CO2 red line is crossed

This September has set a new, tragic record for carbon dioxide levels. Change hardly seems possible in the face of such permanently high levels, especially as other negative records are piling up. Elke Bunge reports.

Atmospheric carbon dioxide values are typically at their lowest in September. Not this year. Experts warn that we have now permanently exceeded the symbolic 400 ppm threshold. (Image credit: kris krüg, flickr/Creative Commons)

Atmospheric carbon dioxide values are typically at their lowest in September. Not this year. Experts warn that we have now permanently exceeded the symbolic 400 ppm threshold. (Image credit: kris krüg, flickr/Creative Commons)


Time is running out. At the end of 2015, 195 countries agreed on a new climate agreement in Paris, and for the first time the entire world community has committed itself to taking action on climate change. Just this past week enough countries ratified the agreement, enabling it to come into force early next month.

The agreement puts the blame for climate change squarely on the shoulders of humankind. And it unequivocally states that without far-reaching measures to reduce carbon dioxide and nitrogen emissions worldwide by 2050, Earth’s climate can no longer be saved. But despite the global political momentum and enthusiasm over the Paris climate agreement, dangerous record levels continue to pile up at an alarming rate.

Carbon dioxide threshold passed in September

This September has set yet another tragic record. As a rule, carbon dioxide levels in the atmosphere are at their lowest in September as the vegetation period in spring and summer lead to greater oxygen production, thus reducing atmospheric carbon dioxide.

But in 2016, the monthly carbon dioxide value stayed above 400 parts per million (ppm). The measuring unit ppm indicates the ratio of carbon dioxide molecules to all other molecules in the atmosphere. For the first time since these measurements were record, the greenhouse gas concentrations exceeded this limit, even at the annual minimum. The conclusion: we now live in a world with significantly higher carbon dioxide levels – permanently and irrevocably.

Many tragic records in just a short time

In March 2015, global carbon dioxide levels exceeded the 400 ppm threshold in March 2015 for the first time since climate records began. The measurements came from the National Oceanic and Atmospheric Administration (NOAA).

Now that levels exceeding 400 ppm have also been measured in the “low” period of September, scientists predict that levels will not drop below this threshold in the foreseeable future – and certainly not in our lifetime. Humanity must get used to living in a world with carbon dioxide levels that are higher than they ever were in the last several million years.

2016 will go down in history as the year of negative climate records: spring was the warmest ever recorded, extreme weather events are occurring more frequently, and every singly month this year was the warmest on record. In mid-September, Arctic sea ice reached the second-lowest extent ever measured.

Rate exceeding 2 ppm per year

Measurements from the Mauna Loa Observatory and the Global Greenhouse Gas Reference confirm that the carbon dioxide value in 2016 was permanently above the 400 ppm threshold. Climate scientists describe this figure as a symbolic red line – one that has now consistently been exceeded.

The Mauna Loa Observatory on Hawaii is currently showing a carbon dioxide value of 400.91 ppm. Last year, that value was at 397.31ppm. A decade ago, it was only 378.61 ppm.

“In some ways, 400 ppm is just a number, another milestone that we are blasting past at a rate that is now exceeding 2 ppm per year,” says NASA climate researcher David Crisp. “It brings home the fact that fossil fuel combustion, land use practices, and human activities have increased the CO2 concentration in Earth’s atmosphere.”

Change seems impossible

The consequences of these increased greenhouse gas values have long been evident: the increasingly warmer Mediterranean is leading to greater rainfall and more flooding in Central Europe. In the Pacific Ocean, super typhoons are on the rise. Summers are becoming hotter, drought areas are spreading.

The internationally renowned organisation warns that we must succeed in significantly reducing greenhouse gas emissions if the climate is to be saved for humankind. In this respect, the Paris climate agreement marks a turning point in our humankind’s climate history.

Many around the world hope that the urgency with which countries ratified the agreement will be matched with an urgency to implement meaningful measures to slash our greenhouse gas emissions. All eyes will be on the Mauna Loa Observatory in the months and years to come to see what, if any, impact these measures have.

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