Earth Passes Global Warming Threshold

It seems that along with being the hottest year on record, 2016 will also set another ominous record. The US National Oceanic and Atmospheric Administration has released a troubling report detailing how atmospheric CO2 levels did not drop below 400 parts per million (ppm) all September – a time of year when natural climatological processes normally reduce atmospheric carbon to yearly-low levels.
The report all but confirms that that atmospheric levels of carbon dioxide are now permanently passed this threshold –an important milestone in climate change because it effectively means that Earth has passed a tipping-point and become “locked” in a irreversible greenhouse effect.
The threshold was first reached in May of 2013, when an NOAA monitoring station in Mauna Loa, Hawaii registered a monthly average above 400ppm; atmospheric carbon dioxide concentrations in the northern hemisphere have a large seasonal cycle, however, so each year since these levels have dipped below 400ppm. In the southern hemisphere, this cycle is far less pronounced, and earlier this year a station in Cape Grim, Australia reported a reading of 399.9ppm on May 6. Just a few weeks later that month on May 23, the South Pole Observatory reported a reading above 400ppm.
These measurements show just how much humanity has affected our environment since the start of the industrial revolution in the late eighteenth-century. Pre-industrial levels were around 280ppm, which means that in the last 140 years there has been a 43% increase in levels of atmospheric carbon dioxide. For context, ice-core samples show that the last time so much CO2 in the atmosphere was in the air was during the Pliocene epoch over 3.5 million years ago, when global temperatures were about 4°C higher (up to 8°C warmer at the poles) than they are today and the virtually ice-free arctic circle was covered in forests – this might sound pleasant, but that lack of ice means that sea levels were up to 40 meters higher than the present day.
Even with last year’s Paris Climate Accords, which were ratified in the hope that emissions could be cut enough to avoid warming the world by more than 2°C by the year 2100, experts say that emissions will continue to rise for the next several decades at least; several studies have concluded that by 2030, we will have pumped so much carbon dioxide into the atmosphere that we will have ensured that these goals will not be reached by the start of the twenty-second century –in fact, we are currently on track to double pre-industrial levels to 560 ppm by that point.
It simply cannot be overstated how urgent this situation is –even if drastic measures were taken to cut all greenhouse gas emissions tomorrow, we are still on track for more powerful natural disasters, increased levels of conflict over food and water, sunken coastlines and cities and the possible collapse of the world economy. We have already seen some of these consequences in the form of extreme heat waves and flooding which have brought about chaos and conflict in the affected regions (the 2010 Syrian drought which lead to its current state of civil war being a dramatic example), and these problems will only get worse unless increased measures are taken not only to curb emissions, but to actively reduce levels of greenhouse gasses in the atmosphere.
“We are creating a prehistoric climate in which human societies will face huge and potentially catastrophic risks,” said Bob Ward, policy director at the Grantham Research Institute on Climate Change at the London School of Economics, in an interview with The Guardian. “Only by urgently reducing global emissions will we be able to avoid the full consequences of turning back the climate clock by 3 million years.”