Bolivia is especially vulnerable to the negative consequences of climate change. Twenty percent of the world's tropical glaciers are located within the country, and are more sensitive to change in temperature due to the tropical climate they are located in. Temperatures in the Andes increased by 0.1 °C per decade from 1939 to 1998, and more recently the rate of increase has tripled (to 0.33 °C per decade from 1980 to 2005), causing glaciers to recede at an accelerated pace and create unforeseen water shortages in Andean agricultural towns. Farmers have taken to temporary city jobs when there is poor yield for their crops, while others have started permanently leaving the agricultural sector and are migrating to nearby towns for other forms of work; some view these migrants as the first generation of climate refugees. Cities that are neighbouring agricultural land, like El Alto, face the challenge of providing services to the influx of new migrants; because there is no alternative water source, the city's water source is now being constricted.