The tropical rainforests are essential for sustainable development of earth's ecosystem. The rainforests are rich storehouse of biodiversity, natural pharmaceutical products, source of sustained water resources and manage microclimate of their region. The forest regimes in Amazonian, Congo basin and South East Asian forest regions are under constant threat of degradation. The carbon dioxide concentration in the earth's atmosphere has reached the highest ever seen by the human beings to 400 ppm level and mean surface temperature of earth has increased by 1°C in last 50 years. This study explores statistical relations for rainforest remaining in the earth and carbon dioxide concentration in the earth's atmosphere as function of widespread human farm activities such as soya bean, corn and palm oil production as factors. The response surface methodology is used to analyse data from year 2000 to 2013 which shows that rate of world tropical rainforest degradation and CO2 concentration in the earth's atmosphere increases with increase in world soy, corn and palm production and mathematical models predicting these relations were developed.