PROVIDENCE, R.I., July 21 (UPI) -- Africa's Lake Tanganyika, the second-oldest and second-deepest lake on Earth, is warmer now than it has been in 1,500 years, scientists say.
Experiencing unprecedented warming during the last century, the lake's surface waters are the warmest on record, LiveScience.com reported Wednesday.
The warmer waters are linked to a decrease in the lake's productivity, affecting fish stocks depended upon by millions of people in the region, researchers say.
Rift lakes like Tanganyika are created when two of Earth's continental plates move apart, expand and eventually become ocean basins over millions of years.
Lake Tanganyika is 13 million years old and nearly a mile deep. The world's deepest lake is Lake Baikal in Siberia, at 5,387 feet deep.
A high average temperature in the lake of 78.8 degrees Fahrenheit, measured in 2003, is the warmest the lake has been in a millennium and a half, LiveScience reported.
The high temperatures worry scientists looking at the estimated 10 million people who live near the lake and depend on fishing for their diet and livelihood.
"Our data show a consistent relationship between lake surface temperature and productivity (such as fish stocks)," said geologist Jessica Tierney of Brown University. "As the lake gets warmer we expect productivity to decline, and we expect that it will affect the fishing industry."
Lake Tanganyika is bordered by Burundi, the Democratic Republic of Congo, Tanzania and Zambia, four of the poorest countries in the world according to the U.N. Human Development Index.