Global Warming Gas Carbon Dioxide Reaches 400 Parts per Million

Before the industrial revolution took hold in the middle of the nineteenth century, carbon dioxide (CO2) in the Earth’s atmosphere had been relatively stable, according the geological record. Atmospheric CO2 did not stray far from 280 parts for millions (ppm) for thousands of years. Since the 1880s, carbon dioxide has steadily increased in the Earth’s atmosphere, and as of the middle of 2012 stands at a worldwide average of approximately 394 parts per million. In a glimpse of what is coming, carbon dioxide sensing locations in the remote northern reaches of the Earth are now detecting carbon dioxide at 400 parts per million.

According to a May 31, 2012 press release by the United States government agency National Oceanic and Atmospheric Administration (NOAA), the concentration of carbon dioxide in the atmosphere at the Barrow, Alaska NOAA measuring station reached 400 parts per million during the spring of 2012. This marks the first time a monthly average measurement of carbon dioxide gas in the atmosphere was measured at the 400 parts per million level in a remote NOAA measuring location.

Carbon dioxide was measured at the 400 parts per million level at six additional remote northern locations that are part of NOAA’s international cooperative air sampling network at least once during the spring of 2012. These six sites include: a second site in Alaska and others in Canada, Iceland, Finland, Norway, and an island in the North Pacific.

Carbon dioxide measured at the 400 parts per million level at remote northern locations is a harbinger of average global atmospheric carbon dioxide levels reaching 400 parts per million during the current decade. Pieter Tans, an atmospheric scientist with NOAA’s Earth System Research Laboratory (ESRL) in Boulder, Colorado was quoted in the NOAA press release as stating, “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.”

While mid-latitude sites in NOAA’s carbon dioxide monitoring network, such as Cape May, New Jersey, have recorded carbon dioxide in the spring that has exceeded 400 parts per million for several years, such readings were discounted due to the influence that major carbon dioxide producing cities upwind of the sites has on the readings. What makes the 400 parts per million readings in the spring of 2012 from the seven remote carbon dioxide monitoring locations significant is that the remote sites reflect background levels of atmospheric carbon dioxide due to their remote location away from major population centers.

In the short term, worldwide 400 parts per million carbon dioxide probably does not mean a whole lot; however, the long-term implications of reaching this atmospheric carbon dioxide milestone could be catastrophic. Although global warming appears to have taken a breather over the past decade and a half, the leveling off of average global temperatures is likely just a temporary phenomenon that is due to other climate influences from the sun’s radiance level to natural temperature oscillations in the Pacific ocean.

While the Earth seems to be managing the steady increase in atmospheric carbon dioxide relatively well so far (although the effects of this increase may not be felt for many decades to come), there are concerns that passing the 400 parts per million atmospheric carbon dioxide threshold will bring the Earth’s atmosphere closer to a tipping point at which global warming accelerates rapidly with dire consequences for mankind and other creatures on Earth. What is concerning is the possibility that rapid global warming could occur faster than many people believe is possible, if global warming due to atmospheric carbon dioxide causes the Earth’s atmosphere to warm enough to release enormous deposits of frozen methane (CH4) that are stored in the permafrost above the Arctic Circle and in frozen methane ice, known as methane hydrate, underneath the floors of the oceans throughout the world (see: How Methane Gas Releases Due To Global Warming Could Cause Human Extinction). Once the tipping point is reached, the massive release of frozen methane into the Earth’s atmosphere could occur over a matter of just decades, which could result in a far warmer world much sooner than many people believe is possible since methane is a potent global warming gas, with likely negative impacts for all living beings on Earth.

As can be seen in the NOAA Earth System Research Laboratory animation of carbon dioxide levels for the past 800,000 years below, atmospheric carbon dioxide levels are currently well above where they have been over the 800,000 years, according to the geological record. What is a “safe” level of worldwide atmospheric carbon dioxide? That question is highly debatable since the outcome of increasing atmospheric carbon dioxide is unknown and is subject to considerable debate. However, it appears that keeping atmospheric carbon dioxide to a level that maintains a global atmospheric temperature below the threshold at which frozen methane deposits are released would be a prudent goal for mankind to pursue. Exceeding the 400 parts per million level of worldwide atmospheric carbon dioxide later this decade continues a troubling trend which brings the world closer to the potential to reach a global warming tipping point in which global warming accelerates rapidly as the potent greenhouse gas methane is liberated from the frozen state that it has been in for millions of years.