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How soil and squirrels offer cues on Alaska climate change

November 24, 2014 at 6:25 PM EDT
On the Alaskan tundra, researchers are tracking the march of global warming. Science correspondent Miles O’Brien explores how soil composition and the sleep schedules of squirrels might offer data on the ways warmer temperatures are affecting ecosystems.
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GWEN IFILL: Now the second of two field reports from Alaska on the impact of climate change and warmer temperatures.

Science correspondent Miles O’Brien reports from the 49th state on how those changes are affecting greenhouse gas levels and the consequences for the local ecosystem.

MILES O’BRIEN: To get to the root of global warming in the Arctic, scientists need to pull out some serious tools.

WOMAN: On three. Yes.

(LAUGHTER)

MILES O’BRIEN: But that doesn’t mean they have to take themselves too seriously.

Near Alaska’s Toolik Field Station, caught up with a pair of researchers on a backbreaking mission to drill cores in soil frozen hard as concrete.

MEGAN MACHMULLER, Colorado State University: It’s hard work, especially hard to pull up frozen soil.

It’s something that we’re very passionate about because, you know, it’s so critical to understand the functions that are beneath our feet. And so that motivates us, and we have fun while we’re doing it.

WOMAN: You think about here? OK. Here we go.

MILES O’BRIEN: Megan Machmuller is a postdoctoral fellow and Laurel Lynch a grad student at Colorado State University. They’re part of a team trying to understand how and when the huge store of carbon, methane and other greenhouse gases permanently frozen in the Arctic tundra might be released into the atmosphere.

LAUREL LYNCH, Colorado State University: Right now, our current estimates are that the Arctic stores more carbon in this landscape than is currently held in our entire atmosphere.

MILES O’BRIEN: Just mention the word tundra, and you probably think of a barren, lifeless landscape. And looking across the horizon here, you might think, well, that is, in fact, the case. But on closer inspection, this place is just brimming with life.

The plant life is vibrant and diverse, and the soil is rich with chemical compounds and thousands of kinds of organisms.

Soil ecologist Matt Wallenstein is the leader of this team.

MATTHEW WALLENSTEIN, Colorado State University: Since the Ice Age, the plants have been taking carbon out of the atmosphere and storing it in the soil. So this has essentially been depositing carbon from the atmosphere into this vault.

MILES O’BRIEN: And here in the Arctic, the climate is warming twice as fast as the rest of the world. As things heat up, microbes thaw out. They start feeding on the soil, expelling carbon dioxide.

MEGAN MACHMULLER: Now, when it’s colder, activity is limited. The Arctic, of course, as we know is warming at an unprecedented rate. So it’s going to be a very unique situation for this ecosystem. Under warmer conditions, we may see a release of carbon back into the atmosphere.

LAUREL LYNCH: It’s easy to feel that you live a few thousand miles from the Arctic and that you’re safe, but we’re not because, as we’re finding out more and more, our atmosphere is connected, and we are all kind of in this together.

MILES O’BRIEN: To find out how much carbon the microbes might release, the team ships the cores back to their lab in Colorado, where they determine the chemistry and composition of the soil, and they extract DNA from the microbes in order to identify them. The data they gather will be incorporated in computer climate models that aim to predict where we are headed.

Do you have a sense, or is the data just not in yet, that we’re near this kind of a tipping point?

MATTHEW WALLENSTEIN: The data is not in yet. If we do indeed reach those tipping points, the consequences would be really dramatic and there would not be anything we can do about it. So it’s really important that we think about what we can do now, while there’s still time to act.

MILES O’BRIEN: Here on the tundra, another team is focused a little higher on the food change, on an animal whose sleep and hibernation patterns take subtle cues that are related to the climate. They are Arctic ground squirrels.

During our visit in May, the sun never set in this beautiful valley. And you might guess the squirrels would take advantage of all that extra daylight to forage and fatten up for the long, dark, cold winter. But it turns out they don’t. The squirrels stick to a rigid schedule. On sunny days, they are out of their burrows by 9:00, back underground by 7:00, like clockwork.

This begs an important question for physiological ecologist Cory Williams.

CORY WILLIAMS, University of Alaska Anchorage: So, the questions we have are, what is the function of maintaining circadian rhythms in an environment that never becomes dark, and what are the cues these animals use to keep their rhythms entrained in a natural environment, in the absence of a light-dark cycle?

MILES O’BRIEN: Williams is a postdoctoral fellow at the University of Alaska in Anchorage. He and his friends had their hands full at Toolik capturing, gassing, drawing blood, and gathering data from body temperature loggers and light-sensitive collars worn by the squirrels they are studying.

CORY WILLIAMS: And these light collars provide us information on when they’re above ground and when they’re below ground.

MAN: OK, girl.

CORY WILLIAMS: And the body temperature provides us information on the circadian body temperature rhythms that they have.

MILES O’BRIEN: He says the squirrels get cues from subtle fluctuations in the light intensity and the temperature, and he is testing their ability to adjust by time-shifting, essentially giving them jet lag, and then returning them to the valley.

The squirrels also have a very strong circannual clock, which dictates when they start hibernating, like this little guy, and when they wake up in the spring.

CORY WILLIAMS: We want to understand how much plasticity they have in terms of being able to adjust their annual timing based on spring snowfall. And we want to know whether this is going to change over time in response to climate change.

MILES O’BRIEN: Will warmer temperatures cause them to wake sooner? And then could the added precipitation in the form of late-season snowfalls, predicted with climate change, make it hard for them to forage for food?

The questions are hard enough to answer for the squirrels alone, but, of course, they are just one piece in a big, complicated puzzle.

CORY WILLIAMS: I think one of the difficulties with a species like the Arctic ground squirrel is that they’re on the food chain for a large number of animals. So wolves feed on them, foxes feed on them, raptors feed on them. Owls will feed on them.

And so in order to make predictions about what’s going to happen to the species, you have to understand what’s going to happen to all of the predators in the system as well.

MILES O’BRIEN: The system is intricately connected by causes and effects. The Trans-Alaska oil pipeline that passes through here offers a reminder that human beings are more than just observers of the changes. We have done much to dig the hole.

Miles O’Brien, for “PBS NewsHour,” Toolik, Alaska.

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