No Turning Back As Earth Permanently Passes CO2 Threshold


Robin Andrews

Science & Policy Writer


It's a brave new world. rdonar/Shutterstock

Under the imperfect but groundbreaking Paris agreement, now ratified by the world’s two largest carbon emitters, it’s hoped that the world will not warm by more than 2°C (3.6°F) by 2100. Sadly, we have registered so many high-temperature records this year alone that it’s looking doubtful that this will be achieved – and it appears that the most ominous record has just been broken.

According to data provided by the National Oceanic and Atmospheric Administration (NOAA), the concentration of atmospheric carbon dioxide hasn’t dropped below 400 parts per million (ppm) all September. During this time of year, climatological processes normally render the atmospheric concentration quite low, so the fact that this happened at all is astonishing.


It seems then that 2016 will be the year that the world permanently passed the 400ppm threshold. Although this value is mostly symbolic, it does represent just how significantly we’ve altered the climate.

“Is it possible that October 2016 will yield a lower monthly value than September and dip below 400ppm?” Ralph Keeling, a professor at the Scripps Institution of Oceanography, wrote in a blog post accompanying the ignominious milestone. “Almost impossible.”

“By November, we will be marching up the rising half of the cycle, pushing towards new highs and perhaps even breaking the 410ppm barrier,” he added.

Pre-industrial levels were around 280ppm, which means that since the late-18th century, there’s been an unprecedented 43 percent increase in atmospheric carbon dioxide. This has led to a warming rate that’s 10 times faster than what would be naturally expected during an interglacial period.


Spare a thought for the oceans, though, the largest carbon sink on the planet. There may be a lot more carbon dioxide in the atmosphere, but the oceans have already absorbed so much that if they were to expunge it all back out overnight, the world would warm 360 times faster than the natural rate.

The daily (yellow circles) averaged carbon dioxide values as measured from atop Mauna Loa, Hawaii. NOAA

The concentration of atmospheric carbon dioxide will only climb at a faster rate from this point onwards. The Paris agreement will take some time to kick in, and emissions will still climb for several decades by most expert’s calculations. Several have concluded that by 2030, there will be so much atmospheric carbon dioxide pumped into the sky that we would have locked the planet into warming by 2°C (3.6°F) before the century’s end.

In fact, we’re also currently on track to double the pre-industrial concentration to 560ppm by 2100. One study suggests this could induce a further warming of up to 9°C (16.2°F). This will result in more powerful natural disasters, increased conflict, less food, sunken cities, and the collapse of the world economy – just to give a little preview into the upcoming pandemonium.


It’s an avoidable problem, of course. The US alone could be powered by a wind farm the size of Rhode Island, Indonesia could be fueled by volcanic heat, and a mix of renewables and nuclear power could supply almost any nation with its energy needs. Efforts have picked up pace, but it’s difficult to change centuries-old energy generation infrastructure overnight.

For many reasons, 2016 is turning out to be an incredibly worrying year. Now it’s looking certain that it will also be the hottest year on record, one that’s being smothered in carbon dioxide emissions.

Hopefully the next president of the US won’t think climate change is an international conspiracy, because if they do, you can all but guarantee that the unstable ship we’re on will sink in the ever-rising waters.

Look at that world heating up. Expect more of the same for the next few decades – at least. NASA


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  • climate change,

  • global warming,

  • greenhouse gases,

  • record,

  • concentration,

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  • barrier,

  • 400ppm,

  • atmospheric carbon dioxide,

  • threshhold