Estimates from Question 4 show that, if the world continues to consume fossil fuels at the pace observed in 2015, then we will emit ~ 3000 - 4000 gigatonnes (Gt) of CO2 into the atmosphere between the Industrial Revolution and 2050, leading to a temperature increase relative to global temperatures before the Industrial Revolution.
The estimate of ~3000 - 4000 gigatonnes of CO2 , however, represents the amount of emissions, not the amount that actually becomes stored in the atmosphere. In lecture, we will discuss how natural carbon sinks, such as plants/soils, oceans, and the lithosphere, can remove 5.2 gigatonnes of carbon (carbon, not carbon dioxide) from the atmosphere each year. That means 5.2 gigatonnes of our carbon emissions (not carbon dioxide emissions) can be removed and stored in soil, the oceans, and the lithosphere.
We can use a modified version of the cumulative consumption equation above to estimate the cumulative growth in atmospheric carbon (not carbon dioxide) due to the consumption of fossil fuels:
Cumulative carbon storage = [(N0/r)*(ert - 1)] - (t*D)
where N0 = carbon emissions in initial year (gigatonnes)
r = annual growth rate in carbon emissions
t = time in years
D = rate at which natural carbon sinks remove atmospheric carbon (gigatonnes/year)
Use the 2016 statistics (below) from our textbook to calculate how many gigatonnes of carbon will be stored in the atmosphere by 2050. This is the same as estimating the size of the atmospheric reservoir of carbon in 2050. Assume that the rate of carbon removal into natural carbon sinks remains constant. Also assume that we continue to burn fossil fuels following the pattern observed in 2016. In other words, let's assume a "business-as-usual" model for consuming fossil fuels.
Amount of carbon in the atmosphere before 2016 = 850 gigatonnes
Carbon emissions in 2016 = 10 gigatonnes
Annual growth rate in carbon emissions = 0.003
Hint: The time span from 2016-2050 contains 35 years.
Please type the answers out in the following format:
The size of the atmospheric carbon reservoir in 2050 = XXXX gigatonnes.