Comparing greenhouse gas levels
Before industrial times began at the end of the 18th century, carbon dioxide in the atmosphere sat at around 300 parts per million. This means that for every one million molecules of gas in the atmosphere, 300 were carbon dioxide.
In February this year, atmospheric carbon dioxide reached 414.1 parts per million. Total greenhouse gas level – carbon dioxide, methane and nitrous oxide combined – reached almost 500 parts per million of carbon dioxide-equivalent
Carbon dioxide is now pouring into the atmosphere at a rate of two to three parts per million each year.
Using carbon records stored in fossils and organic matter, I have determined that current carbon emissions constitute an extreme event in the recorded history of Earth.
My research has demonstrated that annual carbon dioxide emissions are now faster than after both the asteroid impact that eradicated the dinosaurs (about 0.18 parts per million CO2 per year), and the thermal maximum 55 million years ago (about 0.11 parts per million CO2 per year).
The next mass extinction has begun
Current atmospheric concentrations of carbon dioxide are not yet at the levels seen 55 million and 65 million years ago. But the massive influx of carbon dioxide means the climate is changing faster than many plant and animal species can adapt.
A major United Nations report released last year warned around one million animal and plant species were threatened with extinction. Climate change was listed as one of five key drivers.