Global Warming and Acadia
In March Acadia National Park brought together more than 50 scientists in a series of workshops with the goal of identifying important Park research questions. When the scientists were asked what the Park should be doing now in anticipation of future changes and impacts, there was broad consensus that Acadia was likely to be changed in important ways by global warming.
For me, the persistent focus on global warming across the five workshops came as a surprise. After all, there isn’t a great deal that we can do at Acadia to change the course of global warming. Isn’t it a little like death and taxes? — something that will happen, to some degree, in any case, regardless of Park management decisions?
Well … yes … the mechanisms driving climate change work at a scale that extends far beyond this Park. But, as I learned from five days of listening and from subsequent reading, Acadia is, in many ways, an ideal place to study and watch if you want to understand the effects of climate change. Further, understanding those effects in detail could add to our understanding of this Park.
Making sense of this is easiest if you begin with a look at the different potential impacts of global warming at Acadia.
Sea Level Changes
The sea level has been rising for the past 150 years at a rate averaging between 1 mm and 2 mm per year. That rate has increased over the last decade or so. While there is considerable debate over how much the sea will continue to rise over the next 50 to 100 years (most predictions are for an increase of just under a foot to one of several feet by 2100), nobody is suggesting that the trend will reverse itself.
With the exception of the Park here in Schoodic, Acadia National Park is made up of islands. The most obvious impact of global warming and of the associated rise in sea level is that there will be less Park above water. A number of workshop participants suggested using GIS (Geographic Information System) tools to create maps that explore the various scenarios, as a way to anticipate the impacts of sea level changes and to focus research efforts on the places that will receive the earliest or most significant impacts.
As an example of one response to this problem, this summer a group of archeologists will use the Schoodic Education and Research Center as a base of operations for research in shell middens in areas outside the Park. The archeologists will document and catalog these cultural resources before they are destroyed by wave action and erosion as the water level rises.
The effects of a rising sea level differ for the various habitats in the Park. A number of workshop participants noted that the sea level rise is already resulting in a loss of wetlands. There are a couple of different causes for this. One is that roads and other human development along the coast–outside the Park as well as inside it–have the effect of "armoring" the coast–creating a barrier to wetland expansion as the sea level rises. With nowhere to go, the wetlands are simply submerged. In other cases, even where wetlands can expand landward, the increase in the water level is now happening so fast that the wetlands can’t expand quickly enough to keep up. An estuarine marsh ecosystem takes time to establish itself and to stabilize, and the relatively rapid increase in sea level isn’t giving the wetland system the time that it needs. They are drowned before they can grow.
Participants in the workshop focusing on physical sciences noted that Acadia is a relatively unique place from the standpoint of the land/sea interaction. There are very few areas along the Atlantic coast where the elevation changes so rapidly as the land meets the sea, and among this small number of sites, Acadia is unique in its protected status, guaranteeing researchers that they can follow changes over time. It is also a place where scientists have already done extensive work to document past sea level changes, with ancient coastlines now on mountainsides 250 feet above the current sea level. For these reasons, it is an ideal place to monitor sea level changes moving forward.
In the marine sciences workshop several scientists noted that changes in sea level would have significant impact on local currents moving around and between the islands that make up the Park. The directions and velocities of these local currents determine temperature and availability of nitrogen and food supplies for the different tidal habitats on the islands. When the currents change, the makeup of these plant and animal communities will change. Taken together, this set of physical and biological interactions is a rich area for study that could increase our understanding of the Park’s natural systems.
Climate Changes
One of the characteristics that makes Acadia special is its location in the transition zone between the northern boreal forest and the eastern deciduous forest. The Park’s ability to span and mix wildlife and plants from these two ecoregions is part of the explanation for the Park’s diversity of wildlife and habitat. It also means that the Park will be particularly sensitive to changes in temperature due to global warming.
Although nobody knows how the climate change will manifest itself here, it is likely that there will be earlier springs and more rain– with less snow in the winter months. Earlier springs, along with more freezing and thawing as a result of less snow cover, will have significant impacts on plant communities. This is true of aquatic plants as well as terrestrial ones. In some areas, in other countries, earlier springs and consequent greater warming of coastal waters has resulted in dramatically increased chlorophyll growth, with associated changes in plant and animal systems.
It is also possible that climate change will come in the form of a greater number of extreme storm events, which have their own impacts on the natural systems, in some cases accelerating change.
What to Do
The suggestions by the different scientists at these workshops were not focused on somehow stopping climate change. But they do include the notion of "preservation" in the sense of collecting information — whether that information is from an archeological site or about a plant community. The focus of the recommendations was on increasing the level of descriptive science to get a better understanding of what we have and of how things work now, in advance of the anticipated changes.
Take the probable changes in local currents as an example. We do not have a good picture of how water, nutrients, energy, an organisms move around and between the different islands in the Park archipelago. Suppose the sea level rises, and suppose that we find that there are substantial changes in the makeup and location of shellfish communities, seaweed, coastal fish stocks, and shore birds. In order to understand those changes, we would want to have a couple of things. One would be a historical record for its own sake. We would want to know what plants and animals existed before the change.
The second thing we would want would be an understanding of the new system. But, without information about the velocity, temperature, and directions of the currents before the change, we would be tremendously handicapped in trying to understand how the new, changed system emerged and developed. We would want to be able to look back, at the way things were, in order to understand what was new
So–both as a matter of preservation and to create a foundation for new understanding–we need to create a comprehensive inventory and understanding of the Park as it exists today..
With regard to the specific matter of currents, it turns out that Jessica Muhlin, a doctoral student at the University of Maine in Orono, is using oranges released into the currents around Schoodic Point to try to gain some understanding of these kinds of local circulation patterns — I will write more about her work in coming weeks. But Muhlin’s work is just a start. There is much more to be done before we could develop a comprehensive picture of the local circulation around the islands that make up the Park. And, beyond that, local currents are just one part — though an important one — of gaining a better understanding of the Park that we know and love today.
In short, the reasons to think carefully about how global warming might change Acadia National Park grow out of the Park’s traditional missions of preserving our heritage and of helping people engage with nature. We want to create a record for future generations of what we have before it changes. The record will have value in itself. But it will also provide us with the foundation that we need to better understand the dynamics of this complex, beautiful place.
Politics and Climate
Because climate change has economic impacts, there is an understandable interest in identifying the causes of the change and in mitigating impacts, if possible. Different understandings of the problem lead to different courses of action, with different effects on different interest groups. So, it should come as no surprise that global warming and climate change have political dimensions as well as scientific ones.
But the politics don’t matter as we look at the scientific questions here at Acadia National Park. Whether the sea level is rising because of things that people are doing, or whether it is rising due to factors unrelated to human activity, it is still rising. The importance and urgency of establishing baseline understandings of the Park’s ecosystems and of monitoring change is the same in either case.