During 2016, the annual rate of atmospheric carbon dioxide increase will have hit a record 3.2 to 3.55 parts per million (ppm). By 2017, the amount of carbon dioxide in the Earth’s atmosphere will be roughly equivalent to concentrations last seen during the Middle Miocene climate epoch (404 to 410 ppm average). In other words, atmospheric CO2 is rising at a record rate and we are hitting levels of this heat-trapping gas that have not been seen in about 15 million years.
Record Rates of CO2 Increase
The world is struggling to make the necessary turn toward reducing fossil fuel-based carbon emissions. Global emissions have plateaued at or near new record highs during the past three years. Conflicts over fossil fuel cuts and transitioning to renewable energy embroil numerous countries. Climate change deniers hold significant power in places like the United States, the United Kingdom, Canada, and Australia. And facing off against those who would defend the harmful interests of what could well be called the most destructive industry to ever inhabit the planet, are a broad group of environmentalists, scientists, concerned citizens, and renewable energy advocates.
(Global carbon dioxide is approaching a level not seen since the Middle Miocene period around 15 million years ago when atmospheric concentrations typically averaged above 405 ppm and global temperatures were 3-4 degrees Celsius hotter than 19th-century averages. Record annual rates of CO2 increase in excess of 3 ppm each year for 2015 and 2016 are swiftly propelling us into a climate state that is more similar to this ancient epoch — a shift that is producing increasingly harmful global consequences. Image source: The Copernicus Observatory.)
As the political turmoil ramps up, it appears that the Earth’s oceans and biosphere are straining to draw in the massive volumes of these gasses that we’ve been pumping out. Annual atmospheric CO2 growth rates for 2015 were a record 3.05 ppm. 2016 appears to be on track to beat that high mark, being likely to see a new annual increase of between 3.2 and 3.55 ppm.
Hot Lands and Oceans Tend to Produce a Carbon Feedback
The previous most rapid annual rate of atmospheric CO2 increase was 2.93 ppm during the strong El Niño year of 1998. Back then, high ocean surface temperatures combined with warming-related wildfires and droughts which spanned the globe to reduce the Earth’s capacity to take in carbon. More carbon was squeezed out of hot soils, burning forests, and warming oceans. Less was drawn down. New record rates of atmospheric CO2 increase were breached.
(Except for a couple of days, all of 2016 saw atmospheric CO2 levels above 400 ppm. Peak values as measured at the Mauna Loa Observatory in May were 407.7 ppm. By May 2017, atmospheric CO2 levels are likely to hit near 410 ppm — a level not seen in about 15 million years. Image source: The Keeling Curve/Scripps Institution of Oceanography.)
Even during the period of heightened heat stress that occurred in 1998, we did not see a year in which annual rates of CO2 increase exceeded 3 ppm. We have never, until 2015-2016, seen a time when there were two back-to-back years of such rapid rates of increase. Similar but worsening heat stress impacts have likely flagged what at first appeared to be an increased rate of carbon uptake from the biosphere during the late 2000s. Ocean heat content is now dramatically greater than during 1998 and this significant warming is likely having at least a periodic impact on the ocean’s rate of carbon uptake. Wildfires are now far more prolific, generating more atmospheric carbon. Droughts are more widespread and these tend to squeeze carbon from the soil. The Arctic is the warmest it’s been in 115,000 years and, as a result, some new Earth system carbon sources are starting to pop up.
Record High Rates of Fossil Fuel Emissions Hitting a Plateau
In the intervening years since 1998, global carbon emissions from fossil fuels have also jumped dramatically. During 1998, yearly CO2 emissions were in the range of 26 billion tons per year. By 2014-2015, these greenhouse gas releases had soared to around 35.8 billion tons per year. Through this period, average annual rates of CO2 increase continued to climb during the 2000s and 2010s.
(Global carbon emission increases stalled during 2013, 2014, and 2015 according to The Global Carbon Project. But despite this recent pause, atmospheric rates of carbon dioxide increase have continued to ramp up. Due to a number of factors, including atmospheric and ocean inertia as well as temperature and saturation stress to global carbon stores, it is likely that significant reductions in carbon emissions from fossil fuels will be necessary to have a marked impact on annual rates of atmospheric CO2 increase.)
According to NOAA, the 1980s and 1990s saw yearly jumps in CO2 at the rate of about 1.5 ppm each year. By the 2000s, this average rate of increase had leaped to about 2 ppm per year. For the first six years of the 2010s, the average rate will likely be around 2.5 ppm per year.
New Records Provide Urgency For Rapid Emissions Cuts
This rate of increase roughly matches the overall rate of increase in emissions. As yet, there is no major global trend sign in the atmospheric CO2 data showing that carbon uptake from the oceans and the biosphere has been significantly curtailed, at least not to the point that it has shown up in the long term global trend. There are, however, widespread signs of stress to the Earth’s carbon storage system, and two years of 3 ppm-plus increase back-to-back is a warning blip on the climate radar.
In other words, these new record rates of CO2 increase are disturbing. If the annual increases do not fall back into the low 2-ppm per year range in 2017 and 2018, it will be an indication that some of the Earth’s ability to draw down carbon has been significantly hampered. If that is the case, then the urgency to draw down emissions is considerably greater.
Hat tip to SmallblueMike
(Note: This post focuses primarily on CO2 as an indicator. Overall CO2e levels will be covered in a separate exploration.)