researchers use peat beds to understand climate change

Along Silver Creek, a 10-kilometre creek bed in the southwest corner of the Yukon, Derek Turner searches for evidence of previous glaciations. While most studies agree there have been at least three different edges or extents of glacial coverage of the Yukon, there are theories that the glacial coverage was not all that neat and tidy

Along Silver Creek, a 10-kilometre creek bed in the southwest corner of the Yukon, Derek Turner searches for evidence of previous glaciations.

While most studies agree there have been at least three different edges or extents of glacial coverage of the Yukon, there are theories that the glacial coverage was not all that neat and tidy. Some boundaries mask multiple glaciations, some of which are smaller and covered parts of the Yukon at different times.

Part of Turner’s work, as a PhD student at Simon Fraser University, is to confirm when glaciations happened.

Turner does his research within reach of the Kluane Lake Research Station, run by the Arctic Institute of North America.

He uses the station as a base camp from which to hike out to different spots on the creek. Riley Gibson, his assistant, and a local geologist from Whitehorse, hikes out with him. They are gone all day, sometimes days at a time, climbing mountains and cliffs.

Turner and Gibson look for preserved sediments in the strata of old sediment on the edge of Silver Creek.

Beringia – that large area of unglaciated northern Yukon, and parts of Siberia – helped preserve its own regional plant, animal and even insect history in permafrost, freezing and preserving peat beds from thousands of years ago.

“Those peat beds can tell us a lot,” says Turner. “They preserve plant life, ants, beetles, everything you’d find on a forest floor – a forest floor from 130,000 years ago.”

Knowing what was around during that time period – before and after a glaciation – helps researchers understand the warming cycles in between.

“If we’re going to understand climate change – especially for this region – we can study those peat beds to understand how fast or how slow it warmed up; we can determine a lot from the beds,” says Turner. “For instance, we can determine that 130,000 years ago this area had a boreal forest. And we can see how these warm periods changed coming into and out of glaciations across different regions. Peat beds are full of information.”

It’s important to figure out which parts of the Yukon glaciers covered, and when. It’s also important to know how a region was affected by rapid temperature change.

“You want to know what happens in different regions, what weather patterns happened, if it warmed up slowly or quickly, and how the environment reacted to these changes,” says Turner. “How warm were the warm periods?”

Dating the glaciers takes more than radiocarbon dating, which is only accurate from today back to 30,000 to 50,000 years ago. Turner studies the different layers of tephra in the rock strata. Tephra is volcanic ash – this particular tephra is from Alaskan volcanoes – and you can date the sediment using the tephra.

“You extract little shards of glass and you analyze their chemistry and then compare those with a database of dated samples. So, since you know that certain dated tephras are 130,000 years old – if the chemistry of your sample matches this sample really well, then you can say that your sample is 130,000 years old and therefore the sediments and the peat that is with that tephra is 130,000 years old.”

Turner will later analyze and date the tephra found in the peat beds at the University of Alberta-Edmonton this fall.

It’s important to time-stamp the tephra, and by relation, the peat beds. In this way, Turner is trying to time-map Silver Creek and White River.

“I think it’ll be a pretty good contribution to be able to say – pick any point in the last 200,000 years and I will be able to tell you what climate was like and what was going on at Silver Creek and White River.”

But Turner realizes he’s far from that goal. And that while he might eventually be able to tell someone what happened at Silver Creek, he’d be guessing if he tried to tell you what happened several kilometres away from the creek.

“You need a higher resolution of samples around to get a really good feel to what the climate was like and that’s what these tephra beds allow you to do – to correlate with different areas where other people have done research.”

There’s a handful of researchers doing what Turner is doing. “We’re still sort of in the dark ages in doing this,” he says. “There’s still a lot of work to be done. And there’s so much unexplored area that we’re getting only pinpricks in a dark sky.”

Eventually he’ll be able to look at other research done around Yukon and Alaska, and correlate, getting a more regional feel of – not only what Silver Creek looked like – but what Beringia looked like, what the Yukon looked like at this time.

In that way, they can make much more broad implications on what the climate was like 130,000 years ago. And, eventually, be able to give us a better picture of what the future might hold for the Yukon as it is affected by climate change.

“This is a lifetime’s work. Many people’s lifetimes of work,” he says. Research already done earlier in the 60s and 70s on the White River contributes to Turner’s own on Silver Creek.

“It’s one of the joys of being a Quaternary geologist – your work is studying the last 2.6 million years. You don’t study the whole thing by yourself. ”

As well, the sections along Silver Creek were first discovered by George Denton, a PhD student at Harvard University, and his hiking partner, Sir Edmund Hillary.

“They were able to date some of the beds using radiocarbon dating—but since that has a certain maximum limit – they were able to only discuss the geology older than that in broad terms. Now we can actually go in – and we have the technology to say, ‘Yes, this is what it is, and this is when it was.’ So we have much more data at our fingertips now than they would have had forty years ago.”

Turner uses tools Denton and Hillary didn’t have. “I use Google Earth sometimes to look at the stratigraphy in the cliffs around the creek. The resolution is so good you can actually make out the different beds.”

He uses Google Earth to get an idea of where to hike next, so he can more closely examine those layers. On such a long creek, inaccessible by boat and often by vehicle, it’s a handy way of finding out where to look deeper to uncover more evidence of glacial events in the area. But Google Earth doesn’t make everything easy. “We still have to pull ourselves up the side of the cliff using willow branches,” says Turner.

For more information about research at Kluane Lake Research Station, contact Derek Turner at dgturner@sfu.ca, or Ruth Klinkhammer, Arctic Institute Director of Communications, at r.klinkhammer@ucalgary.ca

This column is co-ordinated by the Northern Research Institute at Yukon College with financial support from Environment Yukon and Yukon College. The articles are archived at www.taiga.net/yourYukon.

Get local stories you won't find anywhere else right to your inbox.
Sign up here

Just Posted

Crystal Schick/Yukon News
Calvin Delwisch poses for a photo inside his DIY sauna at Marsh Lake on Feb. 18.
Yukoners turning up the heat with unique DIY sauna builds

Do-it-yourselfers say a sauna built with salvaged materials is a great winter project

d
Wyatt’s World

Wyatt’s World for March 5, 2021.

g
Yukonomist: School competition ramps up in the Yukon

It’s common to see an upstart automaker trying to grab share from… Continue reading

The Yukon government responded to a petition calling the SCAN Act “draconian” on Feb. 19. (Yukon News file)
Yukon government accuses SCAN petitioner of mischaracterizing her eviction

A response to the Jan. 7 petition was filed to court on Feb. 19

City councillor Samson Hartland in Whitehorse on Dec. 3, 2018. Hartland has announced his plans to run for mayor in the Oct. 21 municipal election. (Crystal Schick/Yukon News file)
Councillor sets sights on mayor’s chair

Hartland declares election plans

Chief Medical Officer of Health Dr. Brendan Hanley receives his first dose of the COVID-19 vaccine from Public Health Nurse Angie Bartelen at the Yukon Convention Centre Clinic in Whitehorse on March 3. (Crystal Schick/Yukon News)
State of emergency extended for another 90 days

“Now we’re in a situation where we see the finish line.”

The Yukon government says it is working towards finding a solution for Dawson area miners who may be impacted by City of Dawson plans and regulations. (Joel Krahn/Yukon News file)
Miner expresses frustration over town plan

Designation of claims changed to future planning

Team Yukon athletes wave flags at the 2012 Arctic Winter Games opening ceremony in Whitehorse. The 2022 event in Wood Buffalo, Alta., has been postponed indefinitely. (Justin Kennedy/Yukon News file)
2022 Arctic Winter Games postponed indefinitely

Wood Buffalo, Alta., Host Society committed to rescheduling at a later date

Housing construction continues in the Whistle Bend subdivision in Whitehorse on Oct. 29, 2020. (Crystal Schick/Yukon News file)
Yukon Bureau of Statistics reports rising rents for Yukoners, falling revenues for businesses

The bureau has published several reports on the rental market and businesses affected by COVID-19

Council of Yukon First Nations grand chief Peter Johnston at the Yukon Forum in Whitehorse on Feb. 14, 2019. Johnston and Highways and Public Works Minister Richard Mostyn announced changes to the implementation of the Yukon First Nations Procurement Policy on March 3. (Crystal Schick/Yukon News file)
Third phase added to procurement policy implementation

Additional time added to prep for two provisions

Crews work to clear the South Klondike Highway after an avalanche earlier this week. (Submitted)
South Klondike Highway remains closed due to avalanches

Yukon Avalanche Association recommending backcountry recreators remain vigilant

RCMP Online Crime Reporting website in Whitehorse on March 5. (Haley Ritchie/Yukon News)
Whitehorse RCMP launch online crime reporting

Both a website and Whitehorse RCMP app are now available

A man walks passed the polling place sign at city hall in Whitehorse on Oct. 18, 2018. The City of Whitehorse is preparing for a pandemic-era election this October with a number of measures proposed to address COVID-19 restrictions. (Crystal Schick/Yukon News file)
City gets set for Oct. 21 municipal election

Elections procedures bylaw comes forward

Most Read