evidence: Based on the annual report from NOAA’s Global Monitoring Lab, global average atmospheric carbon dioxide was 419.3 parts per million ("ppm" for short) in 2023, setting a new record high. The increase between 2022 and 2023 was 2.8 ppm—the 12th year in a row where the amount of carbon dioxide in the atmosphere increased by more than 2 ppm. At Mauna Loa Observatory in Hawaii, where the modern carbon dioxide record began in 1958, the annual average carbon dioxide in 2023 was 421.08. [...] By the time continuous observations began at Mauna Loa Volcanic Observatory in 1958, global atmospheric carbon dioxide was already 315 ppm. Carbon dioxide levels today are higher than at any point in human history. In fact, the last time atmospheric carbon dioxide amounts were this high was roughly 3 million years ago, during the Mid-Pliocene Warm Period, when global surface temperature was 4.5–7.2 degrees Fahrenheit (2.5–4 degrees Celsius) warmer than during the pre-industrial era. Sea level was at least 16 feet higher than it was in 1900 and possibly as much as 82 feet higher.