Usually a word or concept can be defined in just one sentence. A definition essay, however, needs to be several paragraphs. Therefore, the definition must be extended to include examples, details, personal experience, description, causes, effects, analysis, etc.
Global Warming Causes More Hurricanes. It could be that the tropical oceans will become warmer with a simultaneous decrease in upper atmosphere temperature, which will cause stronger convection, which will help tropical storms to become more organized and stronger so there will be stronger hurricanes.
However, the effect that global warming will cause on earth are extremely serious. There are many effects that will happen in the future if global warming continues. That includes polar ice caps melting, economic consequences, warmer waters and more hurricanes, spread of diseases and earthquake.