UW News has published a story about how reconstructing ancient climates can provide insight into the impacts of anthropogenic climate change. A 15-year study of a site in Bolivia by a joint U.S.-Bolivia team has provided a comprehensive view of an ancient ecosystem when Earth was much warmer than it is today. The researchers’ findings were published online Nov. 1 by the journal Palaeogeography, Palaeoclimatology, Palaeoecology. The team’s results also indicate that the Andes could be much younger than previously thought, upending assumptions about when South America became a global biodiversity hotspot.

Lead author on the paper is Dr. Caroline Strömberg, a UW professor of biology, who studied fossilized phytoliths – microscopic pieces of silica from plant cells – found at the site, which was deposited approximately 13 million years ago. The team was co-led by scientists at Case Western Reserve University and the Universidad Autonóma Tomás Frías in Bolivia.

As Earth faces unprecedented climate change, a look into the planet’s deep past may provide vital insights into what may lie ahead. But knowledge of the natural world millions of years ago is fragmented.

A 15-year study of a site in Bolivia by a joint U.S.-Bolivia team has provided a comprehensive view of an ancient ecosystem when Earth was much warmer than it is today. The researchers’ findings were published online Nov. 1 by the journal Palaeogeography, Palaeoclimatology, Palaeoecology.

Located in the Andes Mountains of southern Bolivia, the site, known as the Quebrada Honda Basin — or QHB — was deposited 13 million years ago during the Miocene Epoch, when Earth’s climate was rebounding from a prior period of warming. Globally, temperatures were 3-4 degrees Celsius warmer than today, and mammal biodiversity was increasing markedly.

Today, the site is 11,500 feet above sea level. Back in the Miocene, the site was lower, but exactly how much was a matter of debate. Previous studies using geochemical methods estimated that the Miocene QHB was relatively high, close to 10,000 feet. But the team’s new findings, based on careful analysis of plant and animal fossils and other features at the site, favor an alternative theory: That the Miocene QHB was at a much lower elevation, likely less than 3,000 feet.

“Our new data indicates that this area was once covered by mosaic vegetation with a mix of trees, including palms, bamboos and other grasses,” said lead author Caroline Strömberg, a University of Washington professor of biology. “Although this vegetation lacks a good comparison in today’s South America, it was likely most similar to modern neotropical dry forest or wooded savanna growing at low elevation.”

A lower-elevation Miocene QHB site has potentially global consequences.

“When put together with previous work at QHB, our study — including looking at fossil soils, turtles and other ectothermic vertebrates, and mammal ecologies — suggests that the Central Andes still had not undergone substantial uplift by 12 million years ago,” said Strömberg. “This is important because it helps us understand when this major mountain chain formed. The rise of the Andes is thought to have contributed to making tropical South America the most biodiverse area on Earth.”

Read the full article in UW News.