Evidently, 410 parts per million is the new normality. That's the average level of carbon dioxide concentrations reached at the Mauna Loa Observatory in Hawaii last April. The only other time that CO2 levels reached that maximum number in Mauna Loa was in April of last year. To put 410 ppm in perspective, according to NASA, the Earth's CO2 levels ranged from 200 ppm to 280 ppm for hundreds of thousands of years, until very recently. But 410 ppm is unprecedented.
During the middle Pliocene epoch, about three million years ago, CO2 remained around 400 ppm for a long time. The Earth was also much warmer than it is now, and sea levels were about 66 feet higher than what they are today. So, why is not that the case now? Scientists warn that this is not the case yet. Our contemporary rise to 410 ppm has happened extraordinarily fast, in the blink of an eye, geologically speaking. For what it's worth, the Trump administration ordered NASA to cancel its carbon monitoring program. It is a purely symbolic gesture, since a large number of private entities will continue to track the CO2 levels of the planet.