins, associate executive director of the American Meteorological Society, said in a statement. "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."