You may have missed it, but this past Tuesday was a day like no other:
On Tuesday, the Mauna Loa Observatory recorded its first-ever carbon dioxide reading in excess of 410 parts per million (it was 410.28 ppm in case you want the full deal). Carbon dioxide hasn’t reached that height in millions of years. It’s a new atmosphere that humanity will have to contend with, one that’s trapping more heat and causing the climate to change at a quickening rate.
For comparison purposes, in 1958, when record-keeping began at Mauna Loa (the world’s marquee observatory for carbon dioxide emissions), the reading was 280 ppm. By 2013, we had passed 400 ppm. The last time the level of carbon dioxide was that high, modern humans did not exist.
A 2011 study in the journal Paleoceanography found that atmospheric CO2 levels may have been comparable to today’s as recently as sometime between 2 and 4.6 million years ago, during the Pliocene epoch, which saw the arrival of Homo habilis, a possible ancestor of modern homo sapiens, and when herds of giant, elephant-like Mastadons roamed North America. Modern human civilization didn’t arrive on the scene until the Holocene Epoch, which began 12,000 years ago.
This March marked the 627th month in a row of warmer than normal temperatures. In other words, if you were born after December 1964, you’ve never experienced a month of cooler temperatures than average on this planet.
Since 2013, readings in the low 400’s have been the norm. The jump to 410 ppm-- in just four years-- suggests that by mid-century we will be seeing levels of carbon dioxide in the atmosphere that have not existed in 50 million years, according to a study released two weeks ago. At that time, known as the Eocene, palms and crocodiles inhabited the Canadian Arctic and there was virtually no permanent ice on the planet.
Projecting further, based on current levels of fossil fuel consumption, the capacity of the Earth to support human life eventually ends:
...Stretching current carbon dioxide emissions trends into the more distant future means the planet could hit 2,000 ppm by 2250.
Coupling that with increases to the sun’s energy — a natural process that’s been happening for millions of years as hydrogen is converted into helium via fusion — would push the climate outside the bounds of anything the planet has likely seen in 420 million years. In all likelihood, that would make the planet uninhabitable for humans.
That would take us back to the Silurian period, a time before land plants expanded on Earth to create a habitable planet.
The most common life form of life at that time were trilobites and brachiopods, and there was no pressing need to discuss or “debate” the effects of human-induced climate change.