Studying Climate Change in the Alaska Tundra—and in a CU Denver Lab

The Alaska tundra—at the point where the ocean laps against land—is a wonderland of vegetation. At the lowest elevations, the wetland soil is soft and squishy. If you move inland, the land is taken over by lush grasses, sedges, dwarf shrubs, and forbs, a flowering plant. As you climb away from the ocean, step by step, sphagnum mosses cover the ground on a pillowy surface, so you feel like you’re walking on a giant sponge. 

In the midst of this bountiful vegetation, a lot is going on that you can’t see, including a constant exchange of gases in the atmosphere, weaving through vegetation, water, and soil. It’s a robust, complicated, and fragile system—and it is the focus of a National Science Foundation-funded research project led by Katharine Kelsey, an assistant professor in the Department of Geography & Environmental Sciences in the CU Denver’s College of Liberal Arts and Sciences.  

“Our overall question is: How is climate change affecting this part of western Alaska?” said the project’s lead principal investigator, Kelsey. “And, particularly, how will those effects potentially feed back into the local climate system?” The researchers are studying this by looking at the effect of sea level rise in a remote part of Alaska where a low-lying coastal delta meets the Bering Sea. Because the area is at a low elevation and a low relief, a very small change in sea level—from melting sea ice, storms, and other factors—can impact a large amount of land and the things that rely on it to grow and thrive. The research may also provide insight into how local environmental changes can have a global impact on the migratory patterns of animals and other ecosystems.  

Field Experience for Students 

This summer, a crew of people, including several CU Denver students, traveled to Alaska to study all this by literally getting their hands dirty. Using small plastic barriers—what Kelsey compares to a kiddie pool—the researchers marked off sections of tundra. Then, they used firehoses to pump saltwater from a nearby slew into the barriers to create a very small flood simulation to see its impact on the flora, fauna, and soil.   

The pump allowed them to simulate various ecological scenarios: sudden, prolonged, and repeated flooding. Some plots weren’t flooded, and some got passive warming chambers (basically, mini greenhouses) to simulate the impact of temperature change. “Then we sit back and watch,” Kelsey said. “Every day, our researchers, including our students, go to each plot and look in detail at what plants are growing. How big are they? What are the gas fluxes in response to all of these different treatments?”  

They brought some of the soil back to CU Denver to be studied in a laboratory—a crucial part of diving deeper into the research. “What we can do in the lab, that’s difficult to do in the field, is actually to change the salinity of the water,” Kelsey said. She explained that this allows them to see how the soil responds to different conditions, providing information on how plants and wildlife will react to create a more comprehensive picture of potential impacts. 

An “Ecosystem Approach” 

This research highlights the interconnectivity of lab and field work, as well as the collaborative atmosphere of the Alaskan delta. “We are taking an ecosystem approach to looking at this environment,” Kelsey said. “We know that flooding and warming are the largest impacts the ecosystem will likely see. And so, we’re imposing both of those future changes—separately and together—and then trying to really observe every ecosystem response so that we can really paint the picture of how the entire system will respond to these changes that we expect to see within years to decades.” 

Much like you can quickly tell the difference between fresh and salt water, plants can, too. A massive storm that floods a freshwater delta with saltwater—even temporarily—can alter a landscape and impact flora, fauna, and wildlife. Early data from the project suggested that the community composition of the vegetation can also change, meaning that the mix of plants can shift as some varieties survive and others perish. “The response of one plant is interesting, but the response of the community is what we’re particularly after,” Kelsey said. “And we’re seeing that in some cases, that response can happen pretty quickly.” 

As the vegetation community adapts, other impacts can occur. “This landscape…is a major hotspot for migratory birds, especially waterbirds,” she said. “This landscape not only provides a habitat for them, but they actually can function as ecosystem engineers in this environment. It’s a two-way relationship.” 

Kelsey said she hopes the research also provides insight into how changes in temperature, flooding, and vegetation could impact migratory pathways as food options change, shift, or don’t grow in the same places. All of this could impact ecosystems around the globe.  

Asking and Finding Answers 

Kelsey emphasized that another essential aspect of the research is ensuring that the information is shared with and built on by working with the local community, including the Yup’ik and Cup’ik peoples (the research was conducted on their historic lands and with their permission). “We have another component of our project that is focused on really sharing both this scientific process and the results of the work to [local] elementary school students,” Kelsey said. “And we are working with a videographer and elementary school teacher education specialist to produce lesson plans that are focused on the vegetation species that grow here and the types of environmental change that these students are seeing when they look out the door every day.”  

CU Denver has partnered with Utah State University and South Dakota State on the project, and the researchers’ preliminary findings from three years of fieldwork and lab experience show that greenhouse gas emissions are being impacted by flooding and salinity. “Greater salinity increases ecosystem emissions of carbon dioxide but decreases ecosystem emissions of methane,” Kelsey said. “Our results indicate that future flooding by saline water will have the largest effect on greenhouse gas emissions from low elevation wetlands, rather than the higher elevation tundra. 

But that’s just the start of this research’s findings. That discovery process—asking and finding answers—keeps Kelsey engaged in this work. “What brought me to the field was the opportunity to do work that got me outside, got me to beautiful places, and got me asking questions about the natural environment,” Kelsey said. “What kept me here was when I started realizing the intense gratification and excitement that comes from beginning to answer your own questions about the natural environment.”