Iraq is facing many important climatic changes today, such as rising temperatures, decreasing precipitation, drought, and desertification. The concept of global warming or climate change refers to the increase in the average surface temperature in the world with an increase in the amount of carbon dioxide (CO2) and methane (CH4), in addition to some other gases in the atmosphere, the most important of which are water vapor and nitrous, these gases are known as greenhouse gases, because they contribute to heating the surface of the earth's atmosphere. This phenomenon is known as global warming. One of the most important reasons that led to the rise in temperature in Iraq and the world is due to the increase in the proportion of greenhouse gases in the atmosphere with the increase in the proportion of (CO2) and (CH4). The research aims to study the chemical behaviour of greenhouse gases (CH4, CO2) and their impact on climate change in Iraq from the period (2003-2017) using the data of the European Center for Medium-Range Weather Forecast (ECMWF)/data source dates back to, Copernicus Atmosphere Monitoring Service (CAMS) ECMWF reanalysis for the global climate and weather. Four study stations were selected (Mosul, Baghdad, Rutba, Basra) to know the behaviour of (CH4), and (CO2), the results showed that the maximum level of CH4 concentration is in the summer during the months (July, August) in all regions of Iraq, the stations showed (Baghdad, Basra) the highest level of CH4 concentration, where was the Baghdad station 183.2ppb, 183.8ppb and the Basra station 184.1ppb, 184.5 ppb, while the minimum level of CH4 concentration appears during the months (March, April, May). For the level of CO2 concentration, the maximum level of increase in gas concentration was recorded during the spring season of May in all regions of Iraq, where it reached a maximum value of 397.1 ppm, in the southern region, while the minimum level of CO2 concentration was recorded in the months (August, September, October). The results also indicated that the level of CO2 concentration in the atmosphere is at a high concentration level during June and for all regions of Iraq, the highest limit was recorded in the southern region about 396.6 ppm.