Planning for Possible Futures in Acadia National Park

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In celebration of Acadia National Park's 102 birthday, we're exploring how the Northeast CASC is helping the park plan for future climate conditions.

July 8 marks Acadia National Park's 102nd birthday. Established by President Wilson on July 8, 1916 as Sieur de Monts National Monument, it was changed to Lafayette National Park in 1919, and renamed Acadia National Park ten years later. In celebration of America's first national park east of the Mississippi, we're exploring how the Northeast CASC is partnering with the park's managers to prepare the park and its natural and cultural resources for future climate conditions.

Lighthouse on rocky shore

Bass Head Harbor Light Station, built in 1858, is the only lighthouse on Mount Desert Island and is listed on the National Register of Historic Places. Credit: The National Parks Service

Situated along the rugged coast of Maine, Acadia National Park is the country’s oldest national park east of the Mississippi. Hiking trails and historic carriage roads wind their way through spruce-fir forests and stands of oak, maple and beech trees. Granite ridges and mountains - including Cadillac Mountain, the highest point on the North Atlantic seaboard - rise above the cobblestone beaches that are so characteristic of Maine’s coastline.

As little as 14,000 years ago, Acadia was covered by a massive ice sheet. The chiseled landscape that exists today is the result of retreating glaciers, rising and lowering seas, and the persistent battering of wind and waves. Now, Acadia is undergoing a new period of transformation. Temperatures are warming and precipitation patterns are changing. The park is experiencing more hot days, longer-lasting heat waves, more frequent and intense heavy rains, and reduced snowpack. While we know these changes are occurring, we are less certain about what climate conditions will look like in 10, 50, or 100 years. How much more warming will we get? How intense or frequent will severe rainfall events become? How will the park’s plants, wildlife, and infrastructure fare as a result of these changes in climate? And perhaps most importantly, how can park managers prepare for the coming changes, when so many variables remain uncertain?

Planning for an Uncertain Future

In parks across the country, the NPS is implementing a technique known as scenario planning to help managers assess risk, test decisions, and develop strategic plans for a range of possible futures. Scenario planning originated as a military strategy used to identify possible threats from opponents and to test different responses to those threats. Scenarios have since been widely adopted by the business world to help companies make decisions under uncertain future economic, social, and political conditions. Today, managers across a range of sectors, including land and resource management, are using scenario planning to help guide management practices and protect resources in the face of climate change.

"We all know the benefits of planning ahead in our daily lives. Having a ‘Plan A’, ‘Plan B’ or ‘Plan C’ helps us to be prepared no matter what the future brings. Scenario planning is based on the same idea."

These scenarios are essentially plausible stories about future climate conditions and the potential impacts on ecosystems, infrastructure, and other resources. This information can then be used by managers to determine the best course of action for protecting key resources under each alternative scenario. While scenarios are not predictions, they do provide managers with a structured way to plan for a range of possible futures. In Acadia, researchers with the NPS Climate Change Response Program, the NPS Northeast Region, and the DOI Northeast Climate Adaptation Science Center helped park managers determine which future scenarios should be considered in their resource management plans, so that they can begin devising strategies to address each possible future now.

“We helped the park come up with a contingency plan for each possible future,” said Dr. Alex Bryan, a climatologist with the Northeast CASC and project team member. “We all know the benefits of planning ahead in our daily lives. Having a ‘Plan A’, ‘Plan B’ or ‘Plan C’ helps us to be prepared no matter what the future brings. Scenario planning is based on the same idea. Scenarios tell managers what they should keep an eye on, so they know which plan to implement and aren’t surprised by future conditions.”

Identifying Acadia’s Possible Futures

Table showing projected changes in key variables over the next 25 years for each Acadia climate scenarios.

Table showing projected changes in key variables (number of hot summer days, number of cold winter days, summer precipitation, inland & coastal storms, sea-level rise) over the next 25 years for each Acadia climate scenario. Up arrows denote increasing trends, down arrows decreasing trends and sideways arrows indicate no change. Arrow size denotes amount of change. Scenario 1 is split into ‘early’ and ‘late’ phases of the scenario. Comparisons are made to conditions from 1993-2013. Modified from Star et al. (2016)

To develop scenarios for Acadia, the team first examined how weather affects the park. Situated on the coast, threats such as stronger hurricanes, sea-level rise, and storm surge are a big concern. In the past, the rate of sea-level rise was one inch every hundred years. Today, it’s nearly ten times that, and is projected to continue to accelerate. Floods resulting from elevated storm surge and heavy rains could wash out the historic gravel carriage roads and cause culvert failure. And these impacts can be costly – in 2008, Hurricane Hanna cost the park over $200,000 in damages. Rising temperatures are also challenging park managers, who are facing increasing pressure to open the park earlier and close later in the year than normal.

“Based on these concerns and current challenges, we knew that our scenarios needed to focus on rainfall intensity, warm season temperatures, sea-level rise, and storm surge,” said Bryan. The next step involved combining these key variables and visualizing the different ways they might change in the near-term future, focusing in particular on the next 25 years. The result was a set of four storylines, each depicting a different way the future might play out. “These scenarios focus on the aspects of climate change that affect Acadia the most, so that we can help park staff cope with the challenge of managing under variable and uncertain future conditions,” said Bryan.

One scenario projects mild warming with dry summers; another projects more intense warming with much drier summers. Another, more complex scenario, projects a period of temporary cooling followed by intense warming. This scenario, dubbed “Calm before the Warm”, represents the natural variation in the climate system, which can be difficult to plan and manage for. It’s also possible that Acadia could experience a blend of these scenarios – they’re not necessarily discrete. However, as Bryan explains, by examining each scenario independently, the park will be more prepared for each scenario, should any or all aspects of them come to fruition.

From Storylines to Management Plans

Once the scenarios were developed, the team held a workshop for park staff. “We walked them through the scenario planning process and discussed how the climate has changed in recent years and its impacts on the park so far,” Bryan explained. “We then asked the staff to consider what each of the four scenarios could mean for the park’s ecosystems, infrastructure, and operations. Then, park staff examined Acadia’s current management protocols to see what might need to be changed and what didn’t.”

For example, park staff identified the potential need to purchase extra gravel so they will be able to quickly rebuild carriage roads in the event of more intense hurricanes. They may also want to test different plant species to see which ones could best survive in a warmer climate, and increase monitoring of invasive plants and insects, which could encroach as temperatures rise. “The Emerald Ash Borer, a beetle native to Asia, has been spreading northward and killing off various ash species – and it’s now on Maine’s doorstep,” Bryan said.

Park staff have already begun using the scenarios to inform planning efforts, according to Becky Cole-Will, Chief of Resource Management for the NPS at Acadia National Park. “We are currently using the scenarios to help select planting techniques and species for a vegetation restoration effort on Cadillac Mountain, one of the park’s most visited sites. We are also testing our plans for managing transportation park-wide and for managing natural and cultural resources in the intertidal zone, to see how our plans hold up against the different scenarios and to identify potential points of vulnerability within our plans.”

While the degree of uncertainty surrounding future climate conditions can be overwhelming, this exercise demonstrates that it doesn’t need to be a barrier to action. As Bryan notes, “scenario planning is a simple yet powerful tool. It allows managers to take steps now to proactively plan for the future and to respond quickly to change as it occurs.”

Continuing on the Path Towards Adaptation

While the scenario planning project has wrapped up, the Northeast CASC is continuing to collaborate with Acadia National Park to support climate adaptation. Jennifer Smetzer, a Second Century Stewardship Fellow, and Toni Lyn Morelli, a USGS Research Ecologist with the Northeast CASC, are starting a new project to identify locations in Acadia and the surrounding region that are buffered from changes in climate that might be occurring on the broader landscape. Known as “climate change refugia”, these areas can act as short-term sanctuaries for plants and animals. The team is working to identify the climate and habitat requirements for a selection of species, then will map areas that might serve as refugia for these species in the future, as climate conditions change. Smetzer and Morelli are actively engaging local stakeholders at Acadia, and more broadly throughout the region, to identify a path forward for integrating climate change refugia into management and climate adaptation plans.