According to recent measurements from the National Oceanic and Atmospheric Administration's (NOAA) observatory in Mauna Lao, Hawaii, carbon dioxide emissions have finally passed the dreaded threshold that everyone's been warned about. For the first time in recorded human history, levels of carbon dioxide surpassed 400 parts per million (ppm); a phenomenon that has not graced this planet for millions of years.
"That increase is not a surprise to scientists," said NOAA senior scientist Pieter Tans from Boulder, Colo. "The evidence is conclusive that the strong growth of global CO2 emissions from the burning of coal, oil, and natural gas is driving the acceleration."
Carbon dioxide has gained a reputation as the most important player in our planet's rising temperatures. The heat-trapping gas doesn't just dissipate - it cycles through our atmosphere and oceans over thousands of years. And it's not just the gas's persistence that has earned it the mantle of "global warming problem child," it's also the rate at which it's levels are increasing.
Carbon dioxide rose at an average of 0.7 ppm into the late 1950's. It now increases at an average of 2.1 ppm, causing much concern. Just before the Industrial Revolution, the level of carbon dioxide stood at 280 ppm, and for the last 800,000 years, the levels swung between 180 and 280 ppm. It is estimated that the threshold of 400 ppm has not been reached in three million years.
"There's no stopping CO2 from reaching 400 ppm," said Ralph Keeling. "That's now a done deal. But what happens from here on still matters to climate, and it's still under our control. It mainly comes down to how much we continue to rely on fossil fuels for energy."
Carbon dioxide may be the most recognizable of our greenhouse gases, but researchers are slowly realizing that such a difficult-to-get-rid-of gas might not be the best problem to tackle first. In an earlier study, scientists proposed that tackling four short-lived greenhouse catalysts - methane, tropospheric ozone, hydrofluorocarbons, and black carbon (a.k.a. soot) - might help us buy more time to more effectively deal with the elephant in the room that is carbon dioxide.