Freshwater sources drying up, reduction of fish stocks' populations, not enough land for ffood crops to sustain the human population. There are a limited number of resources on our planet. In order to sustain life on Earth, we need to understand the productivity of the world's ecosystems and the demands that human populations place on these ecosystems. Although Earth is seemingly doomed to the onslaught of human development and population expansion, biocapacity and ecological footprint values offer an evaluation of the current balance between environment and exploitation and show us what needs to be changed for a sustainable future.
In this article, we review the ecological footprint, its definition, the factors that affect ecological footprint with some examples, how to measure it, and the biocapacity and ecological footprint relationship.
Ecological Footprint Definition
The sum of the areas required for ecosystems to produce resources for human consumption is the ecological footprint.
Ecological footprint is measured by the area of productive land and water, that successfully provides for the number of resources a population consumes and, absorbs the amount of waste the population releases. Resources include:
- Livestock
- Water
- Building materials
- Plant-based food
- Fish
- Space for living
Fig. 1 Ecological footprint by country at year 2007. Developed countries (red dark) have a higher ecological footprint than developing countries (more purple ones).
Environmental sustainability describes the stable state of a population where the demand for resources matches the output by the productive land mass to which the population has access.
Ecological Footprint Example
You can imagine a population's ecological footprint as being their environmental bank account. The footprint will measure the demand of the population for resources and waste they release, and the supply of biologically productive land in terms of the provision of resources and absorption of waste. Here is a diagram that shows an example of a range of biologically productive land and human development:
Just as a bank statement tracks income against expenditures, Ecological Footprint accounting measures a population’s demand for natural ecosystems’ supply of resources and services.
On the demand side, the Ecological Footprint measures an individual or a population’s demand for plant-based food and fiber products, livestock and fish products, timber and other forest products, space for urban infrastructure, and forest to absorb its carbon dioxide emissions from fossil fuels.
On the supply side, a city, state, or nation’s biocapacity represents its biologically productive land and sea area, including forest lands, grazing lands, cropland, fishing grounds, and built-up land.
Ecological Footprint Factors and Examples
Let's have a look at the social and economic factors affecting ecological footprint, and some of the environmental implications of the choices we make.
Infrastructure
The buildings we choose to build as civilisations and the way we house ourselves have huge impacts on our ecological footprint. The demand for more materials will require the demolition of productive habitats and often the reduction of producer populations (deforestation of arboreal areas). Therefore, ecosystems providing other services will be affected and will be less able to absorb waste (carbon dioxide emissions). Clearing room for urban development is often at the expense of productive habitats as well.
Examples of productive habitats are ones that provide resources for human populations. For example, forests provide timber and rocky areas will contain metal ores and phosphate rocks.
Food and Water Consumption
Different populations will consume more resources than others. This is especially prevalent in developed countries where efficient agricultural practices and mass production roll out huge amounts of food every day. Compare this to under-developed countries (for example in Sub-Saharan Africa) where farmers struggle to produce enough food to meet the needs of villages where technology and land productivity are low.
An average American family consumes 552 gallons of water a day compared to 5 gallons by an African family, just to give an idea of the striking contrast between the developing and industrialised world.
Appropriate agriculture
Agroecosystems are included in the productive land, but inappropriate agricultural practices can reduce surrounding biodiversity and damage nearby aquatic ecosystems. Ill-informed application of pesticides can kill off insect populations that are staples of the surroundings and negatively impact their fellow species, competitors, and predators. Overuse of fertilisers can cause soils to become overconcentrated in nutrients, allowing the potential for leaching after rain and the eutrophication of nearby water bodies.
Eutrophication is the suffocation of oxygen from water sources. Nutrient overload causes algal blooms to form. When bacteria break these algal blooms down, they will use up the ecosystem's oxygen.
The presence of butterflies in agricultural ecosystems is a reliable bioindicator for many factors such as biodiversity and environmental stability, as well as recent anthropogenic habitat fragmentation and urbanisation. Butterflies depend on the presence of plants in their habitat. With a basic knowledge of butterfly-flora relationships in agricultural areas, butterfly populations are analogous to certain plant populations.
Energy
Although there have been promising advances in renewable energy sources in the last couple of decades, it is non-renewable sources which dominate energy production. Fossil fuels (gas, coal, and oil) are used in abundance in agriculture, mass production, transport, and electricity. These fossil fuels are not only non-renewable and are using up resources, but also release waste in the form of carbon dioxide and other dangerous by-products.
Coal contains sulphur, so the incomplete combustion of coal will release sulphur dioxide (SO2) into the atmosphere. Sulphur dioxide is extremely dangerous because it can react with atmospheric water vapour to form acid precipitation. SO2 can initiate free radicals in the stratosphere that deplete the ozone layer and allow more harmful ultraviolet radiation to the Earth's surface.
Domestic stoves that use coal or wood, release carbon monoxide, which is toxic, along with other harmful compounds.
Economic Arms Race
Most countries and civilisations are constantly competing to be the most powerful. Power normally comes with being the richest, producing the most energy, and having the largest cities. These endeavours do not always consider environmental implications and involve:
- Burning fossil fuels
- Intensive agricultural practices
- Clearing productive habitats for space
Environmental Degradation
These factors we have covered will have an impact on the environment the majority of the time. Mass production, energy, agriculture, transport, and heavy machinery involved in building infrastructure all release greenhouse gases. These GHGs contribute to the greenhouse effect and global warming. Global warming puts stress on many productive areas that we rely on for resources. Agriculture is becoming more difficult in warmer temperatures (especially in the tropics). Warmer environments also cause migration of species northward which has consequences for entire ecosystems and their productivity of resources.
An ecosystem is a complex web of interspecies relationships where different organisms depend on one another for survival. Predator-prey dynamic, competition, and symbioses are just some of these types of relationships.
The greenhouse effect involves greenhouse gases absorbing infrared radiation that has been reflected from the Earth's surface and re-emitting it back towards the surface, which warms the planet.
Ecological Footprint Measures
There are a variety of ways of measuring a person or population's ecological footprint when data is collected on their lifestyle and consumption. For example, simple measures of their meat consumption, water usage, recycling, type of energy used, and modes of transport can help to give a rough estimate. However, there are ways of being more accurate in footprint measures, but first, we need to get to grips with a global hectare.
Global hectares are units tha assess the biocapacity of the Earth. They describe the output of all biologically productive areas on the planet (this can include forests, fishing areas, and farms) in a given year.
Remember, barren unproductive areas like arid deserts and frozen tundra may contain vast ecosystems, but are not biologically productive or useful to human populations so are discounted in global hectares.
Here is an ecological footprint calculation which has been introduced in recent years.
EF = ΣTi/Yw x EQFi
The variables are as follows:
EF = Ecological Footprint in global hectares
T = tonnes consumed in a year by the population
i = product that is being investigated
Yw = average yield of the investigated product for the whole world
EQFi = the equivalence factor for the investigated product
Average yield takes into account different landscapes and productivities for the product over the whole planets, while equivalence factors convert the investigated area into a suitable number of global hectares.
Biocapacity Definition
The biocapacity of a specific area concerns the entirety of the available biologically productive land and water. This can include cropland, grazing land, fishing spots, arboreal areas, and land cleared for human development. A region possessing a large biocapacity will be able to support the demands of a larger population and higher consumption. Biocapacity is measured in global hectares too, so comparisons can be easily made with a population's ecological footprint.
Here are some important limits to realise when considering biocapacity:
The finite nature of the vast majority of resources we have access to and that we rely on.
The ever-expanding global population will demand more resources.
The ability of the environment to recover from human interference.
The majority of resources we consume (fossil fuels, fish, phosphate rocks) are finite, so switching to renewable alternatives is essential in guaranteeing a sustainable future.
Biocapacity and Ecological Footprint Relationship
Exploring the relationship between ecological footprint and biocapacity is important in understanding the steps that need to be taken in society to ensure the trajectory of our planet is sustainable. When comparing both values in global hectares, there are two terms we need to know.
An ecological surplus is a situation where the biologically productive land out-produces the resources and waste absorption required to support the population in the given area.
An ecological deficit is a situation where the demand for resources and waste released outweighs the productivity and absorption rate of the productive land mass.
Measurements of biocapacity and ecological footprint on global, regional, and local scales can help us to identify problem regions lacking in renewable resources and implement initiatives to reduce pressures on biocapacity in these areas. A global average biocapacity is a common goal to maintain a lower ecological footprint, but this may not always be realistic with the range of landscapes and conditions affecting productivity around the world.
Biocapacity and ecological footprint - Key takeaways
- Ecological footprint measures the size and productivity of the area needed to provide resources demanded by a population and absorb the waste they release.
- Many factors influence ecological footprint, these include land use, agriculture, energy usage, and consumption.
- Biocapacity is the biological productivity of a given region. Biologically productive areas include cropland, pastures, fishing regions, and land used for development.
- Comparing the relationship between the ecological footprint of a population and the biocapacity of the land mass they live in can tell us how sustainable their trajectory is.
- Our planet is currently in an ecological deficit, meaning the demand for resources far outweighs the supply of biologically productive land on Earth.
- To reduce, environmental degradation from emission, pollution, and exploitation, countries must reduce their ecological footprint (especially developed countries).
References
- Fig. 1 - World map of countries by ecological footprint (2007) (https://commons.wikimedia.org/wiki/File:World_map_of_countries_by_ecological_footprint_(2007).svg) by Jolly Janner, public domain.
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