An email from the Smithsonian Institution popped up in Theresa Crimmins’ inbox over a December break about two years ago.

Crimmins was researching phenology — the study of how plants and animals respond to seasonal changes — for a book chapter she was writing, and had requested whatever information the institution could find.

To the average person, the document the Smithsonian had unearthed would have been unremarkable.

It is a nearly 600-page, 19th-century report containing a dizzying amount of entries spanning from 1851 to 1859.

This data was highly unusual in its detail. Most records like it are generic and only cover small regions. This one contained thousands of entries spanning over 200 species across North America, including exact blooming dates, when fruit ripened and when different animals migrated into an area.

Crimmins, the director of the USA National Phenological Network, reached out to colleagues across the country to see if they knew about it.

It was unlike any document they’d seen before. And it apparently had never been utilized.

Comparing the entries to data from today could draw an unprecedented picture of how climate change has affected when plants bloom over the last century and a half.

So Crimmins teamed with Robert Guralnick, curator of biodiversity informatics at the Florida Museum of Natural History in Gainesville, and researchers from the University of Florida to do just that. They released a study in October with their findings.

What they found was a vastly different natural world caused by climate change — one where some species today bloom nearly a month earlier than they did in the 1850s.

When the timing of species that rely on each other shift around, it can create an unsteady ripple through ecosystems — causing a myriad of unforeseen consequences like less pollination or food scarcity.

“I think what this is helping us understand is that we are very much in a period of active change,” Crimmins said, “and really things are drifting earlier.”

How century old data is informing the future

The Smithsonian Institution in the 1850s recruited hundreds of citizen scientists across the nation to track when they saw plants bud or grow leaves.

At the time, Florida had been a state for only six years.

The first Florida entry was for “Alligator,” a city that would later be renamed Lake City in Columbia County. Edward Ives recorded the first leaves growing on a “Red or Soft Maple.”

Another contributor from “Cedar Keys” in Levy County was named Augustus Steele.

Steele is likely the same man who helped found Hillsborough County years prior, according to a Tampa Tribune article.

Vital as the data would turn out to be, the document went unpublished for years because of printing scarcity during the American Civil War.

In 2023, Crimmins was tasked with contributing a chapter for a third edition of a book on phenology. The book’s previous edition briefly mentioned a phenological data collection network in the 1850s, but it was merely a footnote.

It was an opportunity, Crimmins said, to dig deeper. Still, she was floored when she received the full document from the Smithsonian and saw its extraordinary detail.

“I was like ‘Oh my gosh, that’s cool,‘” Crimmins said. “When you have actual direct observations like that, you can directly compare them to the same species and the same events in the present day.”

The project mirrors the work of the USA National Phenological Network. The group, created in 2007, uses a formal tracking program that collects and monitors plant cycles with the help of citizen scientists across the country.

A formula for the future

Scientists don’t know precisely how climate change influences plant cycles.

Researchers know plants are sensitive to cues, like temperatures, but why flowering and leafing varies across species remains a mystery.

As the planet warms from human-caused climate change, these cycles are further muddied.

Guralnick and other colleagues from the University of Florida, including a small group of student interns, spent weeks scraping data from the 19th-century document.

Beyond comparing dates of blooming, they wanted to create a better framework to predict how species respond to climate change.

The October study outlines a revamped formula for predicting when plants will grow buds or leaves by adding an extra variable to how phenological predictions are typically made.

They found that with the added variable, their predictions more accurately aligned with how climate change has affected nature over the past century and a half.

With climate change, not all species are changing in the same way, or in the same direction, Crimmins said.

The northeastern part of the country is warming faster than the southeast, for example.

While the October study does not use Florida records (researchers used data as far south as around Georgia), there are some takeaways for the state.

Guralnick said species in the southeast are more sensitive to phenological cues, like temperature or rainfall changes.

Had warming in the south occurred at the same rate as the north, southerly plant cycles would be more affected.

“I think it’s neat,” Guralnick said. “It talks about these different layers, and so now we can predict if more warming happens here over time, we would see stronger phenological responses to that warming.”

When a plant blooms earlier than expected, that’s where mismatches among species that depend on each other can happen, Crimmins said.

If a plant buds before a pollinator arrives, the plant may not be able to reproduce as widely, and it could cause the pollinator’s population to decline.

Crimmins said the phenology network is a way to show how the natural world is changing and document it.

“There’s a lot people can do just with the data coming … but when we can also put into the context of what was happening a hundred or more years ago, with this particular data set, it’s even more powerful,” Crimmins said.

“It helps us to tell an even more robust story of how things have changed.”