I recall why 2000 was done separately. It is because there is a year 2000 physical cropland layer that goes along with the year 2000 crop harvested area and the mirca data as well. This was also used for the livestock and forestry land rent calculation.
But in general the land type area is determined by the hyde data first. So there may still need to be some special calculation for the year 2000 physical cropland and pasture area (for used by other functions), but the output land area is not based on these year 2000 layers.
In any case, store the needed years for any further calculations during this annual calculation. This includes the year 2000 special data, year 2010 for the carbon data, and the year designated for recalibration.
I recall why 2000 was done separately. It is because there is a year 2000 physical cropland layer that goes along with the year 2000 crop harvested area and the mirca data as well. This was also used for the livestock and forestry land rent calculation. But in general the land type area is determined by the hyde data first. So there may still need to be some special calculation for the year 2000 physical cropland and pasture area (for used by other functions), but the output land area is not based on these year 2000 layers. In any case, store the needed years for any further calculations during this annual calculation. This includes the year 2000 special data, year 2010 for the carbon data, and the year designated for recalibration.