Tag Archives: nature-based solutions

The “Shifting Baseline Syndrome” Concept Can Apply to Ecosystem Process Rates

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David P. Turner / July 16, 2025

Sea otter consuming sea urchins.  Photo Credit: matt “smooth” thooth knoth through Flickr via Creative Commons License.

Introduction

The Shifting Baseline Syndrome (SBS) holds that successive generations of natural resource managers tend to have a different image of what is natural. 

The concept was originally proposed by a fisheries biologist (Daniel Pauly) who observed it in the context of declines in commercially harvested fish populations.

The obvious management significance of SBS is that population targets for restoration of natural ecosystems might be too low.

Here I will visit application of the SBS concept to ecological processes rather than just state variables like population size and biodiversity. 

First though, I note that one might ask if the term “baseline” even has meaning anymore.

We know that virtually all natural processes are now altered by human actions to some degree.  Also, that anthropogenic climate change and the 6th Extinction will play out over centuries, and will be largely irreversible.  Everything measurable about ecosystems is shifting, hence in some sense there are no baselines.  Which makes it a good time to hone in on how best to use the SBS concept. 

Case Studies of SBS in Relation to Ecological Processes

1.  Effects of Predation in Terrestrial and Marine Ecosystems

“Trophic cascade” effects of losing the upper trophic level in an ecosystem are common in terrestrial, as well as marine, ecosystems but are not always obvious. 

A land manager coming anew to Yellowstone National Park in the 1980s  ̶  after extirpation of wolves  ̶  and encountering overgrazing along streams, might not appreciate the regulatory role of wolves on the elk population (a major herbivorous species).  The baseline for the process of predation on elk had shifted, but the land manager might miss it.

A survey of kelp abundance along the coast of the Pacific Northwest US in the late 20th century would have found little kelp.  This form of marine plant is of great ecological importance because it provides food and protection for young fish.  A major control on kelp abundance is the presence of sea urchins.  They prowl the ocean floor and consume dead and live kelp plants.  A major control on sea urchin abundance is predation by sea otters.  The otters are able to overcome sea urchin spines and feast on their internal organs.  Unfortunately, sea otter fur is quite valuable and the otters in the Pacific Northwest were hunted to local extinction by around 1910.  As a consequence, urchin barrens  ̶  where little kelp is found   ̶   have formed from an overpopulation of sea urchins, with corresponding effects on fish populations.  As kelp faded from the near shore environment in the 20th Century, wildlife managers may have begun to think kelp was naturally found only at low density in these waters (a case of SBS).  Restoration of sea otter predation on sea urchins, and better management of other sea urchin predators, is helping recreate more vibrant, kelp-friendly, marine ecosystems. 

2.  Effects of Declining Invertebrate Diversity on Decomposition

Ecosystem ecologists commonly study rates of leaf litter decomposition by enclosing fallen leaves in a mesh bag and leaving the bag on the soil for an extended period.  The rate of change in dry weight is then a metric for decomposition rate.  One might assume that the results of a litter bag study reflect natural or baseline conditions.  But such is no longer the case.

A critical factor that is moving this bar is the “insect apocalypse”.  The process of decomposition (i.e. decay of foliage, roots, wood) is driven in part by invertebrates such as insects and slugs, and the process is slowed by a decline in invertebrate biodiversity. 

Driving forces in the decline of insect biodiversity include land use change, pesticides, and effects of climate change.  Desynchronization in the interactions among insect species, and between insect species and local plants, can significantly impact local populations.

Slowed decomposition means slower release of nutrients and possibly slower plant growth.  Thus, by altering state variables such as the diversity of invertebrates, we are altering critical process rates, possibly on a massive scale.  But detecting and tracking these rate changes is difficult.

3.  Effects of Deforestation on Regional Evapotranspiration

Large areas of the Amazon Basin have been deforested in recent decades.  A key process altered by deforestation is the transpiration of water, i.e. loss of water through leaf stomata.  Where canopy leaf area is decreased, transpiration decreases and because around 50% of precipitation in a rain forest is recycled from previous rain events (by way of transpiration), the loss of forest leaf area associated with regional deforestation tends to induce a decline in regional precipitation.  Decreased precipitation in the Amazon Basin is projected to impact native vegetation and agriculture.

The principle of “stationarity” in climate research is similar to that of “baseline” in ecological studies.  Climatologists aspire to describe the statistical properties (e.g. mean and variability) for properties like precipitation and temperature for a given region.  The climate is designated as stationary if these statistical properties are stable over time.  If those properties are drifting, as in the case of fossil-fuel-emissions-driven climate change, the climate is said to be non-stationarity and hence less predictable.

If ecological baselines are shifting and the climate is losing stationarity, natural resource managers require strong monitoring programs to track changes, and new adaptive strategies to avoid ecosystem degradation.

Conservation Strategies in the Face of SBS

A growing awareness of shifting ecological process rates, and the possible consequences, has helped inspire several conservation strategies.

Rewilding

The original “rewilding” concept emphasized “cores, corridors, and carnivores”.  Advocates pointed to degraded ecosystems and attributed the problem to the decline or absence of specific processes, e.g. predation.  The full range of trophic interactions was seen as fundamental to shaping the structure and function of ecosystems and landscapes.  Human interventions such as hunting were not considered a substitute for natural processes such as predation.

The reintroduction of wolves to the Yellowstone region is an iconic case of rewilding.  But the theory has also been applied in the case of background processes like decomposition.  Here, transfer of invertebrates and microbes from undisturbed to disturbed sites helps restore decomposition rates. 

The theory of rewilding is still under development but a core principle is to keep ecosystems “wild” – meaning to insure the continuous operation of all natural processes needed to drive the self-organization that is characteristic of complex systems.

Nature-Based Solutions (NBS)

Large areas of land and ocean provide services to humans – notably food, wood, water filtration, and recreation.  These working ecosystems are clearly no longer natural, yet they contribute to biosphere metabolism and are worth managing as such.

Human interventions and impacts are often altering these ecosystems, sometimes with limited reference to natural processes e.g. the full range of impacts form cattle grazing on public rangelands in the western US is poorly understood.  An NBS management approach aims to restore and monitor core ecological processes needed to provide ecosystem services to humans and to support thriving ecosystems as parts of the biosphere.

NBS is a conservation framework with an “overarching goal to address global societal challenges”.  It tends to be applied at large scales and require significant human management intervention.  On the human side, delivering ecosystem services and comprehensive stakeholder involvement are core objectives.  On the ecological side, the emphasis is on management of natural processes.  Restoration and management of mangrove forests is a good example because it requires intensive site manipulation that ultimately provides services like carbon sequestration and coastline protection from storm surges.

Both private sector and public sector efforts at sustainability are increasingly framed in terms of a nature – centered perspective.

Conclusions

Anthropogenically-driven non-stationarity in the physical environment, and shifting baselines for both state variables and ecological processes, are increasingly relevant to natural resources management.  Conservation frameworks like rewilding and Nature-Based Solutions provide adaptive strategies for managing under these contemporary conditions.  Governmental support for monitoring and restoration at multiple scales is required.

Human Impacts on the Global Carbon Cycle: Signs of Madness and Signs of Hope

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David P. Turner / December 19, 2021

Earth System Science has come to a remarkably good understanding of the global carbon cycle in recent decades.  The various pools (stocks) of carbon have been quantified (e.g. vegetation, soil, and atmosphere), along with the annual fluxes from one pool to another.  A key revelation has been that the quantity of carbon dioxide (CO2) in the atmosphere is increasing and that the increase is driven by anthropogenic factors (fossil fuel combustion and deforestation). 

Since the rising CO2 concentration is associated with a trajectory towards dangerous climate change, humanity has slowly moved towards commitments to reduce CO2 emissions.  Some types of emissions are more glaring than others, and this blog highlights four of the most egregious examples (signs of madness). 

Likewise, there are many technical and policy options for reducing CO2 emissions or speeding CO2 uptake, and this blog highlights four of the most promising (signs of hope).

Signs of Madness

1.  Oil from Tar Sands. Given the goal of reducing anthropogenic CO2 emissions as quickly as possible, an obvious candidate for termination is extraction of oil from tar sands (Figure 1).  The whole process of extracting hydrocarbons from the Earth and refining them has an energy cost, with related CO2 emission.  Unlike conventional oil, which comes out of the ground ready for the refinery, tar sands hydrocarbons must be mechanically extracted in a bulk form that includes many contaminants.  This material is then heated to isolate the oil component, a treatment requiring substantial energy – usually provided by combustion of natural gas.  The net effect is a 15% higher overall emissions of CO2 per gallon of gasoline coming from tar sands compared to conventional oil. 

Human Impacts on the Global Carbon Cycle. Open pit mine in the tar sands oil fields of Alberta, Canada
Figure 1. Aerial photograph of open pit mine in the tar sands oil fields of Alberta, Canada.  Image Credit: Dru Ojo Jay, Dominion

2.  Tropical Zone Deforestation.  About 10% of anthropogenic CO2 emissions comes from tropical zone deforestation.  The driving factors are primarily conversion to cattle ranching, industrial and subsistence agriculture, and tree plantations (Figure 2).  In 2021, the rate of deforestation in Brazil rose 22% and Indonesia cancelled a billion-dollar agreement with Norway to reduce deforestation.  Besides direct CO2 emissions from burning and decomposition of residues, the destruction of intact forests means removal of an on-going carbon sink since most forestland is now gaining carbon as part of normal growth or accelerated growth from CO2 fertilization. 

Human Impacts on the Global Carbon Cycle. Deforestation.
Figure 2.  Deforestation in the area of the Caguan River, Brazil.  Image Credit: NASA

3.  Supersonic Passenger Jets.  United Air Lines has announced plans to operationalize a fleet of supersonic passenger jets around 2029.  Their virtue would be cutting flight times across oceans by about half (they generally aren’t used over land because of sonic booms).  Their downside is a factor of 2.5 to 7 increase in carbon emissions per passenger mile.  In theory, their engines could burn sustainable aviation fuel but there are many issues with scaling up production of this fuel if demand increased substantially.

4.  Bitcoin’s “proof-of-work” Mining Protocol.  Bitcoin is a cryptocurrency that has a particularly energy intensive mode of operation, and much of the energy is from fossil fuels.  New digital coins are mined (created) by a competitive process in which multiple computer processors race to solve a computationally intense problem.  Only one computer wins, meaning that 99.9% of energy use and associated carbon emissions are wasted.  Current Bitcoin electricity consumption is on the order of consumption by a small country.  Alternative “proof-of-stake” approaches used by other cryptocurrencies are much less energy intensive.

Signs of Hope

1.  Natural Climate Solutions (NCS).  The land surface is currently a net sink for carbon dioxide, even after accounting for effects of deforestation.  Most of that carbon accumulation is showing up in live wood (Figure 3), thus it is tracked by global forest inventories.  However, a significant amount may also be accumulating in global soils (in part because of CO2 fertilization of plant growth).  The aim of the NCS strategy is to maintain all existing land carbon sinks and foster new carbon sequestration by way of altered land management.  Besides stopping deforestation, and reforesting large tracts of previously deforested land, NCS (more broadly Nature-based Solutions) will operate in the agricultural sector, wetlands, and grasslands.  Scientists estimate that NCS could provide up to 30% of the reduction in CO2 emission needed to hit net zero emissions at the global scale by 2050.

Human Impacts on the Global Carbon Cycle. Carbon accumulation.
Figure 3.  Old-growth forest at the H.J. Andrews Experimental Forest near Blue River. Image Credit: Oregon State University.

2.  Product Certification.  World leaders made a commitment at COP26 to reduce deforestation and end it by 2030.  A major player in that effort will be nongovernmental organizations that certify forest products as being produced sustainably, notably not in association with deforestation.  Products driving deforestation – and covered to a greater or lesser degree by certification – include wood, beef, leather, soybeans, and palm oil.  The science of sourcing forest products is receiving a big boost from research in remote sensing (e.g. radar detection of land cover change) and genetic analyses.  Individuals as well as buyers for corporate supply chains are increasingly attentive to sourcing issues and now have better leverage to identify products associated with recent deforestation.

3.  Carbon taxes.  Economists have long argued that the fastest and more practical strategy for driving down anthropogenic carbon emissions is to establish taxes on fossil fuel carbon emissions.  That approach of course tends to arouse political opposition, but several case studies prove carbon taxation is possible and effective.  The province of British Columbia in Canada imposed a moderate tax on fossil fuel emission in 2008, which has reduced fuel emissions on the order of 5-15%.  Sweden has one of the oldest and highest taxes on fossil fuel emissions.  Again, follow-up studies suggest emissions have declined, while maintaining solid GPD growth.  Various strategies have been employed to insulate the most vulnerable energy consumers from price increases.

4.  Satellite-based Monitoring of Methane Leakage.  Methane is a strong greenhouse gas in its own right and is eventually oxidized in the atmosphere to CO2.  Unfortunately, methane emissions are on the rise in recent years, with leakage from expanding coal and natural gas mining and infrastructure a significant factor.  Because methane has a relatively short atmospheric lifetime (about 8 years) compared to carbon dioxide, a decrease in methane emissions would have an especially large influence on global warming in the next few decades.  Earth system scientists use satellite borne sensors to track atmospheric methane concentrations and infer regional patterns in methane emissions.  But a new generation of sensors, including one run by the Environmental Defense Fund, is transforming the attribution of leakage sources by increasing the spatial and temporal resolution of the coverage.  These sensors will contribute to monitoring the effectiveness of the Global Methane Pledge recently signed at COP26.

The world is at, or fast approaching, the year of peak carbon dioxide emissions.  The signs of madness identified here serve to push that year farther into the future.  The signs of hope will hasten its arrival and help sustain a multidecadal trajectory towards net zero emissions.