Climate change could bring sudden drought to La Paz

As the world warms, scientists expect some ecosystems to gradually migrate up slopes, essentially chasing environmental conditions they need to thrive.

But according to recent research on the historical ecology of the Andes conducted in part by a Westfield State University assistant professor, those steady changes can reach a tipping point in some cases that flips local ecosystems on their head.

The scientists examined fossilized pollen in Lake Titicaca, the world’s highest elevation great lake on the border of Peru and Bolivia, which allowed them to look 370,000 years back in time. They found that in two periods of past warming, the lake shrank by as much as 85 percent, and switched the grassland ecosystem into desert.

Based on their work, the group then projected if temperatures rise between three to five degrees Fahrenheit, parts of high elevation area Bolivia and Peru will become desert-like as early as 2040. That change could be disastrous for the water supply and farming of Bolivia’s capital city, La Paz.

“We essentially did an environmental reconstruction," said Jennifer Hanselman, the Westfield State professor formerly affiliated with the Florida Institute of Technology. "We looked at the climate and vegetation evidence over a 370,000-year record and were able to determine when the area around La Paz, Bolivia will be impacted by drought, which we estimate will be between 2040 and 2050,” .

Scientists have long assumed such tipping points would take place but the study allowed the researchers to do something new: Project the future. The research was funded by the National Science Foundation and appeared in the November issue of Global Change Biology.

"The implications would be profound for some two million people," says Paul Filmer, program director in NSF's Division of Earth Sciences.