Enhanced Terrestrial Carbon Sink Inferred from O2/N2 Ratio Compared to Dynamic Global Vegetative Models

Measurements of the O₂/N₂ ratio taken since the early 1990s have shown a slight decline in the abundance of atmospheric O₂. The main reason for this loss is the combustion of fossil fuels which consumes O₂ to produce CO₂. Given this relation, one would expect CO₂ to rise at the same rate as the decline in O₂. However, this is not observed due to the solubility of CO₂ in the world's oceans and plant photosynthesis outpacing respiration resulting in increased biomass production (i.e. the world's ocean and terrestrial carbon sinks). We will use measurements of atmospheric CO₂ and the O₂/N₂ ratio from the Scripps Institute, anthropogenic carbon emissions by fuel type and their O₂ consumption factors, a term we calculate for ocean outgassing of O₂, and an estimate for the relationship between photosynthesis and respiration to compute the partitioning of the world's ocean and terrestrial sinks. We will then compare these results to archived values of the global land (terrestrial) sink from Dynamic Global Vegetation Models (DGVMs) and archived ocean sink values from Global Ocean Biogeochemistry Models (GOBMs). Our preliminary results indicate that DGVMs have underestimated the strength of the terrestrial carbon sink, whereas our estimate of the ocean sink appears to be in good agreement with that of GOBMs. Finally, we will analyze multiple active sampling stations individually to see if we can discern any hemispheric gradient in either the trend or cumulative ocean and terrestrial carbon sinks.