Short Wave - Nature Quest: Are Flowers Blooming Early?

Episode Date: April 22, 2025

Welcome!! This is the first episode of Nature Quest, a monthly Short Wave segment that answers listener questions about your local environment. This month, we hear from a listener in California who's concerned that the flowers in his neighborhood are blooming way, way earlier. Is that normal? And is climate change the culprit? Short Wavers Emily Kwong and Hannah Chinn investigate.Got a question about changes in your local environment? Send a voice memo to [e-mail] with your name, where you live and your question. We might make it into our next Nature Quest episode!Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave.See pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

You're listening to Shortwave from NPR. Hi everyone, Emily Kwong here, and welcome to a brand new segment that we're calling Nature Quest, where every month we'll bring you a question from a fellow shortwaver who's curious about how nature is changing, how to pay attention to the land around us, and how to make everyday Earth Day, which sometimes looks like taking a walk around your neighborhood. Shy Soar is a social worker in Oakland, California. he works in the hospital system, and during the pandemic, he started doing sessions remotely. Between appointments, I would be walking the neighborhood to get some fresh air, to clear my mind,

to just, like, move my body. And, you know, I think that started me just being more aware of the, like, nature in the neighborhood. Wildflowers, plum trees, California poppies. Shai technically lives in East Oakland, so this is Northern California. and this winter has been warm. So like the 70-degree weather in December and January that I ran away from in L.A. was starting to happen here. So that's the first thing I noticed.

I'm like, no, this is not what I wanted. And it's not just the warmth that he's worried about. On a walk in early January, shy noticed that the tree at the end of his driveway, a calorie pear tree, was blooming. the California poppies too. And Shai was worried. Because it was only January, these flowers typically bloom in March and April. And I'm like, this doesn't feel right. What's up with that?

Okay, maybe I should ask the experts. So today's nature quest, gardens. How the local changes Shai's noticed are connected to a bigger shift in the seasons. What does a warming climate mean for the timing of trees and flowers and the people who love them? You're listening to Shortwave, the science podcast from NPR. Welcome to Shortwave's Nature Quest, Garden Edition.

This is our kickoff episode, and I am here with producer Hannah Chin, who's going to tackle Shai's questions with me. Hey, Emily. Hi, Han. Okay, what did you find? What is going on? Well, okay, so I didn't know this before I started reporting this episode, but it turns out there's a whole field just devoted to studying this timing of flowers and trees, etc. It's called phenology. Penology just generally means the timing of biological events.

So it refers to the migration times of birds, when butterflies start flying in the spring, when plants flower, when trees leaf out. So these are all part of phenology. That's Richard Premack. He's a professor of plant ecology at Boston University. And he runs a lab that specializes in plant phenology. So the cycles of budding and flowering and how those cycles have shifted over time. And one of the most powerful ways of doing this is finding historical records and matching them with modern observations. Historical records of, say, when plants flower, or when birds migrate or when ponds melt in the spring.

So ideally, you would want to find a set of records where someone started 100 or 200 years ago and continued it up to the present time. Okay. I mean, do we have any records like that? Well, 20 or so years ago, biologists didn't know. Like, this field of phenological research was still really new. So Richard and the rest of his team in Boston were like, do records like this even exist in the United States? My mother told me, if you ever want to know anything, you just ask everybody you know for information. And eventually someone will tell you what you're looking for. So they started asking everybody they knew.

Like, hey, we're looking for these kinds of records. Do you know anywhere that we can find them? They're requesting. They were nature questing. They were. They were nature questing. We posted notices on blisters, electronic bulletin boards,

supermarket bulletin boards, and libraries. There are a lot of natural history clubs in Boston. We went to these natural history clubs, and we stood up, and we told people what we were looking for. It's like they were looking for a lost dog. Yeah, except they didn't even know if these records existed, so it's like if they were looking for a hypothetical dog. And this friend of ours, who was an environmental philosopher,

at one point said, well, why don't you look at Therose records? And we said, like, what records? But Henry David Thoreau, the naturalist, the philosopher, Thoreau. That's him. So when Thoreau wrote Walden, he lived in the woods and conquered Massachusetts for a little over two years. He kept his journal. Famously, yes. And apparently, he also kept very detailed plant blooming records.

Oh. These tables were really unknown to biologists, but they were very well known to Thoreau scholars. But when we saw these unpublished tables, as soon as we saw them, we knew that they were fantastic. Because, Emily, these tables recorded the first leafout and flowering times of more than 500 plant species during an eight-year period in the 1850s. Jackpot. Thoreau, who knew the transcendentalist scientist among us? Okay, so when they compared Thoreau's tables to what we see now, what did they find? Generally speaking, the trees are leafing out about two weeks earlier now, and the wildflowers are leafing out about eight to ten days earlier now than in Thoreau's time. And the reason that they're flowering earlier and the trees are leafing out earlier is because it's warmer.

Richard says overall, the weather is about four to six degrees Fahrenheit warmer than it was 150 years ago in Thoreau's time. And this warmth, these changes, they aren't just happening in Concord. It's happening across the United States. It's happening across Europe. It's happening across the world. Plants are flowering earlier, trees are leafing out earlier. And just to be clear, Emily, not all of these shifts can be attributed solely to climate change. The urban heat island effect, where streets and building surfaces retain and absorb heat, that also affects plant timing. Artificial light can trick plants into thinking the days are longer than they are. And both of these things make trees and plants in big cities bloom earlier and then lose their leaves later. That makes a lot of sense. The conditions in cities, city environments are such that plants are just behaving very differently than they would in the suburbs or out in countryside.

Totally. Plus, there's other data that backs up the shift in overall plant timing, which, by the way, affects gardeners and farmers, too. A lot of these gardeners and farmers use something called the USDA plant hardiness zone map. Yeah. I think I've seen these zones printed on the back of seed packets, right? These are the maps that help growers figure out which perennial plants will thrive in a certain location. Yeah, exactly. And this plant hardiness zone map, it's been around for a really long time.

But the thing is that it's really just based on one single statistic. The idea is for the map to show the coldest minimum temperature, nighttime temperature, that you might expect to get each year averaged over a period of years. So it's like, on average, how cold is that coldest night of the year? This is Chris Daly. He's the principal author of these plant hardiness zone maps, and he says that sometimes shifts in the map are due to better data or more updated technology. Some years are warmer than others and some are colder. Basically, any changes in the plant hardiness zone map might not be totally indicative of large scale climate change. That's a really important thing to understand. It means that the plant hardiness zone map, the gardening zone map might be less good at reflecting what should. shy is talking about how the growing conditions in his area are changing overall. Yeah. But before we give up, Emily, I do want to tell you about a different set of maps,

maps that are publicly accessible, that do track the weather conditions overall and show how they're changing. They're called climate normals. When you're listening to a weather forecast and they say temperatures are going to be above normal tomorrow, what does that mean? So it's not normal. It's not just a number or just something they're pulling out of their hat. It's actually a specific statistic that we use. Chris doesn't just do the USDA maps. He's also in charge of something called the PRISM Climate Group at Oregon State University. That group collects data from volunteers and weather stations across the country about all the average temperatures and precipitation levels every single day. And they

map it all out. Okay, every gardener needs to know about this map. What is this map called? It's called the prism climate normals, and we'll link it in the show notes. A map across the country is made up of little pixels, a grid of pixels, and each pixel is about 800 meters, about half a mile on the side. It's pretty small. So we have something like 80-some-odd million pixels across the country that we're mapping every day. Wow. Yeah, it's pretty impressive. So for each tiny half-mile square, Chris and his team take the average temperatures to get daily normals, they get monthly normals, and they get these 30-year climate. normal. So a climate normal, you can consider that as being kind of like your baseline average temperature

precipitation. And so they're averages. And then we average those over a 30-year period. So they're averages of averages. And so they're pretty stable. And what does it reveal? Is there any particular trend? Chris told me, yes. He says looking at this data and how it's changed over time, it's really clear that the area east of the Rockies is getting wetter and the southwest is getting drier. And overall, just across the board. Temperatures are going up. Yeah. Okay, so now we're getting really granular. You know, I talked to some local experts about Shai's question, including Jim Farr. He's a master gardener in Alameda County, which covers Shai's area. Looking at weather data from the nearby Oakland airport, Jim said there was a combination of rain and unseasonably warm temperatures in

January. And that stretch of 70-degree days that Shai was noticing was enough to trick plants like poppies and calorie pear trees to bloom early. Oh. Like they thought it was later in the year than it was. Yes. Because it was so warm. So warm. Wait.

So did your local experts have any advice for shy? Just to be aware of how plants are experiencing a changing climate through observations and things like the PRISM Climate Normals map you mentioned, UC Davis Arboretum and Public Garden Horticulture team actually has a climate ready gardening toolkit. And it lists plants that. We'll do okay under climate change. You know, plants that are like locally drought resistant or climate resistant in some way. We'll link that in our episode notes too. Yeah, that's so cool. Emily, I think the other thing that's cool is that all of these scientists are basically doing

the same thing that Chai is doing intuitively, right? True. These local experts, these national experts, they're all keeping track of their environment and then noting changes that they see and then comparing those changes to what existed in the past. It's like everyone can do science. thorough. Even thorough. And if you want to go on your own nature quest, it's really easy. By documenting your local observations on apps like Inaturalist and Nature's Notebook, you're helping scientists like Richard keep track of widespread changes in the environment. Yeah. Or you can volunteer to monitor the weather and the precipitation where you live

and help contribute to the data set that makes those climate normals we mentioned possible. We'll link to a few of those programs in the show notes. Sounds good. Thank you for going on this nation. Nature Quest with me, Hannah. No problem, Emily. Thanks for having me. Shortwavers, Nature Quest is our new, monthly, earth-loving series, and it is built around you and on the changes you're noticing in the world around you. So send us a voice memo with your name, where you live, and your question. And we might make it into a whole episode. This episode was produced and reported by me, Hannah Shin. It was edited by our showrunner,

Rebecca Ramirez, and fact-checked by Tyler Jones. Becky Brown was the audio engineer. Beth Donovan is our senior director, and Colin Campbell is our senior vice president of podcasting strategy. I'm Emily Kwong. And I'm Hannah Chin. Thanks for listening to Shortwave from NPR.