A good topic for an article on global warming is a comparison of changes in Earth's temperature with the number and strength of storms such as hurricanes, tornadoes and typhoons. Another article topic could study the possible effects of global warming on agriculture.
A more focused article on agriculture and global warming could look at a certain crop, such as rice, and compare its yield in various regions of the world to see how temperatures affect it. While crops grow faster when temperatures are higher, the yield may be lower due to the higher speed of growth. Other possible article topics include investigating the root causes of global warming and the role of carbon dioxide in global warming.