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UAF researchers share signals of change in Arctic

UAF scientists are studying why parts of the are browning. Photo by Skip Walker
Meghan Murphy

University of Alaska Fairbanks researcher Uma Bhatt said the process of global warming is simple.

“More greenhouse gases in the atmosphere means the temperatures go up,” said the atmospheric scientist. “What’s complex is how the environment responds to it.”

The Arctic is rapidly warming — much faster than the global average. Alaska ecosystems are responding and changing in predictable and unforeseen ways.

This makes understanding the Alaska landscape of today and forecasting the Alaska landscape of tomorrow a tricky business. Yet it’s a challenge that three UAF researchers have accepted.

Bhatt is researching why the “greening” Arctic is also “browning.” Biologist Eugenie Euskirchen is looking at how to predict Alaska’s terrestrial ecosystems for the next 100 years. Doctoral student Rick Lader is forecasting Alaska’s potential to sustain agriculture should the Lower 48 fall short.

The three are sharing their insights about Alaska’s landscapes of today and tomorrow at the American Geophysical Union Fall Meeting 2017. Here’s what they had to say.

Is brown the new green?

Green used to be the Arctic tundra’s trending color.

The rolling, treeless plains dominate the northern reaches of Arctic lands with mosses, lichens, sedges and shrubs. The tundra is home to many rural communities and becomes an important birthing ground and nursery for wildlife in the summer.

More than a decade ago, UAF biology professor Skip Walker reviewed satellite imagery of the Arctic that measured the density of green in the Arctic.

He noticed that the tundra’s photosynthetic machinery grew from 1982 to 1998, a trend he dubbed as the “Greening of the Arctic.” Then another trend clearly emerged from satellite data that emerged starting around 1999. Large swaths of tundra were decreasing in biomass, in what became known as “browning.”

While “browning” is mostly a metaphorical term, it also has some literal implications, Bhatt said. She is collaborating with Walker and presented on the subject of greening and browning at AGU.

“In 2015, we noticed an earlier snowmelt and an earlier green-up on Alaska’s North Slope. Then there was a terrible frost because it was still winter. Many blueberry bushes browned, and they stayed brown all summer,” said Bhatt.

In earlier research, Bhatt showed how decreasing sea ice is contributing to Arctic greening. Now she is studying how extreme weather events, seasonal shifts and balance changes in the water cycle are contributing to the “browning.”

“Our next step is to organize a synthesis study,” she said. “We need bring together experts on permafrost, vegetation, climate, the ocean and other relevant areas of study.”

She added that it will take everyone’s expertise to unravel the complexity of how the Arctic is responding to the rather simple process of a warming climate.

Modeling from the tropics to the Arctic

Euskirchen has traveled to a remnant of the Bering land bridge that once connected mainland Alaska to Siberia during the ice age. While she admires the area’s history, she is even more interested in its future.

She has been helping scientists from the U.S. Department of Energy improve a long-standing terrestrial ecosystem model that scientists have been optimizing for Arctic tundra. DOE is funding the Next Generation Ecosystem Experiment, which aims to improve terrestrial models so that they can predict in detail how plant communities will evolve in areas especially sensitive to climate change.

But the Arctic is a far cry from other regions that lack permafrost and a long period of snow-covered ground. So Euskirchen and the team are tailoring the model to the natural processes of the circumpolar North.

“The model takes information that we know about the key processes that govern ecosystem functions like photosynthesis, respiration, carbon and nitrogen cycling and uses that information to predict how ecosystems will respond in the future,” she said.

The model can also run backward and show ecosystems of the past, which is a great way to test it if information about the past ecosystems is known. The scientists also hope the model might be able to predict future ecosystems that would essentially be brand new.

“They’re called non-analog ecosystems, meaning there’s not previously been an ecosystem like the ecosystems we’re moving into,” she said.

But the model is only as good as the information going into it, so Euskirchen and the DOE have spent some time in remote Western Alaska.

“We’ve been collecting field data, feeding the data into the model and then trying to determine which variables are most important for determining shifts in future vegetation,” she said.

This means getting down and dirty. They dig up soil samples and meticulously hand-count thousands of roots, including the tiny barely-there ones.

They also measure how much the leaves cover a given area and how much light they reflect, in addition to other traits.

Euskirchen hopes their hard work will pay off for Alaska’s future. While climate change is nothing new, human activities have accelerated it. This model may offer a window into next 100 years of Alaska and the pan-Arctic’s future.

Is warming an agricultural opportunity for Alaska?

Those who love Alaska’s farmer markets might be in for a treat if they can hang on until the end of this century.

Based on climate trends during the past 30 years, doctoral student Rick Lader projected what Alaska’s climate would look like for agriculture in the last 30 years of the 21st century.

He found the state’s overall growing season could be two to three months longer, with autumn frosts coming later and spring ones coming earlier. Precipitation could increase significantly and the state would spend significantly less time below the freezing point.

“A lot of the southern United States and Western United States is looking at lower crop yields due to excessive heat and in some cases drought,” he said. “In Alaska, the warming could be somewhat of an opportunity.”

He said an increase in farming in Alaska could make the state’s communities more self-sufficient.

So could Alaska produce prices eventually lower? Would bemoaning an empty broccoli bin at the grocery store be a thing of the past?

Whoa, slow down there, said Lader.

“This study is from a climate perspective,” he said.

It’s not a soil study; nor does it delve into other variables that make or break farming. While the changing climate in Alaska might be more amenable to farming, other challenges and hurdles exist.

Lader based his study on data collected from meteorological stations around the Lower 48 and Alaska. He also used climate science models to make climate projections fro 2071-2100. This work is part of his dissertation, which he will be defending in spring 2018.

“I chose to make projections for the latter part of the century, because it takes time for a signal of change to emerge from the year-to-year variability.”

And this signal seems to be loud and clear.