For the first time in human history, the concentration of carbon dioxide in the atmosphere has reached 400 parts per million (ppm). The arrival at this threshold represents a powerful symbol of the growing human influence on the Earth’s climate.Keep note of those years when you read how Marc Morano (the Tribune-Reviews editorial board's non-scientist, swiftboater go-to "expert" on all matters pseudo-scientific) tries to reassure us all that it's not that big of a deal. For example they quote him with this:
Manmade emissions of carbon dioxide have increased the atmospheric concentration of CO2 from around 270 to 280 ppm in the late 1700s to today’s record high level – a 43 percent increase. Measurements of CO2 trapped in air bubbles from ice cores in Antarctica indicate today’s levels are unsurpassed in at least 800,000 years.
From geology's long-view perspective, current CO2 levels are remarkably low.Considering that "geologic time" tracks things in the millions, tens of millions and hundreds of millions of years, and remembering that the Earth (sorry young Earth creationists, but you're still wrong on this, no matter what your Bible tells you) is 4.5 billion years old, a mere 800,000 years really is a very short time - so it's not surprising that at some point in the Earth's past CO2 levels were higher at some point for some reason during that time.
Still doesn't disprove that we've been polluting the air and now the planet's warming up because of it.
800,000 years is a long time in human standards, though. How long a time?
Take a look:
The last time there was this much carbon dioxide (CO2) in the Earth's atmosphere, modern humans didn't exist. Megatoothed sharks prowled the oceans, the world's seas were up to 100 feet higher than they are today, and the global average surface temperature was up to 11°F warmer than it is now.Now go look at the bullet points the Braintrust wants to reassure you with.
As they're bereft of actual chronological context, they're more or less beside the point. And that's hardly reassuring.