At one point the Aral Sea was Earth's fourth largest lake by surface area. However, starting in the 1960s it began to shrink at unprecedented rates, and nowadays it is so small that most people have never heard of it.

The sea was historically a hub of life in Central Asia. There were fish factories located on the shores of the sea that processed 50 million kg of fish per year, employing nearly 30,000 workers. It was very productive because the water was shallow, warm, and rich with algae. The sea was huge: in 1960 it had a surface area of 68,000 sq km and a volume of 1,100 cubic km.

Then, in the early 1960s, the Soviet government decided to divert water from two rivers that fed the Aral Sea away to be used in irrigation for cotton fields, with the hopes of making a lot of money. However, the canals were built poorly, which meant that much of the water that was being diverted from the sea was also being wasted. Additionally, pollution from the cotton industry polluted the water. The rivers got smaller and smaller, which caused them to stop delivering fish to the sea.

By 2010, the sea had a surface area of only 14,280 square km and a volume of only 98 cubic km. And it has shrunk even more since then. The town of Moynaq went from a thriving fishing town to a ship graveyard, where the hulls of former fishing ships have been left to slowly disintegrate on land that used to be seabed. The few people who still live in the area suffer from poor water quality and a high child mortality rate. Some people have hope that the sea will someday come back, but at this point it seems impossible.

Sample Problems

1. By what percentage has the surface area of the Aral Sea shrunk between 1960 and 2010?

2. What is the average rate at which the surface area has shrunk during that time (measured in square km per year)?

3. By what percentage has the volume of the Aral Sea shrunk between the 1960 and 2010?

4. What is the average rate at which the volume has shrunk during that time (measured in cubic km per year)?