Climate change is causing spring to arrive earlier and earlier, posing a challenge for plants and animals — as well as the scientists who study them. An early thaw can throw off the rhythms of nature, causing flowers to blossom before bees arrive to pollinate them, or spurring birds to head north before the ice has melted at their destination. Scientists looking to catalogue these changes are faced with a difficult job. They must track hundreds of species across thousands of miles, year after year after year, to understand how nature is responding to the rise in temperature.
To complete this task, they are asking for your help.
Anyone can collect data. Sheila Salmon, 85, used to set up libraries in New York City public schools. Now that she’s retired, she likes to document the lives of plants inhabiting the New York Botanical Garden, a hobby she took up after seeing an ad in the botanical garden’s newsletter. “It said, ‘Citizen scientists wanted, no science knowledge needed.’ And I said, ‘That fits me,’” she recalled.
Salmon’s observations, along with those of thousands of other volunteers, are being collected by the USA National Phenology Network (USA-NPN), a collaboration between the federal government and the University of Arizona. Phenology is the study of seasonal changes in nature — when flowers bloom, insects take flight, fruits ripen, birds migrate and leaves change color. Every year, people from all across the country contribute to its citizen science program, Nature’s Notebook. Since its inception in 2009, nearly 12,000 people have submitted observations, and volunteer data have been used in close to 50 peer-reviewed publications.
“In many other countries, phenology networks have existed for decades — in some cases, a really long time — and the information that has been collected through those organizations has been really valuable for scientists to better understand how the timing of different life cycle events has changed over time as different climate factors have changed,” said Dr. Theresa Crimmins, assistant director of USA-NPN. “The scale of what we’ve been able to collect is something that is well beyond what any individual researcher could ever accomplish.”
If you want to help collect data on seasonal changes, visit the Nature’s Notebook website, create a profile and find a local species of plant or animal to track from the list provided. The associated smartphone app will guide you through the process. “What we recommend is that you choose something to observe that’s really convenient. I observe a couple of trees in my backyard,” Crimmins said. She encourages volunteers to record regular observations year after year to understand how species are responding to changes in weather.
Volunteers tend to be nature lovers, plant enthusiasts or birders, many of them retirees, like Salmon. Some belong work with a group, such as a school or a gardening club. The top collectors have submitted thousands of readings. The all-time leader, Cathie Bird, a retired psychotherapist from eastern Tennessee, has logged more than 80,000 observations.
USA-NPN vets volunteer data for accuracy — entries are flagged, for example, if a species appears outside its known range — and it uses the data to build and test computer models that map the onset of spring based on the local temperature. USA-NPN runs one model that tracks honeysuckle and lilac blooms across the United States. The model is based on data collected over a few decades.
“We are now using incoming observations to verify whether the model is still performing well in those different parts of the country,” Crimmins said. She said that USA-NPN is using new data from Nature’s Notebook to build models for other species, including one that tracks changes in fall leaf color. “We just haven’t gotten to the point of those models being robust enough that we’re putting them into production and making maps yet.”
The data make clear that spring is showing up earlier and earlier, which is throwing off nature’s timing. That’s because some plants and animals emerge when the weather gets warmer, while others resurface when the days grow longer. In a typical year, these phenomena roughly coincide, but climate change is creating a mismatch, causing some species to emerge before the plants or animals they depend on have shown up. Birds, for example, lay eggs when insects are set to emerge, so there is enough food available to feed their young. If birds lay their eggs too soon, or insects arrive too late, hatchlings suffer.
This phenomenon, known as “season creep,” has consequences for humans too. The prompt arrival of spring is causing flowers to bloom early, extending allergy season. For farmers, shorter winters are creating all manner of problems. Early springs are shortening the period during which maple trees yield sap, for instance. Warm weather is harming apple production too. A balmy spell in early March can cause apple trees to blossom early, only to whither in a late-season cold snap.
Volunteer data is needed to build the computer models that will help people prepare for these changes and, further, to understand long-term shifts in the Earth’s climate. In perhaps the best example of a citizen scientist making a difference, researchers at Boston University compared present-day observations of plants in Concord, Massachusetts with notes recorded by Henry David Thoreau some 150 years ago. Inspecting those observations side by side, they could see quite clearly the long-term impact of climate change.
Today’s citizen scientists are performing much the same role as Thoreau, venturing to parks and backyard gardens to record the subtle changes in seasons — and to revel in what Thoreau called “the tonic of wildness.” That’s what draws volunteers like Shelia Salmon to the work of cataloguing nature.
“What keeps bringing me back is the wonderful change from my apartment on 32nd Street and 2nd Avenue, where I have the roar of the traffic day and night. It’s lovely to take the train, come across the street, walk into the garden,” she said. “There is a lovely kind of peace and gentleness.”