In the fourth climate change assessment report, IPCC said: “Global warming is an indisputable fact.” And it was owing more than 90% to human activities. But NIPCC and some scientists insist that temperature variation is a normal natural fluctuation. Surface temperature variation of the planet is mainly affected by solar activity. Is human activities the really reason for global warming? To answer this question, we should first of all conduct a comprehensive study of carbon emissions due to human activities; then establish models to study carbon cycle mechanism of the terrestrial ecosystem process so as to clarify the relationship between global warming and carbon emission. Through the study of carbon cycle models in terrestrial ecosystem, and after figuring out carbon sources and emission computing methods in different spatial scales, this paper proposes a carbon emission spatial distribution simulation model which is simple in structure and widely in applicability by mainly using the methods of population data specialization, i.e., carbon emission spatial distribution simulation model based on population and land. After clarifying the application requirements and proposing the theoretical model, this paper designs the architecture of system, an SOA structure of four coverages that can be integrated into the digital city platform and can interact with other application systems. At last, the afore-mentioned theoretical model is realized and a prototype system developed. By using the system, multi-year of carbon emission spatial distribution has been simulated around the whole world, such as China and USA.