Abstract: The role of grasslands in the sequestration of atmospheric Carbon represents an important benefit of extensive livestock systems based on permanent grasslands.  The accurate modelling of such systems is key to understanding their potential in mitigating GHG emissions, and this in turn relies on access to high quality data.  Here, the availability of Carbon sequestration data for EU grasslands is investigated, using information gathered from reviews of journal papers and EU project outputs.  The challenges involved in providing information on datasets to modellers are discussed, and the next steps in the gathering and sharing of meta-data are defined.