According to this article, climate change and high rates of global carbon emissions focus attention on the need for high-quality monitoring systems to assess how much carbon is present in terrestrial systems and how these change over time. The choice of which system to adopt should be guided by good science. There is a growing body of scientific and technical information about ground-based and remote sensing methods of carbon measurement. The adequacy and comparability of these systems have not been fully evaluated. A systematic review will compare methods of assessing carbon stocks and carbon stock changes in key land-use categories.