Carbon Dioxide Levels Haven’t Been This High Since Greenland Was Ice-Free, Study Finds
According to a study published in Science on Friday, the levels of atmospheric carbon dioxide today are the highest they’ve been in 66 million years. This has scientists warning that the Earth is in for some major changes unless action is taken to reverse the trend.
The last time carbon dioxide levels were as high as they are today, Greenland was free of ice and the savanna and grassland ecosystems where humans evolved didn’t exist yet, the study concludes.
The lead author of the study, Baerbel Hoenisch of the Columbia Climate School’s Lamont-Doherty Earth Observatory, told France Media Agency, “It really brings it home to us that what we are doing is very, very unusual in Earth’s history.” Hoenisch added, “We’ve already pushed the atmosphere way beyond anything we’ve seen as a species.”
Industrial capitalism has raised global carbon dioxide levels to 419 parts per million today from around 280 parts per million at the beginning of the industrial revolution. Gabe Bowen, the corresponding author of the study and a geologist at the University of Utah, emphasized on social media, “The concentration has risen by ~50% in the past 100 years. Every year is now marked by the highest CO2 levels *ever observed* by humans!”
To understand the impact of such a spike in carbon dioxide, researchers turned to the past. However, the most reliable record of past carbon dioxide concentrations only goes back to around 800,000 years ago, posing challenges for researchers.
Scientists have relied on proxies, such as mineral isotopes or the shape of fossilized leaves, to estimate carbon dioxide levels in the distant past. The study represents the most comprehensive effort to date, involving a team of around 90 researchers from 16 countries who spent seven years synthesizing and reviewing previous work.
The scientists concluded that the last time carbon dioxide levels were around 419 parts per million was 14 million years ago, far earlier than previous estimates. The record enabled scientists to predict the consequences of current and projected carbon dioxide levels.
Unless action is taken to restrict the burning of fossil fuels and reduce carbon dioxide emissions, it is projected that atmospheric carbon dioxide levels could reach 600 to 800 parts per million by 2100. The last time levels were this high was 30 to 40 million years ago, with Antarctica also ice-free and the Earth home to giant insects.
The study’s message is clear – the future is now. If action is not taken to curb emissions, the Earth is in for big changes in the environment we live in. The authors of the study believe it’s a call to action and emphasize that human-induced CO2 change is short-lived, it won’t have as big an impact on the climate.