What Plant Fossils Reveal About Climate Change | Smithsonian Voices

Fossil plants reveal information about the temperature and precipitation of past climates. Scientists are using what they learn from fossil plants to inform their research on modern climate change (USNM PAL 606436, Smithsonian)

In a world obsessed with human ingenuity, plants are perhaps the most underrated innovators. Their adaptability stems from necessity. Plants cannot take root elsewhere in the face of an inhospitable environment.

“Plants are masters of taking what’s available and using it to their advantage,” said Rich Barclay, research geologist in the department of paleobiology at the Smithsonian’s National Museum of Natural History.

In each habitat, these clever inventors have developed different features to help them survive. For millions of years, plants have left evidence of these characteristics in the fossil record. Paleobiologists can study this record to learn more about plants, their surrounding environments, and how those environments have changed over time.

Using part of the museum’s collection of 7.2 million plant fossils, Barclay and Scott Wing, a research geologist and curator of paleobotany at the museum, are uncovering clues to past periods of climate change. What they discover will help scientists grasp the full extent of climate change today.

“If we can interpret plant changes over time, we can get a sense of what past climates were like and how they changed,” Barclay said.

Fossil leaves as climate keys

When studying the museum’s collection of plant fossils for information about climate, Wing and Barclay begin with the leaves of plants.

Fossil palm leaf in silver rock on black background

Many types of warm climate plants, including palms, used to grow in places too cold for them now. Scientists have discovered this sixty-million-year-old fossil palm leaf (Sabalites sp.) in Petersburg Borough, Alaska (Lucia RM Martino, Smithsonian)

Typically, plants in warmer climates have larger leaves with smoother edges, while plants in colder climates have smaller leaves with more serrated edges.

“If I have an assortment of leaf fossils from one location, I can get an idea of ​​the temperature from the proportion of smooth-edged species,” Wing said.

By comparing fossil plants with their modern relatives, Wing and Barclay can deduce what type of climate the plants lived in. For example, today’s palms are exclusively tropical or subtropical plants. Thus, the duo can deduce that a fossilized palm tree probably grew in a warm climate.

“It’s like finding a fossilized polar bear. I don’t know exactly what the weather was like at the time, but the fact that there was a polar bear is a pretty strong indication that it was cold,” Wing said.

Footprints of ancient ecosystems

About 56 million years ago, at a time called the Paleocene Eocene Thermal Maximum (PETM), Earth’s average temperature rose four to eight degrees Celsius in less than 10,000 years. The cause was geological processes releasing trillions of tons of carbon dioxide into the atmosphere. The dramatic change in global climate has led to a massive upheaval in ecosystems around the world.

“It’s the best analogue for climate change that we know of today,” Barclay said.

Fossil plants and their leaves from the PETM show that ecosystems shifted massively due to the rapid increase in global temperature. But the global warming during the PETM did not come from man. So scientists are now working on ways to extrapolate information from that period and apply it to the even faster and more drastic events of today.

Old factories, new ideas

Person with fossils arranged in museum storage

Paleobotanist Scott Wing studies the National Museum of Natural History’s paleontology collection for evidence of past environmental changes that can inform conversations about climate change today. (Chip Clark, Smithsonian)

The National Museum of Natural History’s fossil plant collection helps paleobiologists learn more about past climate to better understand current and future climate change.

“We use the fossils to tell us what the climate was like a long time ago. Then the climatologists run computer simulations of the past climate. We can then compare the results of the simulation with the reconstructed climate to see if they agree” , said Wing.

If a modern climate model can successfully predict extreme past events like the PETM, then it is more likely to give accurate predictions of how the planet will respond to climate change today.

“Paleobotanists are citizens of the world,” Barclay said. “We are worried about what is happening.”

The Evolving Climate series continues May 6 when we show you how researchers in the museum’s botany department are using the US National Herbarium’s 5 million plant specimens to study how plants have adapted to changing climates over time. time.

Changing climate: The Smithsonian is much more than its world-renowned exhibits and artifacts. It is an organization dedicated to understanding how the past informs the present and the future. Once a week, we’ll show you how the National Museum of Natural History’s seven scientific research departments are taking lessons from past climate change and applying them to the 21st century and beyond.

Related stories:
Bison mummies help scientists ruminate on ancient climate
What a 1,000-year-old seal skull can tell about climate change
Get to know the scientist reconstructing past ocean temperatures
Here’s how scientists reconstruct Earth’s past climates
Can you help us clear the fossil air?