CO2 and Biomass

Could the increase in CO2 be due to the reduction in biomass such as further depletion of the rain forest and not caused by fossil fuel use?

This uncertainty of land use change emissions is the highest of any flux component of the global carbon budget. The reduction in biomass and change in land use does have an effect on the CO2 content, but the question is how much? and in what comparison to that of fossil fuels. In Figure 1 you can see a comparison of the last 50 years of CO2 emissions in regards to  land use change and fossil fuel usage.

Figure 1. FF and LUC CO2 Emissions. [1]

                                                                       Figure 2. FF and Deforestation CO2 Flux. [1]

As shown in the two figures above it is apparent that reduction of biomass is having an affect on the CO2 emissions. As shown in Figure 1 that percentage of land use change can cause for up to 10% of the CO2 emissions today. But, while fossil fuel emissions deforestation/land use change use to be similar, the last hundred years have shown major change. The fossil fuel emissions shown in both figures have heavily jumped with industrializing over the world. The fossil fuel emissions of CO2 contribute nearly 6 times as much to the CO2 problem as compared to deforestation. Both are though a major factor in the increase in CO2.

[1] http://www.globalcarbonproject.org/carbonbudget/09/presentation.htm