Climate Change

We are living in a 400 ppm world, maybe permanently

The CO2 levels in earth's atmosphere have permanently crossed the dangerous 400 ppm mark

 
By DTE Staff
Last Updated: Thursday 29 September 2016
Almost all weather stations around the world have registered carbon dioxide levels above 400 PPM in September. Credit: Eric Schmuttenmaer / Flicker
Almost all weather stations around the world have registered carbon dioxide levels above 400 PPM in September. Credit: Eric Schmuttenmaer / Flicker Almost all weather stations around the world have registered carbon dioxide levels above 400 PPM in September. Credit: Eric Schmuttenmaer / Flicker

Earth's atmospheric carbon dioxide levels have crossed the 400 ppm mark, and this time it is unlikely to come below that level. The last time the planet had 400 ppm for a long time was 3 million years ago. It’s a grim reminder that we are moving further from the climate we have known and thrived in.

According to scientists, 2016 will be the year that carbon dioxide passed the symbolic 400 ppm mark, “never to return below it in our lifetimes”. Even if all anthropogenic emissions stop tomorrow, the greenhouse gases that have already been spewed are still trapped in the atmosphere and they can stay in the upper atmosphere for centuries before they break down.

Ruling out the possibility of the ppm level dipping below 400 ppm in October, Ralph Keeling, the scientist who runs the Scripps Institute for Oceanography’s carbon dioxide monitoring programme, wrote in a blog post, “The monthly value for October will therefore almost certainly also stay above 400 ppm and probably will be higher than 401 ppm.  By November, we will be marching up the rising half of the cycle, pushing towards new highs and perhaps even breaking the 410 ppm barrier.”

What’s more worrying?

September is usually the month when carbon dioxide is at its lowest level. It is considered the ‘freshest’ month after plants had utilised the summer to grow and suck CO2 out of the atmosphere. It is only during the fall that plants shed their leaves and release the stored carbon dioxide back into the atmosphere. At Mauna Loa Observatory, the major site for monitoring carbon dioxide, the levels remained above 400 ppm throughout September. Almost all weather stations around the world have registered carbon dioxide levels above 400 ppm this month.

Signs of warmer times

Crossing the critical threshold doesn’t come as a surprise to all those who have been following the trends since 2013 when our confidence in emission reduction measures suffered a quake. In 2015, the world received another alarm when PPM level breached the 400 mark once again.

The signs of rising CO2 level in earth’s atmosphere were for all of us to see in the form of polar ice melting and greening of the Greenland. In June 2016, Antarctica—the most remote continent on earth—recorded CO2 level of 400 ppm for the first time in four million years.

The carbon dioxide we have already released into the atmosphere has warmed the world by about 0.8°C since the start of the industrial revolution. Apart from marking the start of our new 400 ppm world, 2016 is going to be the hottest year on record. When indicators are so grim, the world leaders get a sense of the ginormous challenge they are up against—avoiding 2°C of warming.

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