Why are lakes in China disappearing?
About half of the lakes in a northern region of China have vanished over the last few decades, scientists report. And with climate change, even more lakes could dry out, threatening endangered species such as red-crowned cranes.
The study isn’t the first report of shrinking lakes. In Africa, Lake Chad shriveled up to about 5 percent of its former size between 1963 and 2001. In Turkey, Lake Aksehir — which covered nearly 350 square kilometers in 1975 — disappeared a few years ago. Researchers blame drier climates for the change, as well as sloppy management of water for irrigation.
The study authors examined lakes in a 1.2-million-square-kilometer region of China, mainly on the Inner Mongolian Plateau. Waterfowl depend on wetlands in this area; scientists have catalogued 119 bird species, including six crane species. The region is also home to about 30 million people, many of whom tend crops or raise livestock.
The researchers gathered temperature and precipitation data and studied satellite images of 241 lakes taken from the 1970s to late 2000s. Then they calculated the change in lake area and looked for links to climate or human activities.
From 1975 to 2009, 121 of the lakes became “fully desiccated,” the team writes in Environmental Science & Technology. The lakes appeared to shrink mainly when temperatures rose and precipitation dropped. Conditions have become drier at all 241 sites, the researchers say. Since some of the disappearing lakes were in an area with extensive farming, people’s water use might have contributed to the problem.
The team also discovered that salty marshes have expanded, and freshwater marshes have dwindled. The shift could hurt cranes that rely on freshwater habitat. And saltier conditions could end up damaging fisheries as well. — Roberta Kwok | 22 October 2013
Source: Liu, H. et al. 2013. Disappearing lakes in semiarid northern China: Drivers and environmental impact. Environmental Science & Technology doi: 10.1021/es305298q.
Image © liu jian | Shutterstock
Could higher carbon levels actually benefit some crops?April 29th, 2016