Study find that the CO2 level currently in the atmosphere is the same as it was 14 million years ago

In a recent study published in the Science journal, researchers have found that the current atmospheric carbon dioxide (CO2) level is comparable to levels seen 14 million years ago. The study, covering a time span of 66 million years, used geochemical and biological signatures from the past to reconstruct the historic CO2 record with detailed precision.

The lead author of the study, Baerbel Hoenisch from the Columbia Climate School’s Lamont-Doherty Earth Observatory, emphasized the unprecedented nature of current CO2 levels in Earth’s history. The analysis revealed that the last time there was a presence of 420 parts per million (ppm) of carbon dioxide in the air was between 14-16 million years ago. During this period, ice was absent in Greenland, and the ancestors of humans were transitioning from forests to grasslands.

This timeframe surpasses the 3 to 5 million years studied in previous analyses. Before the late 1700s, atmospheric carbon dioxide was around 280 ppm. Human activities have led to an increase in the greenhouse gas by about 50%, contributing to a 1.2-degree Celsius warming of the planet compared to pre-industrialization.

Homo sapiens, the human species, evolved around 3 million years ago. Hoenisch highlighted the significance of the current CO2 levels, as human civilization has evolved with the current sea levels, warm tropics, cool poles, and temperate regions with abundant rainfall.

If global CO2 emissions continue to rise, projections suggest levels could reach between 600-800 ppm by the year 2100. Such levels were last seen during the Eocene, 30-40 million years ago, a period before Antarctica was covered in ice, and the Earth’s flora and fauna looked vastly different.

The study, conducted by a team of 80 researchers across 16 countries over seven years, is considered the updated consensus in the scientific community, synthesizing, re-evaluating, and validating existing published work based on updated science. The highest-rated data were combined into a new timeline, providing a comprehensive view of historic CO2 levels.