The Mauna Loa Observatory in Hawaii keeps an eye on our atmosphere. According to the National Oceanic and Atmospheric Administration (NOAA), it is the oldest continuous monitor of carbon dioxide levels within the atmosphere on Earth. In fact, it's been in the game since 1958. On May 11, its instruments found something that even it had never seen before.
We wish it was better news.
For the first time, Mauna Loa recorded CO2 levels at 415 parts per million (ppm). Not only is this a record high in the 61 years that the site has been watching our skies. According to their records, this is the highest level in at least 800,000 years.
800,000 years? How do they know?
Okay so first off: clearly there weren't any atmospheric observatories back in 800,000 BCE. So how can the experts at the NOAA be so sure?
Thanks to air bubbles trapped within ice.
When ice forms, air can become locked inside. By dating the surrounding ice, scientists can analyze this trapped air to get an idea of what the atmosphere was like when it froze. It's brilliant science, but the message that it's telling us is far from shiny. So what does it exactly mean?
Has Earth ever been here before?
Parts per million is a unit that measures concentration. (As in, how much of something is in something, not how well a person can study for an upcoming math test...)
So when a scientist says that CO2 levels are at 415 ppm, it means that if you could somehow divide a cube of atmosphere into a million pieces, 415 of them would be pure carbon dioxide.
If you're thinking that 415 out of one million doesn't seem like a lot, well, most of the time, it's not. But the fact that it's been nearly one million years since we last saw this amount of CO2 in our air is a cause for concern. Relatively speaking, this is how scientists believe that our CO2 levels shake out during different periods in prehistory.
During the Ice Ages, the average was around 200 ppm—low carbon levels meant a much colder planet, half covered in ice. Typical interglacial (in-between ice age) periods have been at 280 ppm. That's kind of where we should be now. But since humanity started burning fossil fuels intensely, that number has been rising at around 2.5 ppm a year.
You might be asking yourself: Has the Earth ever been at 415 ppm before? The answer is yes. But it's been a while.
Paleoclimate scientists guess that you'd have to go back around 3 million years, at least. During this time, the world's ice caps were much smaller than today, sea levels were higher, and the planet was hotter. Scientists are presenting these levels as evidence that the need for green innovations is an important one indeed.