SFU paleoecologist discusses the past, present and future of Earth’s climate

Dr. Rolf Mathewes’ seminar discusses evidence of environmental changes

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This is a photo of a fossilized animal in the ground. Its bones are lying in perfect formation. The animal appears to be prehistoric.
PHOTO: David Clode / Unsplash

By: Olivia Sherman

Dr. Rolf Mathewes is a professor of paleoecology, the study of ancient ecosystems, and is SFU’s longest serving faculty member in the department of biology. He has been a member of SFU since his undergraduate studies began in 1967. Mathewes has also served as a forensic botanist, interpreting plant remains that are evidence in homicide cases. One of his recent discoveries from the Eocene Epoch, spanning 5633 million years ago, is from Lhuḵw’lhuḵw’áyten (Burnaby Mountain). His data proves that during this time period, Lhuḵw’lhuḵw’áyten was a tropical environment. 

The name Eocene comes from the Greek word eos, meaning “dawn.” Eos was the godly personification of the dawn in the Greaco-Roman religion. This name is in reference to the appearence of many of the modern life forms we know today such as mammals. Our current epoch, Holocene, is named after two Greek words: ὄλος, holos, and καινή, kai-ne. These mean “whole” and “recent.”

His seminar on October 30, “Time Travels of a Paleoecologist,” explained fire history and climate change from a paleoecological lens. Mathewes covered the Eocene Epoch to the Holocene Epoch, which spans about 10,000 years to the present day. In the late 1960s, Mathewes and his supervisor, Dr. Robert Brooke, discovered fossil samples where many campus buildings are today. These Eocene fossils include samples such as leaves, pollen, and other flora. “But neither of us was a paleobotanist at the time, so they all got stored in cabinets. Nothing was done with them until I started work on them.” 

The findings from these particular samples show they are fossils of plants no longer growing here because they require more tropical environments, like the craigia oregonensis, only found in temperate areas of modern-day China. Mathewes said the best comparison for what Lhuḵw’lhuḵw’áyten would look like in the Eocene Epoch would be Wilmington, North Carolina, due to both environments’ abundance of tropical plants, like gum trees and palms

Mathewes then moved the discussion to the Pleistocene Epoch, which lasted from 2.6 million years ago to about 12,000 years ago. This period saw a span of ice ages. Scientists struck more than gold when they excavated Klondike, in the Yukon Territory, where they found fossilized organisms like mammoths, steppe-bison, and short-faced bears. Other animals included grazing animals, such as horses and yaks. This discovery led scientists to consider what these animals were consuming because the territory was previously thought to be a desolate tundra. Mathewes explained this has been dubbed the “productivity paradox,” named after the unproductive, harsh, and unnurturing tundra. The fossil evidence of these animals is paradoxical to this idea. Studying vegetation, Mathewes argued, is the key to understanding how these ancient animals both lived and died. 

Mathewes used the fossilized body of a ground squirrel in its nest as an example of how animals related to their environments. The nest, preserved underground, is embedded with plant material the squirrel collected, such as conifer needles, fruits, and seeds. Mathewes and his research team noted one plant in particular, Artemisia frigida, or prairie sagewort, which isn’t known to grow in the north where the squirrel body is preserved. Therefore, the Klondike must have seen prairie-like conditions at some point in time. Once the environment changed from prairie to the tundra it is today, the extinctions began, Mathewes explained. The changing climate, loss of grasslands, and overhunting endangered some of the large, grazing animal populations like horses and bison, who relied on these environments. 

Mathewes then jumped forward to the Anthropocene, or, the age defined by human activity and environmental impact. The past few years have seen increasing wildfires across BC, a worldwide trend that is being exacerbated annually. 

Using layers of accumulated sediment in lake beds and bogs, Mathewes said we can determine the state of the climate at the time sediment from pollen and other materials was deposited. Mathewes dubbed pollen as “nature’s fingerprints,” as experts can read the history of the environment in the sediment just through this material, and predict future trends. Using this data, Mathewes predicted many more alder trees would grow in BC’s coastal rainforest. This is a species of tree that always grows after fires. 

“We’re at a global tipping point, where lots of systems are on the edge of long-term stability. ‘Stability’ is a big question mark these days,” Mathewes noted. “Paleoecology can tell us something about how we got to the present, understand how we got here, and is maybe a heads-up on the Anthropocene future.

“This is my future prediction: fire frequency and severity is going to increase from where it is today. Drought frequency and severity is going to increase from where it is today. Storm frequency and severity is going to increase from where it is today. And the political and societal responses to food shortages and natural disasters are not positive.” 

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