REBECCA ROBERTS, host:
For the next year, NPR and National Geographic are traveling the globe looking at how the climate is changing. We're also looking at the effects of those changes here at home.
Ms. SANDRA HENDERSON: Hi, my name is Sandra Henderson. Today in Erie, Colorado, my aspen burst into bloom, first bud burst. Bye.
ROBERTS: Sandra Henderson is a backyard botanist. And if you are one, too, there's a project called Project Budburst that needs you. It's a citizen science campaign to collect data about native plants. Observing nature's cycles is an ancient art called phenology, now a crucial tool in tracking the Earth's warming.
But as NPR's senior correspondent Ketzel Levine discovered, it can be as simple as smelling a lilac.
KETZEL LEVINE: My story also begins with the burst of a bud.
Prof. KAREN DELAHAUT (Farm-to-Market Specialist, University of Wisconsin): Hi, Ketzel. This is Karen Delahaut from UW Madison. It's 5:00 on Friday, April 27. And I'm here at the arboretum and just looked at the lilacs, and they're just about ready to pop.
LEVINE: The cue I've been waiting for to get to Wisconsin for lilac bloom.
Ms. DELAHAUT: So can you see them? Can you see them? Smell it.
LEVINE: Oh, yeah.
Prof. DELAHAUT: Yeah.
LEVINE: That's spring.
Prof. DELAHAUT: Isn't that nice?
LEVINE: I hope you can imagine the fragrance of a lilac. Get to a nursery quick if you've forgotten the scent. So powerfully stirring and reassuring that within a century of their introduction here, lilacs were synonymous with home.
However unwittingly, these non-native shrubs have had a great deal to say about how our climate is changing. It all started in the 1950s when a Bozeman, Montana, professor named Joseph Caprio used the lilac's bud and bloom times to map the advance of Montana's spring. By the 1980s, an entire lilac network stretched across the country. That network later morphed into the National Phenology Network, parent to Project Budburst.
Prof. DELAHAUT: It's a very purple day out here.
LEVINE: Yes, it is.
Prof. DELAHAUT: Now here's a lilac that we would call full bloom.
LEVINE: Karen Delahaut's real job here in Madison is at the university as a farm-to-market specialist. She'd make a great professor of phenology, too, except it's not a capital S science. Without cracking open a book you've already got what you need.
You start with a plant like the lilac, which has an easy-to-read life cycle. Then you record five very specific life events: first leaf, full leaf, first flower, full bloom and past bloom.
Prof. DELAHAUT: Yep. That's when I pull that notebook out in the car and I scribbled the date in there.
LEVINE: Then what do you do with it? Let's say you're doing that for 10 years, what do you do with your data?
Prof. DELAHAUT: Then I can see from year to year what's happening and is there a trend for earliness. It's definitely getting warmer.
LEVINE: She's right. Observations based in part on decades of lilac data now indicate that spring is arriving 6.8 days earlier in the Midwest than when Professor Caprio first began counting buds.
Now, it isn't only plants that speak to time and change. Insect hatching is a phenological event. For that matter, so is that first whiff of skunk.
Prof. DELAHAUT: Earthworms coming on the sidewalk in the spring. That indicates that the ground has thawed.
LEVINE: Monarch butterfly larvae eating milkweeds.
Prof. DELAHAUT: The first firefly flashing, which is typically sometime in July in Wisconsin.
LEVINE: The first cricket chirping, which speaks of more than just summer, its speed of chirp can tell the temperature.
Prof. DELAHAUT: You can still hear crickets in October, but they're going breep(ph), breep.
LEVINE: Phenologists did not set out to track climate change. Take a naturalist like Aldo Leopold, who lived here in Madison and kept meticulous records for the love of the natural world. His student and neighbor, James Zimmerman, hadn't a clue what his own records might one day reveal. But with a pencil stub in one pocket, index cards in another, he scribbled his observations in near hieroglyphics, much like the foot scratchings of a bird.
Ms. LIBBY ZIMMERMAN (Widow of James Zimmerman): June 27, 1978. Martins - that would be purple martins - robins, three or more singing, doves singing, crow calling…
LEVINE: Libby Zimmerman's husband died in the early 1990s, leaving behind 50 years of priceless observations as well as a philosophy of life.
Ms. ZIMMERMAN: If you go out in nature and you keep records, then you look. You want to know what birds are singing, you want to know what plants are blooming. And pretty soon, you find you begin to learn more and more about the nature around you.
Ms. KAY JENSEN (Farmer, JenEhr Farm): The dandelions were out, and Paul, my husband, and I were talking, and he was saying I'm not sure that the soil temperature is warm enough to be planting beans.
LEVINE: But to organic farmer Kay Jensen on the JenEhr Family Farm outside Madison, the weeds suggested otherwise.
Ms. JENSEN: No, I think we're ahead of time, I said. The dandelions are up so I think we should go check. Sure enough, he went off to the field, took the thermometer, put it in the ground six inches down. We were well above 50 degrees, and so we planted beans yesterday.
LEVINE: When elm leaves are big as a penny, you must plant kidney beans if you mean to have any, and corn should be knee-high by - you got it - the Fourth of July. But if spring is coming earlier, what will the new folklore be?
There is other music in these hills, wrote Aldo Leopold, by no means audible to all. Its notes the lives and deaths of plants and animals, its rhythms spanning the seconds and the centuries.
Ms. NIKKI ALMENI(ph): Hi, my name is Nikki Almeni (unintelligible) and I am 10 years old. And today I saw my Saguaro cactus start to bloom.
Unidentified Woman: In Tucson, Arizona.
Ms. ALMENI: In Tucson, Arizona.
LEVINE: And in Portland, Oregon, I'd like to report that the neighbor's lilac is 100 percent past bloom.
Ketzel Levine, NPR News.
ROBERTS: Find out how to start your own budburst investigation at npr.org/climate. While you're there, don't miss the videos about climate change from our partners at National Geographic, who produce "Wild Chronicles" for public television.
STEVE INSKEEP, host:
Now in full bloom, it's MORNING EDITION from NPR News.
ROBERTS: I'm Rebecca Roberts.
INSKEEP: Thanks for your help this week. I'm Steve Inskeep.