A Hundred Years of Climate Data Is on the Verge of Withering Away

Kathleen Pryer did not watch March Madness this year.

That isn’t unusual in and of itself — Pryer describes herself as “not a basketball person,” though that might still raise a few eyebrows this time of year at Duke University, her place of employment. But the professor of biology has been a bit distracted lately. For the past few months, she’s been on defense, fending off a loss of her own: the pending closure of the school’s herbarium.

A herbarium (or plural, herbaria) is a collection of preserved plants, typically dried and mounted on sheets of rigid paper. The oldest existing collection in the world, the Gherardo Cibo herbarium in Rome, dates back to the mid 1500s; many U.S. collections are well over a century old. Browsing digitized herbaria online, one can easily get sucked in by their unintended whimsy; though the preserved plants are scientific specimens, traditionally collected by botanists to be used in the study of taxonomy during Western biology’s golden age of naming things, the pages remind me more of the pale, beautiful botanical illustrations in my childhood copy of Thumbelina.

Duke’s herbarium turns 103 this year and contains 825,000 specimens, making it one of the largest collections in the country. But back in mid-February, Susan Alberts, Duke’s dean of natural sciences, sent an email to Pryer, who curates the herbarium, and four other associated faculty members to inform them that “it’s in the best interests of both Duke and the herbarium to find a new home or homes for these collections.”

Though there had long been rumblings about the future of Duke’s herbarium — calls for “strategic plans,” hand-wringing about funds, worry about hiring new staff — the news came as both a shock and a slap in the face to the faculty, chief among them Pryer. “It’s some kind of little stinky plot,” she told me, adding, “I didn’t just roll over when it happened. I reached out to absolutely everybody I could think of.”

The news of Duke’s herbarium closure ricocheted through the tight-knit natural sciences community. Mason Heberling, an associate curator in the Section of Botany at the Carnegie Museum of Natural History, told me it should be a “wake-up call” for other researchers. The Duke herbarium is prestigious and hardly a “languishing collection,” he explained; researchers and faculty can easily slip into taking their herbaria for granted. “I’ve realized now that a huge part of my job as a curator will need to be explaining why these collections are important,” he said.

Swiftly, botanists and curators came to Duke’s defense. Opinion pieces and quotes decrying Duke’s decision appeared in the pages of The New York Times and Science. A petition went up on Change.org urging the school to reconsider its decision. Online fora burbled with discontent. “This may be the single worst thing to ever happen to Southeastern botany,” one post on Reddit read, with 64 additional comments piling on the administration for being “profit-obsessed business assholes.” “They could probably fund the entire thing with the salary of one head [basketball] coach,” grumbled another commenter.

The criticism of Duke’s decision is rooted in both a romantic nostalgia about herbaria — the same way you might feel fondly about hand-painted globes or cabinets of curiosities — and a very modern sense of scientific urgency. Researchers have only recently started leveraging the collections as invaluable pieces of data in the greater picture of climate change. “Herbaria are, in many ways, one of our best places to understand nature across space, time, and species,” Charles Davis, the curator of vascular plants at the nation’s largest private herbaria, at Harvard University, told me. “These collections are snapshots of events and occurrences in space and time that you just can’t easily replicate anywhere else. In fact, I would argue it’s impossible.”

Think of it this way: Worldwide, there are about 3,600 herbaria located in 193 different countries that collectively hold about 400 million specimens. Botanists estimate as much as half of the planet’s undiscovered flora could be found in herbaria backlogs. Barbara Thiers, the editor of the Index Herbariorum, a digital guide to the world’s collections, told me that when she was the director of the New York Botanical Garden Herbarium, “we had a huge room filled with unidentified species; I think there were 35,000 or 40,000 specimens in there.” That wasn’t for lack of effort — Thiers said that for many of the plant groups, there simply aren’t any working experts or published literature for curators to consult.

Because the climate is changing so fast, many plants in herbaria will go extinct before they’re formally discovered and named, a process known as a “dark extinction.” “It’s a very sobering feeling to touch the leaves of a tree that doesn’t exist anymore,” Erin Zimmerman, an evolutionary biologist and author of the forthcoming book Unrooted: Botany, Motherhood, and the Fight to Save an Old Science, told me, recalling coming across such a specimen in an herbarium while doing her own research. She likened herbaria to a library, but in her description I also heard echoes of a church: “The specimens are sometimes very old; you have to be very gentle with them, which just adds to the sense of holding something precious,” she went on.

Dwindling biodiversity is only the most obvious way herbaria are critical to 21st-century science. “Phenology, whether it’s when plants flower or when birds migrate, is one of the most important signals of climate change response,” Davis, the Harvard curator, said. Still, our long-term datasets aren’t very robust; research on how plants are changing with warming climates typically dates back only 25 to 30 years, tends to concentrate on the U.S. and Western Europe, and centers on easily observable phenomena, like the leafing out of woody trees. Researchers can turn to herbaria for centuries-old records of where certain plants grew and when they flowered, helping to bridge gaps in our understanding.

Heberling, of the Carnegie Museum of Natural History, tracks environmental changes in his research, but he didn’t start using herbaria until well after he’d obtained his Ph.D. Only then did he realize “herbarium specimens are incredible archives of the past,” he told me.

“You can look at the tiny pores, the stomata, on the leaves” of a plant in a herbarium and “see how that has changed over time with increased carbon dioxide,” Heberling said. Scientists have even used this method to create CO2 records.

Admittedly, climate science is still a relatively cutting-edge use case for the herbarium; according to Davis’ research, “global change biology” remains one of the least popular ways to leverage herbaria, well behind “taxonomic monographs” and “species distributions” that still dominate the field. Still, “there are things that, five to 10 years ago, I’d never even imagined we’d be doing today with herbarium specimens,” he told me.

As a result, Duke’s herbarium closure has made some question the university’s commitment to climate research — something that Alberts, the school’s natural sciences dean, emphatically refuted when I raised the question with her. She told me that a rough search revealed that only 23 of the 2,000 papers published by Duke researchers over the past few decades on climate change contained the word “herbarium” anywhere in them. “With my knowledge about all of the climate change research that’s been going on at Duke, the herbarium is not really central to whether or not Duke studies climate change,” she said.

For her part, Pryer has bristled at the administration’s insinuations that the herbarium is of limited use to students and faculty on campus. “You don’t measure a collection by who uses it,” she told me. “As I’ve been naughty enough to say, it’s not a toilet. People outside — the global community — uses it. That’s how you measure its value; things like 90 refereed publications a year [across all disciplines] cite the Duke collections.” Pryer can quickly tick off the climate projects that have come through the herbarium’s halls, including her recent supervision of a local high schooler’s research paper that found the pink lady’s slipper is flowering in the area 17 days earlier than it used to.

Duke is “not an appropriate home for a herbarium that is this large and valuable” for a number of reasons, according to Alberts, ranging from the need to hire new faculty to manage it (Pryer and several of her colleagues are approaching retirement) to the collection’s current building needing renovations. “I have had people email me saying, ‘I know you have enough money, I know you have the facilities.’ I’m like, ‘I’m sorry, you should tell me who you’re talking to, because we don’t,’” Alberts said. She added that she plans to be personally involved in finding the right home for Duke’s herbarium over the next several years.

After all, it’s not like the potential untapped climate records in the Duke collection are being destroyed (though both Pryer and Davis told me they’ve had deans wonder aloud if they could be, since many herbaria are now digitized). The goal is only to move the collection somewhere where it might be better utilized.

Thiers, though, said this is exactly what makes the natural science community so alarmed. As the collection is split up, ideally, the Index Herbariorum would record where Duke’s specimens get sent so scientists can still find them. But when new collections absorb the materials, curators will weed out duplicates, sending unneeded pages elsewhere — at which point specimens can fall between the cracks. “Before you know it, individual specimens will be lost,” Thiers said. “I can almost guarantee that as these secondary moves happen, people will not keep up with the database records.”

There is also a worst-case scenario everyone seemed nervous to mention: that Duke’s collection, in whole or in part, will end up in storage somewhere. Herbarium specimens are extremely susceptible to insect damage and must be kept in expensive, climate-controlled cabinets and rooms. “If they’re putting boxes in a storage storeroom someplace, they’ll be worthless in no time,” Thiers warned. The unidentified plants and uncollected climate data — all of it could be lost. And the cruelest part? Scientists wouldn’t even know what they are losing; it’s a dark extinction of a dark extinction.

When I spoke with Alberts, she said there were no updates on the administration’s plans for the herbarium. She expressed sympathy, though, for the faculty who oppose the administration’s decision. The herbarium “is their life’s work, and it’s important that they have a voice in this process,” she said.

Pryer is determined to keep fighting, even if this isn’t exactly how she’d pictured spending her golden years at Duke. “It’s having an impact on my research and on my health,” she told me. “It’s been pretty unrelenting. I’m anxious for something to resolve.”

She looked tired. There was a faculty meeting later in the day, and she hoped she’d be able to get more clarity about the administration’s decision then. “I don’t want this to go on forever,” she said. “But I also don’t want there to be a decision that makes Duke look insane.”