What first cause of global warming? heaters population growth increasing greenhouse gases. What time it was found the largest contribution to global warming? in the last 50 years in the last 60 years in the last 2000 years. Are there variations of the earth orbit around the sun? Yes, there are. No, there aren't. which greenhouse gases were stabilized? In 2000 years In 50 years In 1950 years. Which the additional heat about for year? Approximately 0.5 º C Approximately 0.4 º C Approximately 5 º C. Does the text happen in that tense? Simple past Simple Present Future.