|Ice Caps Melting
What would the effects be of a massive rise in sea level?
The vast majority of the world's great cities are on the coast, including virtually every city with a population of above 10 million. They were built there to utilise the sea by fishing and trading abroad. Many grew because of the size of their harbours.
However, there are disadvantages to being located on the coast. It leaves these cities extremely vulnerable to a rise in sea levels. A rise of just a metre could mean that the ocean flowed into city streets at high tide. A rise of several metres would make holding this water back near impossible without hugely expensive flood defences. A rise of much more than that could mean that low lying area of cities would have to be evacuated. Imagine the consequences of what would happen if sea levels were to rise by more than 55 metres.
New York, Los Angeles, Rio de Janeiro, Sau Paulo, Bombay, Tokyo, Kobe, London and Shanghai, to name but a few, would all be swamped by this rise. Not only cities would suffer: thousands of islands would disappear, which would be especially difficult to evacuate in poor countries. Much of the world's best farmland is below this height and the loss of it could mean massive food shortages around the world. Our already overcrowded world would then have even less space and less food to go around.
What might cause sea levels to rise?
Global warming could potentially cause this massive increase. Global warming is a proven fact, no scientist debates that temperatures are rising. The debate is whether this is caused by greenhouse gasses (like carbon dioxide, methane and CFCs), but this is irrelevant to the ice caps.
Global warming is having a dual effect on sea levels. Rising global temperatures make the sea warmer. As liquids warm they expand. This means that without any more water entering the sea, it is getting deeper. Scientists are already beginning to observe this effect as sea levels start to rise, watched in horror by inhabitants of small islands as the coastline recedes.
The second effect is that the increased temperature will make the polar ice caps (the Arctic and Antarctica) start to melt. As the ice warms, it melts, putting more water into the sea. If all of Antarctica melts sea levels would rise by 55 metres. That is excluding the North Pole and all the glaciers combined. To see the effect melting ice has on water, leave a few ice cubes in a dish of water and watch the water level rise as they melt.
Is there evidence that the ice caps are melting?
Clearly it is vital to research if the ice caps are melting. A large amount of separate research suggests that it is already happening, and the rate of this can only increase if the predicted rise in the rate of global warming occurs. Here is only a small part of the evidence:
· Since the 1950s the Arctic ice sheet has become 40% thinner during the summer and covers 15% less area.
· Arctic temperatures are the warmest for 400 years
· Since the 1960s snow cover has declined by 10%
· In just seven years, Pine Island Glacier, part of the Antarctic ice sheet, has thinned by more than 5 feet.