Estimating Carbon Stocks within the Swedish Exclusive Economic zone

Abstract:

Carbon storage in natural environments is an important factor for making both national and global carbon budgets. Presently, only carbon stocks in the terrestrial realm are systematically included in national carbon budgets. The large amount of carbon stored in coastal and marine sedimentary stocks are significant and may occur in the same order of magnitude as the terrestrial carbon stocks. Given the current rate of emissions and the pressing need for international agreements on reducing greenhouse gas emissions, a solid understanding of the different carbon stocks are of great importance for making realistic and useful assessments of national carbon budgets. Recently attention has been drawn to the carbon storage capacity of coastal sediments (Smith et al., 2015; Smeaton et al., 2016; Avelar et al., 2017). It has been shown that many coastal regions have high sediment carbon stocks, particularly in fjords (Smith, et al, 2015). Coastal sediment carbon stocks can also be significant when compared to terrestrial carbon stocks which are normally included in the assessments.

The aim of our project is to produce estimates of the marine carbon stocks within the Exclusive Economic Zone of Sweden along the entire coastline. We will present preliminary carbon stock estimates based on published data on sediment cores together with data from the Geological Survey of Sweden. Semivariograms for bulk density and total organic carbon have been fitted and used for kriging. The resulting rasters form the basis for estimating carbon stocks. For coastal-marine settings we are developing a GIS model of basin shape and bottom type representing the Baltic coast. The purpose of including bottom type in our GIS averaging is to account for soft depositional bottoms with higher carbon accumulation and hard erosional bottoms with no or low accumulation. We aim to produce a data set that show regional differences in carbon stocks along the Swedish coast as well as an estimate of the total carbon stock of the Baltic coast.