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You're listening to Short Wave 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 short -waver who's curious about how nature is changing, how to pay attention to the land around us, and how to make every day, Earth Day, which sometimes looks like taking a walk around your neighborhood.
Shai Sore 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 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, Shai 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.
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Welcome to short waves Nature Quests garden edition this is our kickoff episode and I am here with producer Hannah Chin, who's going to tackle Shy's questions with me.
Hi, 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, et cetera.
It's called phenology.
Phenology 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 -requesting.
They were. They were nature -requesting.
We posted notices on listservs, 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 Thoreau's records?
And we said, like, what records?
The 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.
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 leaf out 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 10 days earlier now than in Thoreau's time.
And the reason that they're flowering earlier, 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.
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.
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 Daley.
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 Shai 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 then 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.
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 normals.
So, a climate normal, you can consider that as being kind of like your baseline average temperature precipitation.
And so there are averages.
And then we average those over a 30 -year period.
So, there are 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.
Okay, so now we're getting really granular.
You know, I talked to some local experts about Shi's question, including Jim Farr.
He's a master gardener in Alameda County, which covers Shi'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.
Like, they thought it was later in the year than it was because it was so warm.
So warm. Wait. So, did your local experts have any advice for Shai?
Just to be aware of how plants are experiencing a changing climate through observations and 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.
Ooh. And it lists plants that will 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. Like, these local excerpts, these national excerpts, 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.
Even Thurow. Even Thurow.
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 dataset 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 NatureQuest with me, Hannah.
No problem, Emily. Thanks for having me.
Short wavers! NatureQuest 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 your 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 Collin Campbell is our Senior Vice President of Podcasting Strategy.
I'm Emily Kuang. And I'm Hannah Shin.
Thanks for listening to Short Wave from NPR.
Edward Jones, member SIPC.
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