The polar ice shelves are very important for life on the Earth. Indiscriminate use of fossil fuels and other activities by humans have led to a large increase in the carbon dioxide levels in the atmosphere. This has increased the amount of heat that is absorbed by the Earth due to the greenhouse effect. Rising temperatures have started to melt the polar ice shelves, the result of which can be disastrous for life on Earth.
The ice shelves themselves reflect back a lot of solar radiation. As they grow smaller more heat is being absorbed by the Earth, creating a cycle that increases the rate at which they reduce in size.
One of the prime results of the melting of polar ice shelves is an increase in sea levels. The rise in sea levels would cover a lot of the land that we live on with salt water. Shore lines have been receding around the World and as the problem escalates entire nations like the Maldives would be inundated.
The expansion of the seas also threatens agriculture on a large scale as ground water would become salty and unsuitable for plants. This would also be accompanied by climate changes causing droughts in several parts of the World and floods in others. This would affect biodiversity as species that cannot withstand changes like higher temperatures or absence of sweet water would become extinct.
Humans would have to face a lot of problems too. These include massive relocation as the land gets submerged, shortage of water and food, damage due to climatic effects, etc.