The concentration of toxic greenhouse gases in our atmosphere has been growing steadily for the past decade. Leading the charge is carbon dioxide (CO2) which is emitted by fossil fuel combustion and other human activities, and which scientists say is the biggest contributor to climate change.

Now, researchers from the National Oceanic and Atmospheric Association say carbon dioxide levels have breached a milestone that many fear could be the point of no return. For the first time in history, concentration of carbon dioxide in the atmosphere of Barrow, Alaska, reached 400 parts per million (ppm) this spring. According to NOAA measurements, the first time a monthly average measurement for the greenhouse gas attained the 400 ppm mark in a remote location. Researchers say it’s only a matter of time before what’s happening in the Arctic spreads all over the globe.

“The northern sites in our monitoring network tell us what is coming soon to the globe as a whole,” said Pieter Tans, an atmospheric scientist with NOAA’s Earth System Research Laboratory (ESRL) in Boulder, Colo. “We will likely see global average CO2 concentrations reach 400 ppm about 2016.”

Ever since An Inconvenient Truth forced us to acknowledge our part in growing greenhouse gas levels, climate change activists have  encouraged governments to set strict limits on carbon dioxide emissions. Scientists have stressed the importance of reducing global CO2 levels back down to the 350 ppm mark that many scientists say is the highest safe level for carbon dioxide. But world leaders have failed to meet emission reduction goals, busying themselves instead with international commitments that are non-binding and weak at best.

“Turning up the levels of greenhouse gases in our atmosphere is like turning up the dial on an electric blanket,” said Jim Butler, director of the ESRL Global Monitoring Division. “You know it will keep getting warmer, but you don’t know how quickly the temperature will rise, and it can take awhile for the blanket – or the atmosphere – to heat up.”

Readings are coming in at 400 and higher all over the Arctic, reports The Washington Post. “They’ve been recorded in Alaska, Greenland, Norway, Iceland and even Mongolia. It’s been at least 800,000 years — probably more — since Earth saw carbon dioxide levels in the 400s,” Butler and other climate scientists said.

The human race has evolved so far since then. It’s amazing that with all our intelligence and technology, we’re still incapable of ceasing the activities that will lead to our certain extinction. With each ppm gained from this point forward, scientists say it will become impossible to limit global warming to just 2 degrees. Unless we drastically alter the course of our species, and quickly move away from societies driven by fossil fuels, we’re in for a bumpy ride.

“It’s an important threshold,” said Carnegie Institution ecologist Chris Field, a scientist who helps lead the Nobel Prize-winning Intergovernmental Panel on Climate Change. “It is an indication that we’re in a different world.”

Photo Credit: NOAA/Flickr