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Ideas

In this patch of forest, climate change already happened

How a 1990s trip to Sweden inspired a living laboratory

By Eric Niiler

The idea first came to Jerry Melillo nearly 30 years ago, as he drove down a highway in Sweden, where he was attending a scientific conference. He noticed that, even though a blanket of snow covered the surrounding fields, the roads appeared ice-free.

Melillo asked around and discovered that in the winter, the underside of the roads were electrified by thick underground cables.

“They made a really robust resistance cable that could take a real beating,” recalls Melillo, an ecosystem scientist at the Marine Biological Laboratory in Woods Hole, Massachusetts. “I realized it might be a technology we could use” — to help scientists understand the long-term effects of climate change.

Decades before the dire scientific reports and the climate-driven increase in natural disasters, Melillo and a colleague, inspired by those cables, hatched a plan for a kind of ecological time machine. They would create a patch of land, deep inside a Massachusetts forest, where the predicted warming of the Earth could be measured, controlled, and examined before it actually occurs.

Specifically, Melillo wanted to know whether warmed soils would release more carbon dioxide and other greenhouses gases that could speed up the process of global climate change. The world’s soils — which are made up of decomposing grass, leaves, and trees — contain two to three times more carbon than the atmosphere. Scientists worry that if this big carbon sink starts leaking, it could create an earth-to-atmosphere feedback loop that will warm the planet even faster.

So in 1991, Melillo ordered cables from Sweden and brought them to the Harvard Forest, a 3,700-acre research facility in Western Massachusetts that has been hosting scientists since 1907. He and a postdoctoral fellow buried them in the ground, hooked them up to an electrical outlet, and began monitoring the soil, launching a unique experiment that is still underway — and hailed as a training ground for the scientists who will address global warming in the future.

It was quiet and peaceful under the forest canopy, but there were tons of mosquitoes, attracted by invisible waves of carbon dioxide.

Some climate change science takes place in controlled laboratory experiments, or over decades of painstaking work out in the field tracking the tiniest temperature shifts in the oceans, air, and soil. Melillo’s 900-square-meter plot — one of many ecological research projects underway in the Harvard Forest — offers the best of both worlds: the efficiency of an experimental laboratory in the outdoors.

Dozens of graduate students, postdocs, fellows, and occasional journalists have cycled through the site over the years, each taking away a keener understanding of how science works and what the Earth’s future might look like. One of them was me, visiting in 2012 as a fellow with the Marine Biological Laboratory’s Logan Science Journalism Program.

To get to the tiny plot, we hiked about a half hour from an old farmhouse that serves as the Harvard Forest offices through a rolling forest. The living laboratory sat on a sloping grove of red maple, red oak, and paper birch. Half-buried stone walls were a reminder that this area was cleared farmland until the soil gave out and farmers pushed west for greener pastures sometime in the 1850s.

Since then, the eastern forest has taken over. It was quiet and peaceful under the forest canopy, but there were tons of mosquitoes, attracted by invisible waves of carbon dioxide spewing from the heated soil — as well as from humans like my lab partner and myself.

That day, we took soil gas measurements from the heated plot and compared them to the unheated control plot. For a non-scientist, it was an illuminating example of the kinds of detailed measurements that scientists around the world have to take every day, every season — for years on end — to get a handle on how the planet is changing.

Grace Pold, a graduate student at the University of Massachusetts Amherst, is a more seasoned researcher. The unique features of the site, along with advances in DNA sequencing, allow her to carefully sort out the various species of bacteria that decompose organic matter, and then trace the evolution of those bacteria in her laboratory.

“By matching their behavior and certain genes,” she says, “I can then make predictions about what microbes are going to respond to increased warming.”

Pold has collected soil samples through rain, snow, humidity, and attacks of gross-looking gypsy moths descending from the tree canopy above — all while marveling at the mix of wilderness and control.

“It’s lovely to go out there; you get to escape and go to the forest,” Pold says. “It’s also nice to have bathrooms at your field site, and somewhere to have lunch.”

The singular research opportunities at the field site have led to the publication of dozens of scientific papers in high-impact journals, — including a major paper in the journal Science last fall, which issued a dire warning about the carbon released from the soil.

And the site has helped launch successful scientific careers, such as that of William Peterjohn, the postdoc who helped Melillo bury a mile and a half of electrical cables in 1991. His first six months at the Harvard Forest led to the publication of his first scientific paper, which helped him land a job. He is now a professor of biology at West Virginia University, and an expert in how greenhouse gases and acid rain affect the forest and its inhabitants.

Despite its importance to the scientific community, the field site’s continued existence hasn’t always been a sure thing. “The first and most obvious challenge was finding enough resources year after year to keep the experiment going,” Melillo says.

First backed by the EPA, the project is currently funded by grants from the National Science Foundation and the Department of Energy. Melillo has to make the case to renew the funds every six years, and he’s managed to keep the project afloat through administration changes in Washington, economic downturns, and uncertain times for climate change research.  

Nature brings its own challenges. Several random lightning strikes have hit trees in the small plot, including one that knocked out a nearby control shed in 2005 that temporarily halted the project.

Through it all, researchers have continued to trek from the summer-camp-like field house, through the groves of leafy red oak and hemlock to this small, remote spot, where technology from three decades ago still gives them a glimpse of the future.

“What I like about the long-term warming experiment is that it has a life of its own,” Pold says. “Just as you think you are starting to understand, it changes again.”

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Eric Niiler is a writer based in Washington, D.C.

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