Global warming is, in simple terms, the earth's climate increasing in temperature. As this will result in sea temperatures rising, it leads to high-intensity hurricanes and increase in number of hurricanes. A hurricane is caused by evaporation of warm seawater. Climate change increases the warmth of seawater. As a heated environment causes ice caps to melt, resulting in sea levels rising, the chance of coastal surge being amplified increases.
Hurricanes draw their energy from deep below the ocean's surface and increased temperature means that there is more energy and it is even stronger.