Catastrophic drought is on the near-term horizon for the capital city of Bolivia, according to new research into the historical ecology of the Andes.
If temperatures rise more than 1.5 to 2 degrees Celsius (3 to 5 degrees Fahrenheit) above those of modern times, parts of Peru and Bolivia will become a desert-like setting.
The change would be disastrous for the water supply and agricultural capacity of the two million inhabitants of La Paz, Bolivia's capital city, scientists say.
The results, derived from research funded by the National Science Foundation (NSF) and conducted by scientists affiliated with the Florida Institute of Technology (FIT), appear in the November issue of the journal Global Change Biology.
Climatologist Mark Bush of FIT led a research team investigating a 370,000-year record of climate and vegetation change in Andean ecosystems.
The scientists used fossilized pollen trapped in the sediments of Lake Titicaca, which sits on the border of Peru and Bolivia.
They found that during two of the last three interglacial periods, which occurred between 130,000-115,0000 years ago and 330,000-320,000 years ago, Lake Titicaca shrank by as much as 85 percent.
Adjacent shrubby grasslands were replaced by desert.
In each case, a steady warming occurred that caused trees to migrate upslope, just as they are doing today.
However, as the climate kept warming, the system suddenly flipped from woodland to desert.
"The evidence is clear that there was a sudden change to a much drier state," said Bush.
Scientist Sherilyn Fritz at the University of Nebraska-Lincoln showed that during these warm episodes the algae living in Lake Titicaca shifted from freshwater species to ones tolerant of salty water. Paul Baker of Duke University identified peaks of carbonate deposition.
Both point to a sudden shallowing of the lake due to evaporative loss.
An environmental reconstruction demonstrates that with moderate warming, forests moved upslope. But as that warming continued, a climate tipping point was reached.
The system was thrown into a new, drier state that halted forest expansion.
The tipping point is caused by increased evaporative loss from Lake Titicaca.
As the lake contracts, the local climate effects attributable to a large lake--doubling of rainfall, among the most important--would be lost, says Bush.
Such tipping points have been postulated by other studies, but this work allowed the researchers to state when the system will change.
Based on the growth limits of Andean forests, they defined a tipping point that was exceeded within a 1.5 to 2 degrees Celsius warming above modern conditions.
Given a rate of warming in the Peruvian Andes of about 0.3-0.5 degrees Celsius per decade, the tipping point ahead would be reached between 2040 and 2050.
"The implications would be profound for some two million people," says Paul Filmer, program director in NSF's Division of Earth Sciences. Severe drought, and a loss of stored water in lakes in the region, would reduce yields from important agricultural regions and threaten drinking water supplies.
The research suggests that limiting wildfires would help delay the worst effects of the drought.
Cheryl Dybas | EurekAlert!
Air pollution leads to cardiovascular diseases
21.08.2018 | Universitätsmedizin der Johannes Gutenberg-Universität Mainz
Waste in the water – New purification techniques for healthier aquatic ecosystems
24.07.2018 | Eberhard Karls Universität Tübingen
There are currently great hopes for solid-state batteries. They contain no liquid parts that could leak or catch fire. For this reason, they do not require cooling and are considered to be much safer, more reliable, and longer lasting than traditional lithium-ion batteries. Jülich scientists have now introduced a new concept that allows currents up to ten times greater during charging and discharging than previously described in the literature. The improvement was achieved by a “clever” choice of materials with a focus on consistently good compatibility. All components were made from phosphate compounds, which are well matched both chemically and mechanically.
The low current is considered one of the biggest hurdles in the development of solid-state batteries. It is the reason why the batteries take a relatively long...
New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference
Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...
Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...
Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.
When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...
Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.
Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....
17.08.2018 | Event News
08.08.2018 | Event News
27.07.2018 | Event News
21.08.2018 | Ecology, The Environment and Conservation
21.08.2018 | Life Sciences
21.08.2018 | Power and Electrical Engineering