"Global warming in recent years has accelerated the thawing of the glaciers near the lake in the springtime, which is the major reason for the lake's expansion," said Fu Yang, director of the telemetric monitoring center under the provincial meteorological institute. "It's also true that we have had more summer rainfall over the past few years."

    Qinghai Lake is China's largest inland salt lake, which was listed among the nation's natural heritage sites this year because of its scenic landscape and abundant resources.

    Located in the southern part of the Qaidam Basin, it has expanded from 4,254 sq km in July 2004 to its current size of 4,285 sq km. Less evaporation in recent years has also contributed to the expansion, Fu said.

    Due to declining rainfall and desertification partly caused by overgrazing, Qinghai Lake shrank in the 1990s. Last July's increase in size was the first in 15 years, said Fu.

    This year the expansion has continued -- and at a faster rate.

    "We found that the lake increased 10.99 sq km between July and September this year," said Fu, attributing the accelerated expansion to unusually rich rainfall over the summer.

    Average precipitation in the lake area in August and September this year doubled in the same period of last year.