1

Ecological Limits

Aliyu, Shamsuddeen Sheikh , Seriki, Eneye Ege

Department of Architecture, Faculty of Environmental Science,

Ahmadu Bello University, Zaria, Kaduna state.

Abstract

Finitude is an attribute that matter can be associated with. All

living things and non-living things are made up of matter,

consequently they have limits. These limits could be in terms of

lifespan, life style, tolerance and development (quantitatively and

qualitatively). These limits pose a serious challenge in the

sustainability of these living and non-living things. The

interrelationship between these living things (flora and fauna) and

the non-living environment is referred to as the ecosystem. The

sustainable relationship between them is termed ecological

balance. Once this balance has been attained, the system has a

limit to which it can tolerate disturbances or external forces acting

against this balance before it breaks down or transforms. This is

evident considering global issues/transformations such as global

warming, ozone layer rapture and their likes. This study looks at

these limits, the external forces/pressure acting against its balance

such as greenhouse emissions; deforestation etc. , causes of these

forces or disturbances such as industrialization, buildings etc.,

consequences of its collapse or transformation(both short and long

term) such as reduction in biodiversity, global warming, ozone

layer depletion etc. and possible remedial measures to damages

such as the ecological approach; the ecological economic

approach etc. as well as preventive actions such as policy

formulation etc. to those damages yet to be made.

Keywords: ecosystem; ecological Balance; Sustainability; ecological limits

Introduction

THE EARTH can provide only so many acres of forest, inches of topsoil, gallons of fresh

water and tones of metals. The coal and oil in the ground are non-renewable, and there is a

limit to the amount of pollution the atmosphere can absorb and clean. Natural resources and

services from ecosystems form the very basis of our global economy and their value is

2

thought to exceed the entire world‟s GDP. They are also, indisputably, finite. Similarly,

environmental limit is usually interpreted as the point or range of conditions beyond which

there is a significant risk of abrupt irreversible, or difficult to reverse, changes to these

benefits derived from natural resource systems with impacts on human well-being. If the

goals of sustainable development are to be achieved then we need to understand

environmental limits and thresholds. This study shall review current scientific thinking on

these topics. On the other hand, Natural resource systems as earlier stated provide a range of

benefits to people. These include clean and regular water supply, the production of food and

fiber, and the protection of communities from hazards. External pressures, such as pollution

or over-use, may impact upon natural resource systems and diminish the level or quality of

the benefits that they provide. Eventually people may judge that a critical point has been

reached, and that the reduction in benefit is no longer acceptable or tolerable. Such a critical

level can again best be described as an environmental limit. An important goal of

sustainable development is to maintain natural resource systems above such limits. Natural

resource systems can respond to increasing external pressures in various ways. Some systems

show a gradual decline in the level or quality or benefits they provide. Others show a more

rapid change or even exhibit sudden collapse. When a natural resource system exhibits a

rapid „regime shift‟, then this may be evidence of the existence of an environmental

threshold, marking the boundary between alternative stable states. This study shall look into

the factors and problems associated with ecological limits and their relationships in the

architectural point of view.

Definition of terms

Ecology is the scientific study of the relationships that living organisms have with each other

and with their natural environment. Topics of interest to ecologists include the composition,

distribution, amount (biomass), number, and changing states of organisms within and among

ecosystems. Ecosystems are composed of dynamically interacting parts including organisms,

the communities they make up, and the non-living components of their environment.

Biodiversity is the degree of variation of life forms within a given species, ecosystem,

biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity

is in part a function of climate. In terrestrial habitats, tropical regions are typically rich

whereas polar regions support fewer species. Rapid environmental changes typically cause

mass extinctions.

Climate change Global warming is also considered to be a major threat to global

biodiversity. For example coral reefs -which are biodiversity hotspots-, will be lost in 20 to

40 years if global warming continues at the current trend. In 2004, an international

3

collaborative study on four continents estimated that 10 percent of species would become

extinct by 2050 because of global warming. "We need to limit climate change or we wind up

with a lot of species in trouble, possibly extinct," said Dr. Lee Hannah, a co-author of the

paper and chief climate change biologist at the Center for Applied Biodiversity Science at

Conservation International

Thresholds are abrupt non-linear shifts in ecosystem states, affecting the capacity of the

ecosystem to sustain the delivery of ecosystem service benefits. These typically result from a

combination of gradual alterations in drivers, such as land use change, that appear to have

little or no apparent impact up to a certain point, until an external shock such as storm, fire or

disease outbreak causes the ecosystem to shift from one set of mutually reinforcing

ecological processes to another.

Environmental limits are established on the basis of the minimal acceptable output of

benefits or the societal choice for the level of risk of crossing a threshold such as the

Copenhagen Accord to limit temperature rise due to climate change to two degrees Celsius

above pre-industrial levels.

Environmental standards are generally used on a precautionary basis to inform target

setting for environmental policies, such as reductions in levels of pollutants that affect human

health. They include not only numerical and legally enforceable standards, but ones that are

not mandatory but contained in guidelines, codes of practice or sets of criteria for deciding

individual cases. They are judgments about the acceptability of environmental modifications

resulting from human activities

Figure 1: The Relationship between Targets, Standards and Environmental Limits.

4

Ecological limits

Robert Goodland in an article „Toward A Sustainable World Order’ Originally published in

Fall 1993 on page 12, summarized some of the most compelling evidence of ecological limits

as follows:

Human Biomass Appropriation: The best evidence that there are imminent limits is the

calculation by Peter Vitousek et al. that the human economy today uses – directly or

indirectly – about 40% of the net primary product of terrestrial photosynthesis. (This figure

drops to 25% if the oceans and other aquatic ecosystems are included.) After only a single

doubling of the world‟s population (perhaps, in 35 years) we will use 80% and 100% shortly

thereafter.

Global Warming: Scientists now practically universally agree that global warming will

occur, although differences remain on the rates. Greenhouse warming is a compelling

argument that ecological limits have been exceeded because it is globally pervasive, rather

than disrupting the atmosphere only in the regions where the CO2 was produced. The nearly 7

billion tons of carbon released into the atmosphere each year by human activity (from fossil

fuel consumption and deforestation) accumulate in the atmosphere, which suggests that the

ecosystem‟s sinks capable of absorbing carbon have been exceeded, and carbon accumulation

appears for all practical purposes irreversible on any relevant time frame.

Ozone Shield Rupture: Although 85% of CFCs are released in the industrial North, the main

ozone hole has appeared over Antarctica, showing the damage to be widespread and truly

global. The global ozone layer is thinning far faster than models had predicted. A second hole

has been discovered over the Arctic, and ozone-shield thinning recently was detected over

both north and south temperate latitudes, including northern Europe and North America.

Even if CFC emissions cease today, the world still will be gripped in an unavoidable

commitment to 10 years of increased damage. This would then gradually return to pre-

damage levels over the next 100 to 150 years.

Land Degradation: Land degradation – decreased productivity such as caused by

accelerated soil erosion, salination, and desertification – is not new; land degraded thousands

of years ago (for example, in the Tigris-Euphrates Valley) remains unproductive today. But

the scale has mushroomed. Pimentel et al. found that soil erosion is serious in most of the

world‟s agricultural areas and that this problem is worsening as more marginal land is

brought into production. Soil loss rates, generally ranging from 10 to 100 tons per hectare per

5

year, exceed soil formation rates by at least tenfold. Today‟s agricultural practices are leading

to erosion, salination, or waterlogging of possibly 6 million hectares per year. As a result of

widespread deficiencies in fuel wood, crop residues and dung are being diverted from

agriculture to fuel. This diversion coupled with fuel wood overharvesting intensifies land

degradation, hunger, and poverty. As 35 percent of the Earth‟s land already is degraded, and

because this figure is increasing and is largely irreversible in any time scale of concern to

society, such degradation is a sign that we have exceeded the regenerative capacity of the

Earth‟s soil source.

Decrease in Biodiversity: The scale of the human economy has grown so large that there is

no longer room for all species in the ark. The rates of takeover of wildlife habitat and of

species extinctions are the fastest they have been in recorded history and are accelerating.

The world‟s richest species habitat, tropical forest, has already been 55 percent destroyed; the

current rate exceeds 168,000 square kilometers per year.

Conservative estimates put the rate of extinction at more than 5,000 species each year. This

is about 10,000 times as fast as pre-human extinction rates. Less conservative estimates put

the rate at 150,000 species per year.

Ecological limits as it relate to Architecture

The Royal Architectural Institute of Canada in its bulletin titled “Architecture and climate

change, 2030 challenge” stated that Buildings and their construction consume more energy

than the transportation sector. The design, construction and operation of buildings are the

main sources of demand for energy and materials – both produce greenhouse gases

Source: Royal Architectural Institute of Canada

It further stated that “Greenhouse gas emissions from buildings are increasing dramatically”

backing up the statement with the fact that There is more than $30 billion worth of building

6

construction "on the drawing boards" in Architects' offices as of January 2007 and these

buildings will have a lifespan of at least50 to 100 years. These very buildings that are in the

design stages will consume energy and produce greenhouse gases. These more than 500,000

new buildings will not only consume electricity from central power plants, but they will also

burn fuel oil, natural gas or liquid propane in boilers, furnaces and hot water heaters. Most of

Canada‟s future energy requirements are required to operate buildings.

U.S. CO2 Emissions by Sector Source: American institute of Architects

Similarly, the American institute of Architects also asserted that Buildings Account For Half

of All Greenhouse Gas Emissions U.S. annual energy consumption is projected to increase by

37% (34 quadrillion Btu) and greenhouse gas emissions by 36% over the next twenty years.

Annual global energy consumption is projected to increase by 54% (230 quadrillion Btu)

over this same period.

In the same perspective, a recent report from the United Nations Intergovernmental Panel on

Climate Change (IPCC) states that “warming of the climate system is unequivocal.”

According to the IPCC, average global temperatures are increasing at an alarming rate. In just

the past 50 years, northern hemisphere temperatures were higher than during any other 50-

year period in the last 500 years, perhaps even the past 1,300 years. The IPCC projects that

the Earth‟s surface temperature could rise by as much as 4°C within the next century. The

primary cause of climate change is increasing concentration of greenhouse gases (GHGs),

especially carbon dioxide (CO2) in the atmosphere. The 2007 Assessment Report by the

IPCC indicates that GHG emissions increased by 70 percent between 1970 and 2004. These

gases are primarily emitted as a result of human behavior, such as the burning of fossil fuels

to produce energy. Building construction and energy use account for more than 30 percent of

worldwide emissions, while the transportation sector is responsible for another 30 percent.

7

Experts predict that the increase in the Earth‟s temperature, if left unchecked, will have

devastating effects. According to the IPCC, the projected sea level rise could reach 19-23

inches by the year 2100. Additional impacts could include:

Increased spread of diseases

Extensive species extinction

Drought and wildfires

Mass human, animal and plant migrations

Resource wars over shrinking amounts of potable water

Possible Remedial and Preventive Actions.

Several concerned bodies, organizations, institutions, scholars, both nationally and

internationally have been suggesting several preventive and remedial approach to this global

issue of concern with the aim of creating a sustainable environment. Some of these

approaches include the ecological economic, the ecological, the environmental economic, the

precautious approaches and their likes.

Comparison of these Principles

Ecological economic approach (I) (Goodland and Daly, 1996)

1. Maintenance of per capita manufactured capital (e.g. artefacts, infrastructure).

2. Maintenance of per capita renewable natural capital (e.g. healthy air, soils, natural forest).

3. Maintenance of per capita non-renewable substitutable natural capital (at present values, to

account for increasing scarcity).

4. Maintenance of non-substitutable, non-renewable natural resources (e.g. waste absorption

by environmental sinks such as rivers, oceans etc. Zero deterioration implies no net increase

in waste emissions beyond absorptive capacity

Ecological economic approach (II) (Holdren et al, 1992)

1. Limit levels of harm to those that are tolerable on a consistent basis (i.e. levels that are

non-cumulative) in return for the benefits of the activity that causes the harm.

2. Limit the degradation of monitorable environmental stocks of “essential” resources only, to

not more than 10% per century, to give societies the time to develop substitutes and alter

related systems.

Ecological economic approach (III) (Weterings and Opschoor, 1992)

1. No exhaustion of renewable resources, and residual stocks of non-renewables sufficient for

50 years' use.

8

2. No accumulation of pollution or lasting effects for future generations.

3. Encroachment relates to interventions that affect natural structures and systems. Loss of

acreage must not exceed the area added or restored by natural or artificial means.

Environmental economic approach (I) (Jacobs, 1991)

1. For renewable resources harvest or use rate should not exceed the regeneration rate

2. For non-renewable resources, maintenance of the stock level relative to demand.

3. For waste assimilation capacity, sustainability is maintained when the rate and

concentration of non-persistent waste discharges remain within the assimilative capacity of

the environmental medium.

4. For life support services maintenance of a set of “life support indicators”

Environmental economic approach (II) (Ekins, 1994; 1996)

1. Destabilization of global environmental features must be prevented, by maintaining

biodiversity, preventing of climate change and protecting the ozone layer.

2. Important ecosystems and ecological features must be absolutely protected to maintain the

functional biological diversity that underpins the productivity and resilience of ecosystems.

3. The renewal of renewable resources must be ensured by maintaining soil fertility, hydro-

biological cycles and necessary vegetative cover, and by the rigorous enforcement of

sustainable harvesting.

4. Depletion of non-renewable resources should balance the maintenance of a minimum life

expectancy for the resource with the development of substitutes for it.

5. Emissions into air, soil and water must not exceed critical load, that is the capability of the

receiving media to disperse, absorb, neutralize and recycle them, nor may they lead to life-

damaging concentrations of toxins.

6. Risks of life-damaging events from human activity must be kept at low levels.

Technologies with high damage potential, even if low risk, should be foregone.

An ecological approach (Moser and Narodoslawsky, 1993)

1. Anthropogenic material fluxes must not exceed the local assimilation capacity of natural

cycles, and should be smaller than natural perturbations in material flows.

2. Anthropogenic material flows must not alter the content and quality of natural storage

systems, such as aquifers and fossil raw material deposits.

3. Renewable resources must only be extracted at a rate not exceeding local fertility.

4. The natural variety of species and landscapes must be sustained and improved.

9

A precautious approach (Upham, 1999 and 2001, after Holmberg, 1995 and Holmberg

et al. 1996)

1. Conceptual research and sectorial negotiation is needed to establish emissions and

consumption quotas, with supporting fiscal or other regulatory incentives, to bring the human

economy within the critical levels of large-scale environmental systems.

2. Indicating sustainability requires absolute measures of material input and waste outputs to

air, water and land, as well as the same relative to business or economy performance. Waste

output means all unwanted emissions to air, water and land. Non-waste output (products) will

consist of input material less waste output material.

3. Substitution of biologically-derived materials for mined and some synthetic materials, and

increased use of this bio material, may be desirable if the material can be biodegraded, is

grown on degraded land, or otherwise has a lower impact than the mined or synthetic

materials. Consumption targets, quotas and indicators should reflect this.

Conclusion

The discussion of ecological limits seems to have taken us to the boundaries of what

traditional science has been expected to provide. The current rate at which the natural

resources or capital are exhausted is alarming considering the finitude of these resources,

which ultimately gives it a limit to which these resources can be tapped. In many of the areas

reviewed, for example, scientists acknowledge that, while their work can map out what

consequences might follow if certain limits are crossed, the significance of limits has to be

determined by society at large. Buildings contribute a lot to the greenhouse effect, as such

architects have a lot to contribute to the conservation of the environment. The most important

fact that has to understood is that all actions must be done while there is still the chance to do

so.

10

Refrences

D. Pimentel, et al. "World Agriculture and Soil Erosion." BioScience 37(4) 1987.

Ekins, P. (1994): The environmental sustainability of economic processes: a

framework for analysis. In: van den Bergh, J. and van der Straaten, J. (Eds.)

Toward Sustainable Development: concepts, methods and policy, Island Press,

Washington, DC: 25-55.

Folke, C., Holling, C.S. and Perrings, C. (1996) “Biological Diversity,

Ecosystems, and The Human Scale”, Ecological Applications, 6 (4), pp.1018-1024.

Goodland, R. and Daly, H. (1996) "Environmental Sustainability: Universal and Non-

Negotiable", Ecological Applications, 6(4), pp.1002-1017.

Haines-Young, R, Potschin, M, Cheshire, D, 2006, Defining and Identifying Environmental

Limits for Sustainable Development. Final Report. Defra Project Code NR0102

Holdren, J. P., Daily, G. C. and Ehrlich, P. R. (1992): The Meaning of Sustainability:

Biogeophysical Aspects. Paper presented at the International Conference on the

Definition and Measurement of Sustainability, Biophysical Foundation, 22-25

June, Washington D.C.

Jacobs, M. (1991): The Green Economy: environment, sustainable development and

the politics of the future. Pluto Press, London.

IPCC SAR WGI op.cit. Summary for Policy Makers, p. 6

IPCC SAR WGII op.cit. Summary for Policy Makers, p. 9

Moser, A. and Narodoslawsky, M. (1993): Ecological Bioprocessing - Task Group of

European Federation of Biotechnology 1990-1993 - Final Report, ÖGBPT,

Graz, Austria.

Peter Vitousek, et al. "Human Appropriation of the Products of Photosynthesis." BioScience

34(6) 1986.

Upham, P. (1999): An Assessment of The Natural Step as a Framework for Technology

Choice. Unpublished PhD thesis, PREST (Policy Research in Engineering, Science and

Technology), University of Manchester.

Weterings, R. A. P. M. and Opschoor, J. B. (1992): The Ecocapacity As A Challenge

To Technological Development. Advisory Council for Research on Nature and

Environment, publication RMNO nr. 74a, Rijswijk, April 1992.