Climate Change & Nantucket Part 1: The Effects Go Far Beyond Rising Seas And Erosion

Editor's note: The 2024 Nantucket Climate Change Summit is this Wednesday, Sept. 4. As the island begins to implement the nearly $1 billion in projects outlined in its Coastal Resilience Plan, while the town and Land Bank envision a major overhaul of Washington Street along the harbor, and private land owners and organizations contemplate their own responses to climate change and rising seas, the Current is publishing a three-part series this week on the impacts of climate change on Nantucket, the island's response, and potential solutions. Enjoy part one below and stay tuned for part two on Wednesday. 

The daffodils are blooming too early for Daffodil Day, hydrangeas around the island spent most of the last summer dead and flowerless, and ticks are more abundant than ever. These may seem like separate issues, but they share the same cause, at least in part: climate change.

As an island surrounded by rising seas and exposed to ever-stronger storms, Nantucket is particularly vulnerable to climate change. And erosion isn’t the only problem to worry about.

While the effects of warmer air and water are rarely as dramatic as a collapsing bluff or floodwater pouring down Washington Street, they may be just as worrying and even more all-encompassing, impacting everything from fish to flowers. As the oceans warm, fish move north, changing the stock available near Nantucket. And flowers, which often use temperature cues to determine when to bloom, emerge earlier, throwing the timing of festivals like Daffodil Day into doubt. Meanwhile, cranberries ripen later—perhaps even too late for the Cranberry Festival—as it takes longer for temperatures to cool in the fall.

Dr. Sarah Bois, director of research and education at the Linda Loring Nature Foundation, knows this as well as anyone. The foundation, she says, has been studying the effects of warmer weather on plants for years. But not because they are worried about Daffodil Day. There are much more serious ecological problems that arise when plants bloom earlier in the season.

“Every plant has different strategies for getting pollinated and dispersing its seed, and it's not like a strategy it decides on,” Bois said. Those strategies rely on different pollinators, which may be responding to cues that have nothing to do with temperature. If the flowers bloom and the pollinators they rely on aren’t around yet, that’s a problem.

“The relationships that have evolved between these species over millennia can be broken down by changes in the climate,” Bois said. “We’re not going to see one species get completely killed or wiped out. What we’re going to see is diminishing returns for different plants. Species might be less robust and more vulnerable to other threats.”

“We’re seeing such a shift in how things are interacting,” added Jen Karberg, director of research and partnerships at the Nantucket Conservation Foundation. “That has cascading impacts on the ecology of the island.”

One plant that is particularly vulnerable to changes in temperature is eelgrass. Though it doesn’t rely on pollinators, warmer ocean temperatures can stress and even kill the plant.

“That’s the big one in some ways because eelgrass is such a keystone species for that ecosystem,” said Emily Molden, executive director of the Nantucket Land and Water Council. “We definitely stand to see a lot of detriment from these rising water temperatures.”

Eelgrass slows erosion, reduces flooding, and provides a habitat for many species, including scallops, making it a key part of the health of Nantucket’s waters. Since 1994, a third of the island’s eelgrass has died. Studies suggest many reasons for this decline, including nitrogen from fertilizers that wash into the harbor, but one is warmer waters.

Some species, like the harmful algae that choke local ponds in the summer, thrive when temperatures increase, but they form an uninviting group. Its members include ticks, cockroaches, clothing moths, and poison ivy—the last of which Bois described as the “superstar” of climate change.

“We’re noticing more of certain insects, more of certain diseases,” said island landscaper Steven Collette, who works for Ernst Land Design, said. “There’s always something new for us to worry about.”

Collette has no doubts about what is causing the uptick in pests.

“It’s all driven by the fact that it’s getting warmer,” he said. Usually, cold winters freeze pests like ticks and kill them. Now, not so much.

“We’re not losing populations of pests the way we used to,” he said.

Invasive species, many of which posed little threat to their native competitors when the climate was cooler, also often do well when temperatures increase. From English ivy to Scotch broom, invasives are crowding out native species around the island and taking over ecosystems. Lone Star ticks, which can make their hosts deathly allergic to red meat, may have also migrated to the island as a result of climate change. As their numbers skyrocket, sightings have gone from noteworthy to routine. Soon, they may be nearly as ubiquitous as deer ticks, who themselves thrive in the warmer weather.  

Temperatures don’t increase uniformly, however. A warm January can be followed by a cold February, leaving plants unprepared and vulnerable to frost. It was exactly this set of events that damaged so many of Nantucket’s hydrangeas last year.

Precipitation follows a similar pattern. Nantucket has seen several severe droughts in recent years, increasing the risk of dangerous wildfires and killing some sensitive plants. Overall, though, rainfall on island is actually increasing. It’s just that instead of falling uniformly across the year, the rain comes all at once.

“We’ll have drought, drought, drought, and then our soils are dry, and then we have a significant rain event, maybe a Nor’easter or something like that, in the winter that drops a whole lot of precipitation at the same time,” Bois explained.

That’s the perfect recipe for a flood. The water can’t soak into the ground fast enough, so it fills the streets and pours into basements. And since the soil is dry and loose, the water drags huge amounts of dirt with it, massively increasing erosion as it flows, eventually, into the ocean.

From floods to droughts and flowers to fish, climate change impacts nearly every facet of life on Nantucket. Even when those impacts are invisible, even when they happen slowly over decades, they still change the island.

“Everything,” Karberg said, “is just becoming a little bit more extreme.”