Surabaya is a coastal city that is still developing. Like other developing cities, Surabaya highly suppresses the mangrove forest for the residential, industry and other areas. Mangrove forest as a conservation land has an essential function as an oxygen source for people in Surabaya and it absorbs CO2. Mangrove forest functions to decrease the impact of global warming and maintain the coastal ecosystem sustainability. This research aimed to 1) Map the dynamics of temperature in Surabaya during the last twenty years (1996-2016) by using Remote Sensing and GIS. 2) Examine the ability of mangrove forest in absorbing CO2 and heat energy in decreasing the impact of global warming in Surabaya. The research results showed that 1) based on the analysis result of temperature surface extent, the temperature has changed since 1996 up to 2016. The trend of the temperature change can be classified into three surface temperatures which are low, moderate and high. The low temperature with the category of 210-300C had a different trend. Every year, the trend of the area extent of which surface temperature was highly categorized was 310-420C. The trend was highly increasing in the period of 2006-2016. Such condition showed that, in 2016, Surabaya had a high temperature increase. (2) There was a correlation between mangrove forest change and the temperature change; the content of CO2 in the mangrove, vegetation and water areas was reduced and it increased in the areas used for buildings such as factory, residential, road and other. The content of CO2 in the air of Surabaya showed the distribution grouping in the “high” and “extremely high” categories. The high category was 27.5% and the extremely high category was 67.5%. The sample point in each moderate and low category was around 25%.