According to a study of ancient rainforests, trees may be hardier than previously thought. Carlos Jaramillo, a scientist at the Smithsonian Tropical Research Institute (STRI), examined pollen from ancient plants trapped in rocks in Colombia and Venezuela. “There are many climactic models today suggesting that … if the temperature increases in the tropics by a couple of degrees, most of the forest is going to be extinct,” he said. “What we found was the opposite to what we were expecting: we didn’t find any extinction event [in plants] associated with the increase in temperature, we didn’t find that the precipitation decreased.”

In a study published today in Science, Jaramillo and his team studied pollen grains and other biological indicators of plant life embedded in rocks formed around 56m years ago, during an abrupt period of warming called the Paleocene-Eocene Thermal Maximum. CO2 levels had doubled in 10,000 years and the world was warmer by 3C-5C for 200,000 years.

Contrary to expectations, he found that forests bloomed with diversity. New species of plants, including those from the passionflower and chocolate families, evolved quicker as others became extinct. The study also shows moisture levels did not decrease significantly during the warm period. “It was totally unexpected,” Jaramillo said of the findings.