World Passes 400 PPM Threshold permanently

778September 2016 now marks the point at which the carbon dioxide levels failed to drop below the 400 parts per million (ppm) measurement for the first time ever. The Mauna Loa Observatory has been the official recorder of the the levels of carbon dioxide because they are located far out in the Pacific on Hawaii far from the centres of industrialisation, hence are ideally placed to make such atmospheric measurements. As explained on their website …

Mauna Loa Observatory (MLO) is a premier atmospheric research facility that has been continuously monitoring and collecting data related to atmospheric change since the 1950’s. The undisturbed air, remote location, and minimal influences of vegetation and human activity at MLO are ideal for monitoring constituents in the atmosphere that can cause climate change. The observatory is part of the National Oceanic and Atmospheric Administration (NOAA) – Earth System Research Laboratory (ESRL) – Global Monitoring Division (GMD).

September is the month when the carbon Dioxide levels are at their seasonal lowest because the summer plant growing season has peaked and so they are no longer sucking up carbon dioxide. This September low is above the 400 ppm mark.

Is 400 ppm really a big deal?

Perhaps the best way to answer that comes in two parts.

The first is to look at the specific measurements taken by the Mauna Loa Observatory between 1960 and now. Here is a chart from their website that sums up that data in one rather startling graphic …

co2_data_mlo-2In the above you can see the seasonal variation, and so while we reached the 400 ppm mark for the first time in May 2013, this month now marks the first time ever that the natural variations failed to fall back below 400 ppm.

The second bit of information that perhaps might then help you to grasp how truly disturbing such a measurement can be is the knowledge that Planet Earth has in the past experienced high Carbon Dioxide levels like this. Back in 2013 Scientific American ran an article that laid out the evidence entitled “Ice-Free Arctic in Pliocene, Last Time CO2 Levels above 400 PPM“. During the Pliocene, roughly about 3.6 million years ago, the levels of Carbon Dioxide were in the range of about 380 to 450 parts per million. There is a deep lake in Russia, Lake El’gygytgyn, that is about 60 miles inside the Arctic circle. What makes it unique is that it has never been covered by glaciers, hence we have a continuous climate record contained within its sediments …

After getting the sediment core out of the lake, the scientists analyzed it in two parts. They published the results of their first analysis, looking at the last 2.8 million years, last summer.

The second part of the story involves the part of the core from 2.2 million to 3.6 million years ago. In their analysis, the scientists found this part of the sediment core contains enough fossil pollen and other signs of vegetation to bolster the idea that the mid-Pliocene Arctic was warm and forested, making it highly unlikely that the region had year-round sea ice at that time, Brigham-Grette said.

“If you have a forested Arctic with five different kinds of pine trees … you can’t really have perennial sea ice at the same time,” she said.

Other sediment cores from around the Arctic have also found signs of consistent vegetation during the Pliocene


The Guardian article on the passing of this milestone lays out the rather stark consequences we now face …

The carbon dioxide we’ve already committed to the atmosphere has warmed the world about 1.8F since the start of the industrial revolution. This year, in addition to marking the start of our new 400 ppm world, is also set to be the hottest year on record. The planet has edged right up against the 1.5C (2.7F) warming threshold, a key metric in last year’s Paris climate agreement.

Even though there are some hopeful signs that world leaders will take actions to reduce emissions, those actions will have to happen on an accelerating timetable in order to avoid 2C of warming. That’s the level outlined by policymakers as a safe threshold for climate change. And even if the world limits warming to that benchmark, it will still likely spell doom for low-lying small island states and have serious repercussions around the world, from more extreme heat waves to droughts, coastal flooding and the extinction of many coral reefs.

To highlight the issue the website lays out the case for a push to get us back down to 350 ppm.

We can either take decisive action now or face the consequences. If we do nothing and the world does continue to warm, then longer term we face the ice in both Greenland and also the Antarctic continuing to melt and raising sea levels.

Side Note: sea level rise is not the only concern, it just happens to be one that illustrates how dire things could get.

OK, so sea level will rise a bit, so what.

There is enough ice in Greenland to raise sea levels by about 6 meters. Antarctica however is different, there we find enough ice to rase sea levels by as much as 60 meters. In other words, doing nothing will in the long term lead to the loss of all costal cities and would also lead to a huge displacement of the human population.

This is not going to happen quickly, but it is the direction we are currently heading in. The 20th century average for sea level rise was 1.7 mm per year. That however has accelerated to 3.3 mm between 1993 and 2009.

The passing of the 400 ppm milestone is perhaps a rather stark reminder that doing nothing is really not a viable option and underlines the fact that the ratification of the Paris Agreement on Climate Change is perhaps the most important decision that we as a species must take.

Additionally, if you are also tempted to think that perhaps the most important issue of our day at this moment is Trump, then you might actually be right. This is perhaps because if elected, then it is distinctly possible that he would completely scupper the Paris Agreement by sticking to his promise to pull the US out of it, and also get the US back into burning coal and oil in a big way.

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