Palm trees in Vancouver? Florida's climate in Burnaby? Plant fossils suggest region once had a warmer climate

There was a time when Burnaby Mountain, and the areas around it along B.C.'s south coast, was a warmer, less mountainous region where palm trees grew, according to new research that identified plant fossils unearthed at the site more than 50 years ago. 

When Simon Fraser University was being built in the late 1960s, paleobotanist Rolf Mathewes was an undergraduate, and he helped gather dozens of plant fossils at a deposit exposed by the construction site. The fossils date back to around 40 million years ago.

SFU then locked the specimens in cabinets, where they remained largely untouched for decades.

Now a professor at the university and at the twilight of his career, Mathewes set out to revisit the plant fossils he helped collect.

"I thought, before I retire, I should really publish something on these fossils. They've never been published and never really been studied," said Mathewes. 

Mathewes and his research team verified the collection contained a mix of subtropical and temperate forest elements, giving clues about Burnaby Mountain's climate in the distant past. 

The findings were published in the International Journal of Plant Sciences this month, looking into the plant fossils that date back to the late Eocene period. The Eocene lasted from 55.8 to 33.9 million years ago and is known for its warmer climate.

Palm trees once in B.C.?

Mathewes says a significant fossil in the collection was a palm leaf fragment. Palm trees can still be planted in B.C., but they can no longer thrive in the region.

"If you wanted to match what kind of climate they're telling us was here, the best match is somewhere around Cape Fear on the East Coast of the United States," said Mathewes.

Mathewes says a global cooling period that followed the Eocene era allowed for the palms in the area to be slowly replaced by temperate trees like elms and sweetgum.

"The palms can tolerate it here, but it's not warm and tolerant enough to make it into the forest."

The team also identified a hydrangea flower and a flower of an extinct plant related to the basswood, which is native to Eastern North America. 

"Some of the things that turned up were amazingly surprising ... That includes some flowers and seeds of plants that don't grow here and are only found in either Asia or in eastern North America."

Mathewes also notes the Burnaby Mountain region resembled a floodplain during the Eocene.

"It was a sea-level plain near the ocean with rivers and ponds and marshes on it, and that's where the fossils were produced," he said.

'A glimpse of ... what things might look like'

Kendra Chritz, an earth sciences professor at the University of British Columbia who was not involved in the study, says finding the palm in the fossil locality gives further evidence of Metro Vancouver's climate being warm and humid around that period.

"If you think about places where palms grow naturally now like California, Florida or Mexico, imagine something like that but in British Columbia. It's very warm, very wet and diverse," Chritz said.

Chritz says it's important to study periods like the Eocene to help understand today's changing climate. She says the Eocene period had high levels of carbon dioxide, which could inform today's increasing levels. 

"This kind of gives us a glimpse of maybe what things might look like, but we also have to remember that this is well before we existed."

Chritz says human activities put a different context to a warming climate, when animals and plants cannot move around and adapt as easily as they did in the distant past. 

Mathewes says he's happy to have revisited the fossils he helped collect decades ago. The study is dedicated to his late mentor who oversaw the excavation, Robert C. Brooke.

"I'm glad I managed to finally finish analyzing the story with the help of my colleagues," Mathewes said.

"I should have done it years ago, but I was tied up."