# Carbon Storage and Sequestration - economic data - Germany

I am using InVEST model for my Thesis on the topic of Carbon Storage and Sequestration in relation to land-use change. However, Iβm facing some issues with

1. Understaing the economic model (viz attached), especially the π πππ’ππ π‘π₯. What does it stand for? I was assuming thatβs itβs a difference in carbon stored now and in the future, but why then this variable is called π πππ’ππ π‘π₯?

2. I was planning to use Stern as a source for my Price of carbon, however I got advised to use data from: https://www.umweltbundesamt.de/sites/default/files/medien/1410/publikationen/2019-02-11_methodenkonvention-3-0_en_kostensaetze_korr.pdf from the table number 1. There are recommendation on climate costs in β¬2016 / t CO2 eq being presented. I am wondering how can I adopt these data so I can use them in my research?

Welcome to the forum! For your first question, you are right that π πππ’ππ π‘π₯ in equation 1 in the userβs guide is the change in carbon stored in a parcel of land π₯ over time. Sequestration refers to change in the quantity of carbon stored, while storage refers to the absolute quantity at a specific time. From the userβs guide, βValuation is applied to sequestration, not storage, because market prices relate only to carbon sequestrationβ.

Regarding your second question: the βPrice/metric ton of carbonβ input is given in currency per metric ton of elemental carbon (not CO2) . Since the data you linked is given in β¬/ton CO2, you would need to convert to β¬/ton C by using the ratio of the masses of C and CO2 (12-ish/44-ish β 0.27), so 1 ton CO2 β 0.27 ton carbon in the form of CO2. The currency unit does not matter to the model, so you can leave it in β¬ and the output will be in β¬.

It looks like in the data you linked, the value of carbon is increasing with time. The βAnnual rate of change in price of carbonβ input can represent this with a small negative value. I did notice that your linked report states, βIn order to use cost rates for years for which no values are indicated in Table 1, we recommend interpolating linearly between the indicated cost rates.β The model only supports an exponential rate of change, so this wonβt be exactly possible. Maybe someone with more knowledge of the details of this model could advise how best to do this

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