The oceans, the land, the air, the plants and animals, and the energy from the Sun all affect each other to make everything work together.
The Earth's climate is getting warmer at a faster rate due to human activities, such as industry and forest clearance. Scientists believe that climate change will make existing hazards such as rising sea levels more intense, and increase the frequency of extreme weather events such as storms and droughts (especially on the east coast of New Zealand).
As the temperature of the oceans warm, each water molecule expands a tiny amount. Multiply each tiny expansion over vast oceans and it all adds up, causing sea levels to rise. And ice caps and glaciers are melting more quickly because of rising temperatures also adds to sea level rise.
Even a small increase in the sea level means that any waves generated by a storm surge or tsunami on our coast is going to be higher, damage more of the coastline and come further inland.