On Sunday, Feb. 2, Punxsutawney Phil saw his shadow, predicting six more weeks of winter. Despite his prediction, spring officially begins on Thursday, March 20. But Phil might be surprised to learn that, due to climate change, spring has been arriving earlier in recent years. 

While some people may welcome the early onset of spring’s pleasant weather, this trend is disrupting natural processes that have evolved over thousands of years. 

To better understand how climate change is affecting spring, Temple Now caught up with Jocelyn Behm, assistant professor of biology in the College of Science and Technology. Behm works in Temple’s Integrative Ecology Lab (iEcoLab) housed in the Center for Biodiversity. At the iEcoLab, Behm leads research that investigates how humans and invasive species are affecting biodiversity. 

Here’s what she has to say about climate change’s effect on spring and the natural processes tied to the changing season. 

Temple Now: How is climate change affecting spring? 

Jocelyn Behm: Climate change does a lot of things, but the main, consistent pattern that we see is that spring is arriving earlier, because it’s warmer. Climate change is doing other things too, like altering rainfall patterns and wind patterns, which we’re seeing this year. If it’s exceptionally dry or exceptionally rainy, that can also affect the timing of spring. 

TN: What effects are these changes having on ecosystems, generally? 

JB: If we just look at temperature, as it gets warmer, certain plant species might start blooming earlier in spring. That’s not true for all plant species—the issue with climate change is that different species respond differently. And then other species might also be sensitive to temperature in different ways, like birds and bird migration, or insects coming out of their dormant state for the winter.  

If you think of a natural ecosystem pre-climate change, everything had evolved so that the timing all matches up. The birds are coming back at the same time that the insects, which the birds feed on, are emerging. The flowers bloom at the same time that the bees are emerging, so that there are pollinators for the flowers and food for the bees. There is all this synchronous matching, and that’s what is starting to break down because all the species are responding in their own unique ways. 

TN: What effects are we seeing in our local ecosystem? 

JB: There have definitely been changes in flowering times, with different flower species flowering earlier. Many of the spring wildflowers in our forests—like pink lady’s slipper, marsh marigold and wild geranium—are flowering earlier each year due to warmer temperatures. Their goal is to flower in early spring before trees grow new leaves, so that they can take advantage of the open canopy and get access to valuable light. Interestingly, new research is showing that many of our forest trees, like our maples, oaks, hickories, elms, etc., are even more sensitive to spring temperatures than the wildflowers are, and are advancing their spring emergence faster. This means that the gap for wildflowers to bloom before trees grow their leaves is shrinking, potentially putting some wildflower species at risk.     

At the iEcoLab, we study the spotted lanternfly, an invasive species in our region and one that is sensitive to temperature. They spend the winter as eggs and hatch in the spring. Depending on how warm the spring is, that can potentially affect when they emerge and hatch from their egg cases.  

We’re also seeing some shifts in bird migration patterns—when birds start coming back from their migration overwintering grounds. This affects both forest species, like the wood thrush, and more urban adapted species like robins. 

TN: Are these changes affecting humans in any way? 

JB: It’s certainly idiosyncratic in that it depends on the year. Recently, we’ve had some really hot, dry years, and that has affected crop production. Maybe not necessarily in the spring, but throughout the growing season through the summer and fall in this region for sure. I interact with several local farmers, and they’ve had a lot of trouble and many crops, like berries and lettuces and other crops, don’t do as well in certain years. There are definitely regional effects on food supply here. 

TN: Does that mean that spring isn’t the only season being affected by climate change? 

JB: From a scientific perspective, spring gets a lot of the focus with respect to climate change, and rightfully so. We’re seeing a lot of changes in spring. But fall gets neglected, even though there are a lot of temperature, precipitation and climate-dependent things that happen in the fall that are also affected by climate change, like when trees drop their leaves. Birds also migrate in the fall. All of those patterns are also shifting.