Global warming. Conceptual computer artwork of the Earth on fire. It is feared that an increase in greenhouse gases (including carbon dioxide, nitrogen and sulphur oxides, and methane) in the atmosphere will lead to a permanent change in the Earth's climate. A global rise in temperature could melt the polar ice caps and cause severe drought in some areas. Due to the complexity of weather patterns, it could also lead to more severe weather, such as colder winters, excess rain and flooding.