I am not sure I exactly follow, but you can monitor carbon sequestration using gross primary production (GPP) in vegetation.

I think that you can use MODIS data

Yes MODIS has a GPP product. Also you can read this paper that talks about how to estimate GPP: http://www.calmit.unl.edu/people/agitelson2/pdf/2011/2011-RSE-GPP-Peng-et-al.pdf

The first step should be to find biomass of the patch of vegetation and then calculating the carbon stock of the patch, which in most cases ranges from 40-50% of the biomass. For biomass calculation you have to correlate the remotely sensed data with the field -derived patch/stand biophysical variables.

You need to identify tools at your disposal to be able to carry out the study. Will you use ground data from field plots and generalise this with remotely sensed data? In that case you need  field plot data stratified in the variety of forest vegetation types. With carbon/biomass estimates from such plots, satellite images can be used to generalise the carbon zones of the forest and their estimated stocks. Note that you may need high resolution imagery. You may also integrate other tools/techniques like LiDAR to give tree heights or RADAR to estimate forest densities

Thank you all for the help. Am now doing it

Thank you