Resources, Waste, and Sustainability
1. Natural Resources
Learning outcomes
Natural Resources
Natural resources are materials, substances, organisms, and forms of energy that occur in nature and are used by humans.
They provide many of the things societies depend on, including:
- food
- freshwater
- energy
- building materials
- metals
- fuels
- medicines
- clothing materials
- industrial raw materials
Examples include forests, soil, water, minerals, sunlight, wind, fish, coal, oil, and natural gas.
Natural resources are not unlimited. Sustainable resource management aims to meet human needs while protecting the natural systems needed by future generations.
Renewable and Non-Renewable Resources
Natural resources are often classified as either:
renewable
or
non-renewable
The distinction depends largely on how quickly the resource can be replaced compared with how quickly humans use it.
Renewable Resources
A renewable resource can be naturally replenished on a timescale that can support continued human use, provided it is managed appropriately.
Examples include:
- sunlight
- wind
- flowing water
- forests
- fish populations
- biomass
However, renewable does not mean unlimited.
A renewable biological resource can still be depleted if humans use it faster than it can recover.
Non-Renewable Resources
A non-renewable resource exists in a limited supply or forms so slowly that it cannot be replaced on a useful human timescale.
Examples include:
- coal
- oil
- natural gas
- metal ores
- many mineral deposits
Once these materials are extracted and used, the original geological deposit is not quickly replaced.
For example, fossil fuels formed through geological processes occurring over millions of years.
Therefore:
human consumption rate >> natural replacement rate
Comparing Renewable and Non-Renewable Resources
The classification does not automatically tell us whether using the resource has environmental impacts.
Both renewable and non-renewable resources must be managed carefully.
Renewable Does Not Mean Sustainable
Consider a forest.
Trees can regrow, so forests are renewable.
However:
trees removed faster than forest regrowth → forest area decreases
Similarly:
fish harvested faster than reproduction → fish population decreases
A renewable resource is sustainable only when its rate of use is compatible with its rate of replenishment.
A useful relationship is:
rate of use ≤ rate of renewal
over the long term.
Major Natural Resources
Human societies depend on many types of natural resources.
Important categories include:
Water resources
- rivers
- lakes
- groundwater
- rainfall
Biological resources
- forests
- crops
- livestock
- fish
- wildlife
Geological resources
- metals
- minerals
- rocks
- fossil fuels
Energy resources
- coal
- oil
- natural gas
- sunlight
- wind
- moving water
- geothermal energy
Land and soil
- agricultural soil
- grazing land
- forests
- land for settlements and infrastructure
These resources are often interconnected.
Freshwater
Freshwater is essential for:
- drinking
- sanitation
- agriculture
- industry
- electricity generation
- ecosystems
Water moves continuously through the water cycle, making freshwater a renewable resource.
However, usable freshwater can still become scarce because of:
- overuse
- groundwater depletion
- drought
- pollution
- uneven geographic distribution
Therefore, renewable water supplies can still be used unsustainably.
Groundwater
Groundwater is stored underground in soil and rock.
Underground formations capable of storing and transmitting useful quantities of groundwater are called aquifers.
Groundwater can be replenished through recharge when water infiltrates into the ground.
Problems occur when:
groundwater extraction > groundwater recharge
for long periods.
Possible consequences include:
- falling water tables
- dry wells
- reduced river flow
- damage to wetlands
- land subsidence in some locations
Soil
Soil is an essential natural resource because it supports:
- agriculture
- forests
- grasslands
- nutrient cycling
- water storage
- terrestrial ecosystems
Although soil can form naturally, soil formation is usually slow.
Loss of fertile topsoil through erosion can occur much faster than new soil forms.
So soil is often considered renewable only if carefully managed.
Soil Depletion
Soil can be degraded through:
- erosion
- nutrient depletion
- compaction
- salinization
- contamination
- loss of organic matter
Degraded soil may become less productive.
This creates an important connection:
resource degradation → lower agricultural productivity → greater pressure on remaining productive land
Protecting soil is therefore an important form of natural-resource management.
Forests
Forests provide resources including:
- timber
- paper
- fuelwood
- food
- medicines
They also provide ecosystem services such as:
- carbon storage
- water regulation
- erosion control
- wildlife habitat
- nutrient cycling
Forests can be renewable when harvesting does not exceed their capacity to recover.
Deforestation
Deforestation is the large-scale removal of forest.
Forests may be cleared for:
- agriculture
- timber
- roads
- mining
- settlements
- infrastructure
Possible consequences include:
- habitat loss
- biodiversity decline
- soil erosion
- altered water cycles
- release of stored carbon
- reduced carbon uptake
Resource use can therefore affect many parts of an ecosystem.
Sustainable Forestry
Sustainable forestry attempts to obtain forest products while maintaining forest ecosystems.
Strategies can include:
- controlled harvesting
- replanting
- protecting sensitive areas
- maintaining habitat
- reducing soil damage
- preventing illegal logging
- monitoring forest recovery
The goal is not necessarily to prevent all harvesting.
Instead:
harvest ≤ long-term forest recovery
while important ecosystem functions are maintained.
Fisheries
Fish populations are renewable biological resources because fish reproduce.
However, fisheries can become depleted if:
harvest rate > reproduction and population recovery
This is called overfishing.
Overfishing can:
- reduce fish populations
- disrupt food webs
- reduce future catches
- damage fishing communities economically
Sustainable Fisheries
Strategies for managing fisheries may include:
- catch limits
- size limits
- seasonal restrictions
- protected areas
- restrictions on fishing equipment
- monitoring fish populations
Scientists can collect data about:
- population size
- reproduction
- age distribution
- catch rates
Management decisions can then be adjusted using evidence.
Fossil Fuels
The major fossil fuels are:
- coal
- oil
- natural gas
They contain chemical energy originally derived from ancient biological material.
Fossil fuels are non-renewable because their formation requires geological timescales.
Humans use them for:
- electricity
- transportation
- heating
- industrial processes
- chemical manufacturing
Problems Associated with Fossil Fuels
Fossil fuel extraction and use can cause:
- habitat disturbance
- air pollution
- greenhouse gas emissions
- water contamination
- oil spills
- land degradation
Combustion releases carbon dioxide:
fuel + oxygen → carbon dioxide + water + energy
The transfer of geological carbon into the atmosphere contributes to changes in Earth's carbon cycle.
Mineral Resources
Modern societies use many mineral resources.
Examples include:
- iron
- copper
- aluminum ores
- lithium
- nickel
- phosphate rock
- rare-earth elements
These materials are used in:
- buildings
- vehicles
- electronics
- batteries
- electrical wiring
- fertilizers
- renewable-energy technologies
Most mineral deposits are non-renewable on human timescales.
Mining
Mining removes useful geological materials from Earth.
Mining can provide essential resources but may also cause:
- habitat destruction
- soil disturbance
- erosion
- large quantities of waste rock
- water pollution
- dust
- high energy consumption
Mining impacts depend strongly on:
- mining method
- location
- mineral being extracted
- environmental management
- restoration after mining
Ore Grade
An ore is rock containing enough of a useful material to make extraction practical under particular economic and technological conditions.
Some ores contain relatively high concentrations of the desired material.
As richer deposits become depleted, mining may shift toward lower-grade ores.
Lower-grade ores may require:
- moving more rock
- using more energy
- producing more waste
to obtain the same amount of useful material.
Resource depletion therefore does not always mean that an element completely disappears.
It may mean that obtaining it becomes increasingly difficult or expensive.
Resource Depletion
Resource depletion occurs when a resource is used faster than it can be replaced or when accessible reserves decline substantially.
For renewable resources:
use > renewal → depletion
For non-renewable resources:
continued extraction → remaining stock decreases
Depletion can create:
- shortages
- increased costs
- environmental pressure
- economic problems
- competition between users
Resource Scarcity
Resource scarcity occurs when the available supply of a resource is insufficient to meet demand under existing conditions.
Scarcity may result from:
- physical shortage
- high demand
- pollution
- unequal distribution
- limited infrastructure
- economic barriers
A resource can therefore exist physically but still be inaccessible to some people.
Why Resource Management Matters
Resource management involves planning how resources are:
- extracted
- used
- protected
- recycled
- restored
Good management aims to prevent short-term benefits from creating larger long-term problems.
For example:
poor forest management
may produce timber quickly but damage future timber supplies.
poor groundwater management
may increase irrigation today but reduce water availability later.
Sustainable management considers both present and future needs.
The Tragedy of the Commons
Some resources are shared by many users.
Examples include:
- oceans
- fisheries
- rivers
- groundwater
- the atmosphere
If each user attempts to maximize personal benefit, the shared resource may become depleted or degraded.
This situation is sometimes called the tragedy of the commons.
For example:
each fishing boat catches as much as possible
↓
total harvest becomes too large
↓
fish population declines
↓
eventually everyone has fewer fish
Cooperative management can help prevent this problem.
Sustainable Resource Use
Sustainable resource use means using resources at rates and in ways that can be maintained over the long term without causing unacceptable environmental or social damage.
For renewable resources, this often involves:
rate of use ≤ rate of regeneration
For non-renewable resources, sustainability may involve:
- reducing unnecessary consumption
- increasing efficiency
- recycling
- reusing materials
- developing substitutes
- transitioning toward renewable alternatives
Resource Efficiency
Resource efficiency means obtaining more useful output from a given quantity of resources.
For example, suppose two factories produce the same number of products.
Factory A uses:
100 tonnes of raw material
Factory B uses:
75 tonnes
If product quality is equal, Factory B has greater material efficiency.
Improving efficiency can reduce:
- resource extraction
- waste
- energy use
- costs
Reduce, Reuse, Recycle
One familiar resource-management strategy is:
REDUCE → REUSE → RECYCLE
Reduce
Use fewer resources in the first place.
Reuse
Use products or components again.
Recycle
Process materials so they can become raw materials for new products.
These strategies can reduce demand for new resource extraction.
Why Reduce Comes First
Recycling requires:
- collection
- transportation
- sorting
- processing
- energy
Avoiding unnecessary resource use can therefore be even more effective.
For example:
unnecessary product never manufactured
means fewer resources may be needed for:
- extraction
- manufacturing
- transportation
- disposal
Reducing consumption addresses the problem earlier in the resource chain.
Reusing Resources
Products can sometimes be:
- repaired
- refurbished
- shared
- resold
- repurposed
Extending a product's useful life reduces the need to manufacture replacements.
For example, repairing an electronic device may delay the need for additional:
- metals
- plastics
- energy
- transportation
Recycling Metals
Metals are particularly valuable candidates for recycling.
Unlike fossil fuels, metals are not destroyed simply by being used.
For example, copper from:
- electrical wiring
- electronics
- machinery
can potentially be recovered and used again.
Recycling metals can reduce the need for new mining.
Recycling and Energy
Producing materials from recycled sources can sometimes require less energy than extracting and processing new raw materials.
For example, recycling certain metals can avoid energy-intensive stages of:
- mining
- crushing
- concentrating
- refining
However, recycling still has environmental costs.
The best strategy often combines:
reduced consumption + reuse + recycling
The Circular Economy
A traditional production system is often described as:
TAKE → MAKE → USE → DISPOSE
This is a linear economy.
A circular economy aims to keep materials in use for longer.
A simplified model is:
DESIGN → MAKE → USE → REPAIR → REUSE → RECYCLE → MAKE AGAIN
The goal is to reduce both resource extraction and waste.
Product Design and Resources
Resource conservation can begin when products are designed.
Products can be designed to:
- last longer
- be repaired
- use fewer materials
- contain recycled materials
- be easily disassembled
- have recyclable components
Poor design can make valuable materials difficult to recover.
Good design can keep resources circulating through the economy.
Renewable Energy Resources
Renewable energy resources include:
- sunlight
- wind
- flowing water
- geothermal energy
- some forms of biomass
These resources can reduce dependence on fossil fuels.
However, renewable energy technologies still require:
- land
- materials
- infrastructure
- metals
- manufacturing
Therefore:
renewable energy ≠ zero environmental impact
Sustainability requires evaluating the complete system.
Solar Energy
Solar energy uses radiation from the Sun.
Advantages include:
- renewable energy supply
- no fuel combustion during electricity generation
- low operational greenhouse gas emissions
Challenges include:
- variable sunlight
- energy storage
- land requirements in some projects
- materials needed for equipment
Wind Energy
Wind turbines convert kinetic energy in moving air into electrical energy.
Advantages include:
- renewable energy
- no fuel combustion during operation
- relatively low operational emissions
Possible challenges include:
- variable wind
- visual impacts
- wildlife interactions
- suitable site availability
Hydroelectric Power
Hydroelectric systems use moving or falling water.
Advantages can include:
- renewable electricity
- reliable generation in suitable locations
- potential energy storage in some reservoir systems
Possible impacts include:
- flooding land
- changing river ecosystems
- blocking fish movement
- changing sediment transport
Again, renewable does not mean impact-free.
Biomass
Biomass is biological material that can be used as an energy source.
Examples include:
- wood
- crop residues
- some organic wastes
Biomass may be renewable if harvesting does not exceed regrowth.
However:
biomass harvested faster than regrowth → unsustainable resource use
Land use and emissions must also be considered.
Evaluating Resource Sustainability
A resource should not be judged using only the labels "renewable" or "non-renewable."
Useful questions include:
Availability
How much of the resource exists?
Renewal rate
How quickly is it replaced?
Consumption rate
How quickly are humans using it?
Environmental impact
What happens during extraction and use?
Waste
How much material is discarded?
Recyclability
Can the resource be recovered?
Energy use
How much energy is required?
Ecosystem effects
Does resource use damage habitats or biodiversity?
Social effects
Who receives the benefits and who experiences the costs?
Life-Cycle Thinking
To evaluate resource use properly, scientists can examine the entire life cycle of a product.
A simplified life cycle is:
RAW MATERIAL → EXTRACTION → MANUFACTURING → TRANSPORT → USE → END OF LIFE
Environmental impacts can occur at every stage.
For example, an electric device may produce no direct emissions during use but still require:
- mined metals
- manufacturing energy
- transportation
- eventual recycling or disposal
A complete evaluation considers all these stages.
Ecological Footprint
An ecological footprint is one way of thinking about the environmental resources required to support human activities.
Human lifestyles require resources for:
- food
- housing
- transportation
- electricity
- manufactured products
Different lifestyles can therefore place very different demands on Earth's resources.
Reducing unnecessary resource consumption can reduce environmental pressure.
Population and Resource Demand
Resource demand is influenced by both:
- population
- consumption per person
A simplified relationship is:
total resource demand ≈ population × resource use per person
A growing population can increase demand.
However, high consumption per person can also produce very large resource demands.
Resource management therefore involves both technological efficiency and consumption patterns.
Technology and Resource Availability
Technology can change which resources are economically useful.
For example, improved technology can:
- increase recycling
- reduce material requirements
- extract resources more efficiently
- make renewable energy cheaper
- allow lower-grade deposits to be used
However, increased efficiency does not automatically eliminate resource depletion.
If total consumption continues increasing rapidly, resource demand can still rise.
Substitution
When one resource becomes scarce or environmentally damaging, another material may sometimes replace it.
This is called substitution.
For example:
- renewable electricity can replace some fossil fuel use
- recycled metals can replace some newly mined metals
- alternative materials can replace scarce resources
However, substitutes may have environmental impacts of their own.
The complete system should still be evaluated.
Example: Is Timber Sustainable?
Timber comes from trees, so it is renewable.
But consider two forests.
Forest A
Trees are harvested faster than they regrow.
Habitats are destroyed.
Soil erosion increases.
Forest B
Harvesting is controlled.
Young trees regenerate.
Sensitive habitats are protected.
Soil damage is minimized.
Both use a renewable resource.
However, Forest B represents the more sustainable system.
The important question is not simply:
"Is it renewable?"
but:
"How is it managed?"
Example: Is Solar Power Sustainable?
Sunlight is renewable.
However, solar panels require materials including:
- glass
- metals
- semiconductor materials
Their manufacture requires energy and resources.
A good evaluation therefore considers:
renewable energy produced
against:
materials + manufacturing + land use + disposal/recycling
Solar power can still provide major sustainability benefits, but the evaluation should consider its entire life cycle.
Example: Managing a Fishery
Suppose a fish population can sustainably replace approximately:
50,000 fish per year
but fishing removes:
80,000 fish per year
Net population change:
50,000 − 80,000 = −30,000 fish per year
If this continues, the population will decline.
Reducing the catch to below the population's sustainable replacement rate could allow the resource to recover.
Example: Groundwater Use
An aquifer receives approximately:
10 million m³/year
of recharge.
Humans pump:
15 million m³/year
Difference:
10 − 15 = −5 million m³/year
The groundwater store is declining by approximately:
5 million m³/year
under this simplified model.
Even though groundwater can be renewable, this rate of use is not sustainable.
Resource Management and Future Generations
Sustainability includes the idea that today's decisions affect future people.
If one generation:
- exhausts high-quality mineral deposits
- destroys fertile soil
- depletes groundwater
- eliminates fish populations
- removes forests
future generations inherit fewer options.
Sustainable management therefore asks:
How can we meet present needs without unnecessarily reducing future opportunities?
Common Mistakes
Thinking Renewable Means Unlimited
Renewable resources can still be depleted when use exceeds regeneration.
Thinking Non-Renewable Means It Will Suddenly Disappear
Depletion often means resources become:
- harder to obtain
- more expensive
- lower quality
before they are completely exhausted.
Assuming Renewable Resources Have No Environmental Impacts
Hydroelectric dams, wind farms, solar facilities, and biomass systems can all affect environments.
Assuming Recycling Creates Unlimited Resources
Recycling involves losses, energy, collection, and processing.
Reducing and reusing resources remain important.
Thinking Water Is Always Sustainable Because of the Water Cycle
Local water supplies can be depleted or polluted faster than they recover.
Thinking Forests Are Automatically Sustainable
Forests are renewable only when harvesting and ecosystem damage remain within recoverable limits.
Confusing Resource Availability with Access
A resource may exist but still be inaccessible because of:
- location
- cost
- infrastructure
- technology
Evaluating Only the Use Stage
Resource impacts can occur during:
- extraction
- manufacturing
- transportation
- use
- disposal
Life-cycle thinking provides a more complete evaluation.
Key Terms
Natural resource — Material, organism, substance, or form of energy from nature that humans use.
Renewable resource — Resource that can naturally replenish on a timescale capable of supporting continued use if properly managed.
Non-renewable resource — Resource that exists in finite quantities or forms too slowly to replace on useful human timescales.
Resource depletion — Reduction in the available supply of a resource through use or degradation.
Resource scarcity — Situation in which available resource supply is insufficient to meet demand.
Resource management — Planning and controlling how natural resources are extracted, used, protected, and restored.
Sustainable resource use — Resource use that can be maintained over the long term without unacceptable environmental or social damage.
Aquifer — Underground rock or sediment capable of storing and transmitting groundwater.
Groundwater recharge — Addition of water to underground water stores.
Deforestation — Large-scale removal of forests.
Overfishing — Harvesting fish faster than populations can sustainably recover.
Fossil fuel — Non-renewable fuel such as coal, oil, or natural gas formed from ancient organic material.
Ore — Rock containing enough useful material to make extraction practical.
Resource efficiency — Obtaining greater useful output from a given quantity of resources.
Reuse — Using a product or component again rather than discarding it.
Recycling — Processing used materials so they can become raw materials for new products.
Circular economy — System designed to keep products and materials in use through durability, repair, reuse, and recycling.
Biomass — Biological material that can be used as a resource, including as an energy source.
Substitution — Replacing one resource or material with another.
Life cycle — All stages of a product from raw-material extraction through manufacture, use, and end-of-life management.
Ecological footprint — Measure or concept describing the environmental resources required to support human activities.
Key Takeaways
- Natural resources provide materials and energy required by human societies.
- Major resources include water, soil, forests, fisheries, minerals, fossil fuels, sunlight, and wind.
- Renewable resources can replenish naturally, but they are not necessarily unlimited.
- Non-renewable resources form too slowly to replace at the rate humans use them.
- A renewable resource becomes unsustainable when consumption exceeds regeneration.
- Groundwater can be depleted when pumping exceeds recharge.
- Soil can be degraded much faster than fertile topsoil forms.
- Forests and fisheries require management to remain renewable.
- Fossil fuels and most mineral deposits are non-renewable.
- Mining can provide essential materials while also creating environmental impacts.
- Resource depletion can make materials increasingly difficult or expensive to obtain.
- Sustainable management balances current resource use with future availability.
- Reducing consumption can prevent resource demand before waste is created.
- Reuse extends the useful life of products.
- Recycling reduces demand for some newly extracted raw materials.
- Circular systems aim to keep materials in use rather than continuously extracting and discarding them.
- Renewable energy reduces dependence on fossil fuels but still requires materials and infrastructure.
- Life-cycle thinking evaluates environmental impacts from extraction through disposal.
- Technology, recycling, efficiency, and substitution can reduce pressure on natural resources.
- Sustainability depends not only on what resource is used, but also how quickly, efficiently, and responsibly it is used.
A useful test for renewable resources is:
RATE OF USE ≤ RATE OF REPLENISHMENT
And a useful strategy for all resources is:
REDUCE → USE EFFICIENTLY → REUSE → REPAIR → RECYCLE → RECOVER
The central question is not simply:
"How much of this resource do we have?"
It is:
"How can we use this resource while preserving the ability of natural and human systems to function in the future?"