Quote of the Day
All problems become smaller if you don’t dodge them, but confront them. Touch a thistle timidly, and it pricks you; grasp it boldly, and its spines crumble.
— William S. Halsey
My youngest son told me that I needed to watch the new Cosmos series with Neil deGrasse Tyson. I was immediately hooked – it is a masterpiece of scientific exposition for a general audience. I thought the original Cosmos with Carl Sagan was excellent, but the progress in computer graphics during the intervening decades makes the program visually stunning.
I was particularly interested in the part of the program that addressed the rise in global CO2 levels. Dr. Tyson stated that 30 billion tons of CO2 are being added to the atmosphere every year from human-related (i.e. anthropogenic) sources. I thought I would try to confirm this tonnage level using Figure 1, which is an atmospheric CO2 level chart from the National Oceanic and Atmospheric Administration (NOAA).
For thousands of years, CO2 levels stayed at ~280 ppm (Figure 2) because the natural mechanisms of CO2 generation have been in equilibrium with the natural mechanisms of CO2 absorption (Source). Figure 2 shows data from both direct measurements and ice cores. Starting in about 1800 CE, this balance was upset and the atmosphere's CO2 level has been rising ever since. The start of rising global CO2 levels and the beginning of the industrial age (~1800 CE) appear to coincide . CO2 levels are now over 400 ppm and are rising at a rate of over 3 ppm per year – and the rate of increase is increasing.
The interesting aspect of Figure 2 is that we can separate out natural sources of CO2 from anthropogenic content by the carbon isotope content () of the CO2. The burning of organic material releases a much higher proportion of (reference), a proportion that is related to a metric known as δ13C. To understand the δ13C metric, see this Wikipedia article.
According to the USGS, volcanoes release about 250 million tons of CO2 compared to 35 billion tons of CO2 from anthropogenic sources.
Annual CO2 Concentration Rise
2016 started with a level of 404.02 ppm, with the concentration increasing by more than 3 ppm in 2015. I found a table of NOAA data for the annual increase in CO2 levels here. In Figure 3, I plotted the data and fit a linear curve to it. Not only is the CO2 concentration increasing every year, the rate of increase is increasing by 0.00275 ppm/year/year.
Annual Atmospheric CO2 Tonnage Increase
Figure 4 shows my rough enough for the tonnage being released into the atmosphere. It is reasonably close to Tyson's "30 billion tons per year" statement. You will notice a unit called "atm" in the analysis – this stands for a sea-level air pressure of 1 atmosphere or 101,335 Pascals.
My rough calculation shows ~27 billion tons of CO2 per year going into the atmosphere. This is within 10% of Tyson's 30 billion ton figure, so my approximations give results that are pretty close to his figure.
I was able to confirm the statement from Neil deGrasse Tyson that the annual increase in atmospheric CO2 tonnage is ~30 billion tons a year. Since volcanic activity releases ~250 million tons of CO2, the vast majority of the CO2 released into the atmosphere every year is from human sources.