Shifting Baseline Syndrome

Featured Image: On the left is a restored wetland, in the center a berm blooms with native prairie species, and on the right is a large cornfield. Historically this landscape was blanketed with hundreds of thousands of square miles of wetland-dotted prairie. Today it’s almost entirely in agriculture. What is “normal” for the Midwest landscape? Agriculture or prairie wetlands? If both, in what ratio? Photo by author.

Main Article Reference: Soga, M. and K.J. Gaston. 2018. Shifting baseline syndrome: causes, consequences, and implications. Frontiers in Ecology and the Environment, 16(4): 222-230.


As a native Minnesotan, I know all the different types of snow – fluffy powdery snow, crusty snow, slushy snow, sticky snow that’s perfect for snowballs and tunnels, and of course ice, too. And though Minnesotans may agree on the different types of snow, opinions differ on what constitutes “a lot” of snow, or which winter months are the snowiest. This is because winters in Minnesota have changed dramatically in the past 50 years. My parents’ recollection of winter as a kid is much different than mine, which will be different even from kids’ born in the past decade. This “standard” of what we consider winter can also be thought of as a baseline. This baseline is shifting.

Minnesota is one of the fastest warming states in the US, with winter warming faster than any other season (13x faster than summer). Hence, my idea of a Minnesota winter is different than my parents’. The generational difference in the opinion  of winter is a phenomenon known as “shifting baseline syndrome” and it defines a gradual change in what is considered the ‘normal’ condition of the natural environment.

Shifting Baseline Syndrome

Shifting baseline syndrome is perpetuated when each new generation perceives the environmental conditions in which they grew up as ‘normal’. It also describes how people’s standards for acceptable environmental conditions are steadily declining. This phenomenon is not limited to climatic conditions, but also wildlife populations, water bodies, and entire ecosystems (forests, prairies, mountain landscapes). The term was first coined by a researcher who used it to describe fishermen’s baselines for healthy fish populations (Pauly 1995). He explained that each new generation of fisheries scientists and fishermen used the fish population levels at the beginning of their careers as a baseline by which they calculated harvest targets and measured population trends. When a new generation initiated their careers, the fish population levels had continued to decrease, but these levels served as the new baseline for this new group of fishermen and scientists. What emerged was a gradual shift in the baseline of fish populations, and thereby, a continual decline in population levels over time (Pauly 1995). This leads to our society’s tolerance of a creeping loss of fish species.

We have gradually tolerated the loss of many things in our environment – places, species, and resources. Of terrestrial vertebrate species, 322 (that we know of) have gone extinct since 1500 (Dirzo et al. 2014). We have also eliminated about one half of the planet’s undeveloped wilderness (Ellis et al. 2010). And just this past spring, a UN report estimated that one million plant and animal species are now at risk of extinction due to human pressures. But with quantities so abstract, it can be difficult to wrap your mind around the issue.

Fig. 1. Hetch Hetchy circa 1900. Photo Credit: Isaiah West Taber – Sierra Club Bulletin, Vol. VI. No. 4, January, 1908, pg. 211 [1], Public Domain,
To provide a more specific example, consider Yosemite National Park. There used to be a valley known as Hetch Hetchy so spectacular it rivaled that of Yosemite Valley (Fig. 1). Hetch Hetchy was Yosemite Valley’s “twin” to the north, and one of John Muir’s favorite valleys in California. He wrote: “…it is a wonderfully exact counterpart of the great Yosemite, not only in its crystal river and sublime rocks and waterfalls, but in the gardens, groves, and meadows of its flowery park-like floor” (Muir 1907). But most of us have never seen it, let alone heard of it. In 1923 it was flooded to create a reservoir to provide water to the city of San Francisco (Fig. 2). Even though it was located within the national park boundaries, an Act of Congress was passed authorizing the dam’s construction. If Hetch Hetchy had remained in its natural state, it might likely be as popular as Yosemite Valley is today. But most of our society has moved on from, forgotten, or never known that loss.

Fig. 2. Hetch Hetchy today. Photo by “Samuel Wong (wongsamuel)” – Own work, CC BY-SA 2.5,

The passenger pigeon, a bird species so common in the U.S. that its flocks blackened the daytime sky, is another example of Shifting Baseline Syndrome (Fig. 3). Passenger pigeons were native to North America and could be found from the Atlantic coast to the Rocky Mountains, from southern Canada to the Gulf Coast. This species was estimated to account for 25-40 percent of the total bird population of the United States; some estimate it was the most abundant bird in the world. Researchers believe there were once 3 to 5 billion passenger pigeons in North America prior to European settlement (Schorger 1955). But the species went extinct in 1914 from a combination of over-harvest and habitat loss. No one alive today has a memory to miss of this species in the wild. Our baseline for a diverse bird community does not include the passenger pigeon anymore.

We cannot appreciate what has been lost if we never knew it was there.

Fig. 3. An adult male taxidermied passenger pigeon. Photo by James St. John – Ectopistes migratorius (passenger pigeon) 5, CC BY 2.0,
Causes, Consequences, and Correcting the Shift

The theory of Shifting Baseline Syndrome is only a recently recognized phenomenon. Evidence abounds, but scientists are just beginning to better understand its causes and effects. A recent review identified the causes of changing baselines as a lack of experience, memory, and/or knowledge of past conditions (Soga and Gaston 2018). It is also known as “environmental generational amnesia” in the field of psychology (Kahn 2002). The consequences of Shifting Baseline Syndrome are a lowering of our standards for what we deem to be a healthy state of our environment. At the same time, we experience an increase in tolerance to environmental degradation (Soga and Gaston 2018). For those of us closely familiar with environmental change, another effect known as ecological grief can set in.

This shift in our standards is not intentional (though some may argue otherwise). However, there are ways we can correct the shift. The authors of the review recommended four main ways to prevent or reverse Shifting Baseline Syndrome:

1) Restore the natural environment. This primarily includes a “rewilding” effort that restores environments to their natural state (Fig. 4).

2) Monitor and collect data. Citizen science has the potential to play a significant role in helping us understand the state of our environment and how it is changing. Apps and programs such as iNaturalist, Bumble Bee Watch (Fig. 5), Monarch Model Validation Project, and the Great Backyard Bird Count encourage public participation and collaboration in gathering data on our natural world.

3) Reduce the extinction of experience. Increasing people’s direct experience with nature will help foster personal relationships and appreciation for the environment. Environmental education programs, hunting and fishing programs, and improved access to outdoor recreational areas are all avenues to help improve experiences with nature.

4) Thank you for reading this! Educating ourselves can help us better understand the appropriate baseline by which we should measure environmental change. It can also help us value our natural resources more and recognize loss when we see it.

Fig. 4. An example of rewilding: a restored prairie wetland in southern Minnesota occupied by a pair of trumpeter swans. By the year 1900 trumpeter swans were extirpated from Minnesota due to overharvest. In 1987 they were reintroduced by the MN DNR and now have a sustainable population in the state. Photo by author.
What is the Baseline?

The appropriate baseline is the pre human-modified condition of the landscape, ecosystem, climate, or species population. For instance, as an ecologist, most of the studies I read and produce have an introduction that includes some variation of the phrase, “Only 10% of the historic 25 million acres remain…” or “Today, less than 1% of the native ecosystem exists….” Ecologists have become very familiar with these historic baselines. But most reasonable ecologists also recognize there must be a balance between society’s needs and the needs of the environment. We know we cannot ever achieve the true baseline – that’s not the goal. The goal is to use it as a benchmark to assess change and assign value to depleting resources. Policies such as the National Park Service Act of 1916 (created our National Park system and was passed after the authorized damming of Hetch Hetchy), the Endangered Species Act (1973), and the Clean Water Act (1972), along with most other environmental regulatory acts, were designed as a form of long-term protection from some of the effects of Shifting Baseline Syndrome.

As the human population grows and demands on resources increase, there is an even greater need to stabilize our baseline for a desirable state of our natural world. Without this, our standards for a healthy environment will continually decrease. With a steady, accurate baseline, we can sustain more of our natural world and avoid significant losses like that of Hetch Hetchy and the passenger pigeon.

Fig. 5. Tri-colored bumble bees (Bombus ternarius) observed by this author and documented on both iNaturalist and Bumble Bee Watch. Photo by author.

Dirzo,  R., H.S. Young, M.  Galetti,  et  al.  2014.  Defaunation  in  the  Anthropocene. Science 345:401–06.

Ellis, E.C., K. Klein Goldewijk, S. Siebert, et al. 2010. Anthropogenic transformation  of  the  biomes,  1700  to  2000.  Global  Ecology and  Biogeography 19:589–606.

Kahn, Jr, P.H. 2002. Children’s affiliations with nature: structure, development, and the problem of environmental generational amnesia. Published in: Children and nature: psychological, sociocultural, and evolutionary investigations by P.H. Kahn, Jr. and S.R. Kellert. MIT Press, Cambridge, MA.

Muir, J. 1907. The Tuolumne Yosemite in danger. Published in The Outlook, A Weekly Newspaper, vol. 87, pp. 486-489. The Outlook Company, New York, NY.

Pauly, D. 1995. Anecdotes and shifting baseline syndrome of fisheries. Trends in Ecology and Evolution 10(10):430.

Schorger A.W. 1955. The Passenger Pigeon: Its Natural History and Extinction. Univ of Wisconsin Press, Madison, WI.

Soga, M. and K.J. Gaston. 2018. Shifting baseline syndrome: causes, consequences, and implications. Frontiers in Ecology and the Environment 16(4):222-230.

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Whitney Kroschel

Whitney Kroschel

I am currently a PhD Candidate at Louisiana State University in Baton Rouge, LA. My research interests are generally in the fields of plant ecology, seed ecology, and wetland science. My dissertation research is evaluating the effects of flooding on tree species composition in forested wetlands.

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