Carbon Dioxide Levels in Earth's Air Reaches New Mark The Mauna Loa Observatory reports that CO2 is now at 415.26 parts per million. That is the first time the gas has reached this high of a level in the planet's atmosphere This is the first time in human history our planet's atmosphere has had more than 415ppm CO2. Not just in recorded history, not just since the invention of agriculture 10,000 years ago. Since before modern humans existed millions of years ago. The news comes shortly after it was revealed human activity is putting over 1 million plants and animals at risk of extinction. The increase in carbon emissions is also associated with climate change, which has been linked to recent extreme cases of weather in the U.S. such as prolonged hurricanes. By 2090, damages caused by climate change could cost America half a trillion dollars annually.