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Let’s Talk About Trees

December 20, 2016

Photo of graduate student Uday Kunwar Thapa coring a tree in Nepal.

Photo of graduate student Uday Kunwar Thapa coring a tree in Nepal.
Graduate student Uday Kunwar Thapa coring a tree in Nepal.

Before we get into the connection between climate change and the liberal arts, let’s start by talking about Alexander von Humboldt. He was a Prussian explorer and scientist from the 1800s who influenced everyone from Charles Darwin to Henry David Thoreau. Regarded as one of founders of modern geography, Humboldt had a huge impact on how we understand the world around us.

Photo of geography professor Scott St. George
Professor Scott St. George

Although relatively unknown in America today, his name is everywhere. He has a penguin, a flower, a river, a mountain, a park—even a town in Minnesota—named after him. There’s also the Humboldt Foundation in Germany, which gives out research awards each year to experts from the natural sciences and humanities. That brings us to Humboldt aficionado and geography professor Scott St. George. An earth scientist in the College of Liberal Arts, St. George has been named a Humboldt fellow for 2017.

"The Humboldt Fellowship fosters international collaboration among scientists, but it’s named after a geographer," says St. George. "A lot of the concepts we take for granted about Earth’s climate didn’t really exist before Humboldt developed them. And he was one of the first people to make scientific connections between society and the natural world."

As a Humboldt fellow, St. George will spend most of 2017 at the University of Mainz in western Germany, collaborating with fellow dendrology researchers who focus on tree rings and the clues they hold about climate change. They'll be studying how and why certain places in the world go through prolonged climate shifts, with a special focus on "megadroughts" (St. George recommends this Atlantic article).

"Megadroughts are droughts that last for several years," explains St. George. "There are certain places in the world that seem to be prone to them, from sub-Saharan Africa to the southwestern United States, and they create massive challenges for water resource management and agricultural productivity."

Visit our image gallery that includes photos from the Dendrochronology Center's trip to Nepal.

Existing weather records go back only a few decades, which isn’t long enough to fully assess the threats posed by megadroughts. In order to predict the risks these climate shifts will bring in the coming decades, we first need to understand what caused them in the past.

This is where trees come in handy. Many trees live for hundreds or thousands of years, so they provide a longer-term perspective on the changing environment than weather records alone.

"Trees are a little bit like nature’s weather stations," says St. George. "They take information about temperature, rainfall, and other factors and record it within the physical structure of their rings and the chemical structure of the wood."

As part of the Humboldt fellowship, St. George and his German colleagues will use a global network of tree-ring data to estimate the risks of megadroughts. "Anywhere where you have old trees, somebody has gone there in the last 20 or 30 years and collected samples. This project is trying to pull all of that information together to look at the northern half of the planet all at once," he says.

The Humboldt project comes on the heels of another, related study in Nepal. With funding from a Talle Faculty Research Award, St. George and his graduate student, Uday Kunwar Thapa, spent the past summer collecting tree samples from the central Himalayas.

The climate in Nepal is changing more rapidly than any other part of the planet outside of the Arctic. Yet, while it’s clear that the region is becoming warmer, it’s difficult to know what impact that will have on future water resources. By collecting tree-ring samples from pine forests in eastern Nepal, St. George and Thapa are trying to learn what the climate was doing prior to the weather records, which often date back only to the 1980s.

Whether he’s observing tree rings from the Canadian Rockies, the eastern Himalayas, or the forests of Europe and beyond, St. George hopes to identify the physical processes that cause a region’s climate to become stuck in a wet or dry phase.

"Once we have a record that goes back some 300 years, we’ll be able to help people who live in that area make better decisions about how to manage their water and forest resources," says St. George. "We’re like historians, except instead of studying human history, we’re studying the history of nature."

It’s the kind of geography adventure that would make Alexander von Humboldt proud.