Blue Planet Prize Story

The Resilience Alliance (RA) has a database that shows a wide range of cases in which systems were unable to return to their original states. Two cases are explained here using information from the database.

Resilience Alliance - Thresholds Database

Case 1. Easter Island

Easter Island is a territory of Chile, South America. The island is located in the Pacific Ocean about 3,700 km to the west of Chile and is well known for its giant Moai statues.
It is believed that people started living on Easter Island in about 800 A.D. It was an island covered in tropical rainforests with six species of land birds and 37 species of seabirds.
However, the people on the island kept cutting down trees from the tropical rainforests to use as fuel for fires, to make canoes, or to move the stones used for the Moai statues.
As a result, around 1600, most of the trees in the tropical rainforests had been cut down. Because of this, all the land birds inhabiting the forests left and only one among the 32 species of seabirds remained.
Easter Island's growing population had used trees faster than the forests could replace them. This caused soil erosion; and after a certain point, trees simply could no longer grow there.
Because trees could not grow, there was no wood to make canoes for fishing. Without the ability to fish, food supplies dwindled and island residents began competing for resources. Because of this, the island's population dropped from a peak of 10,000 to just 2,000. The population continued decreasing until there was no one to pass down the culture. They destroyed not only the nature of the island, but also the society of the humans that had once thrived there.
Easter Island today is completely different from a thousand years ago, when it had abundant nature and birds filled the sky. There are now no trees taller than 3 meters, and most of the island has become a desert.

Case 2. Lake Erie in the United States

Lake Erie is one of the five Great Lakes (freshwater) situated on the border between Canada and the United States. Lake Erie is surrounded by Ohio, Pennsylvania, and New York, and these states have prospered because of the benefits from the lake.
Lake Erie contributed to the development of a freshwater fishery and related commerce. A wide network of canals connecting to Lake Erie allowed distribution to surrounding areas and became the basis for their industries and cities. There is a close relationship between Lake Erie and the development of the lakeside areas.
However, between the 1950s and 1960s, pollution became a serious problem. Wastewater discharged into Lake Erie from factories, homes, and farms led to eutrophication of the lake water, which caused pollution.
Eutrophication occurs when water becomes overly enriched with nutrients. This allows an excessive amount of phytoplankton such as algae to grow. A large amount of wastewater containing phosphorus was discharged into Lake Erie, causing eutrophication and generating a large amount of blue-green and other kinds of algae.
The algae covering the lake blocked the sunlight, which prevented photosynthesis from occurring in plants living in the water. This deteriorated the lake's ability to filter out impurities. As a result, the lake's environment was disrupted. As the amount of algae increased, the oxygen levels in the water decreased. This resulted in the death of fish, shellfish, and plants. Lake Erie came to be known as the Dead Sea of North America.
In response, the American and Canadian Governments signed the Great Lake Water Quality Agreement in 1972 to initiate measures to improve the water quality of Lake Erie and the other Great Lakes. It is said that the approaches succeeded in reducing eutrophication by a considerable degree. However, a large amount of algae was produced again in 2014. The water quality of Lake Erie remains an important issue.

Summary

Case 1 is an example of tropical rainforests on Easter Island that were destroyed by excessive deforestation. The content of nitrogen in the soil, which helps to fertilize it, is thought to be related to the threshold. Soil erosion caused by deforestation significantly reduced the amount of nitrogen in soil, thus damaging the land's reproduction capacity. This case shows how the destruction of nature destroys society, which is an important lesson.

Case 2 shows the growth of an excessive amount of phytoplankton and the destruction of the ecosystem in Lake Erie due to eutrophication caused by the discharge of wastewater from homes and farms containing phosphorus into the lake. The amount of phosphorus exceeded the self-recovery capability of the lake (threshold) and resulted in the loss of resilience. Loss of resilience changed it into a polluted lake, which prevented local residents from reaping the benefits of Lake Erie.
As in Case 1 above, Case 2 proved that the natural ecosystem will not be able to return to its original state after crossing the threshold of resilience. This provides many lessons about sustainability of the social-ecological systems, the integration of ecosystems and human society.