Environmental Planning: Ecosystems, Pollution, Sustainability, EIA and the Carbon Agenda
2. Environmental pollution: types, causes, controls and abatement
Pollution is the introduction into the environment of a substance or form of energy, beyond what the environment can absorb, that harms health, living things or materials. Pollutants are classed as primary (emitted directly: CO, SO₂, NO, particulates, lead) or secondary (formed in the atmosphere: ground-level ozone and PAN from nitrogen oxides and volatile organic compounds in sunlight, acid aerosols from SO₂ and nitrogen oxides). Sources are point (a chimney, an outfall) or non-point, that is diffuse (farm runoff, street dust). PM10 and PM2.5 are particles with an aerodynamic diameter up to 10 and 2.5 micrometres; the finer fraction penetrates deep into the lungs. A temperature inversion caps the mixing layer and traps pollutants near the ground.
| Type | Main causes | Typical controls and abatement |
|---|---|---|
| Air | Vehicles, thermal power, industry, construction dust, burning of biomass and refuse | Cleaner fuels; electrostatic precipitators, bag filters, cyclones and scrubbers at source; catalytic converters and emission norms; public transport; green buffers; land-use separation |
| Water | Untreated sewage and industrial effluent; farm runoff carrying fertiliser and pesticide | Sewage treatment (primary, secondary biological, tertiary); effluent standards; constructed wetlands; reuse of treated water |
| Noise | Traffic, industry, construction, aircraft, loudspeakers | Zoning and distance; silence zones; barriers and earth berms; buffer planting; source silencing; sound insulation |
| Land and solid waste | Dumping, mining, agrochemicals, plastics, construction and demolition debris | Waste hierarchy (reduce, reuse, recycle, recover); segregation at source; composting; sanitary landfill as last resort; remediation of contaminated land |
| Thermal and light | Cooling water from power plants; excessive or unshielded lighting | Cooling ponds and towers; shielded, downward-directed lighting |
In water, dissolved oxygen (DO) supports aquatic life. BOD (biochemical oxygen demand) is the oxygen that microbes consume in decomposing organic matter, measured by the standard 5-day test at 20 °C; a high BOD means a heavy organic load and falling DO. COD is the oxygen needed for chemical oxidation and is usually larger than BOD for the same sample. Excess nitrogen and phosphorus cause eutrophication: an algal bloom, then oxygen depletion when the algae die and decay.
Abatement strategy. Prefer prevention at the source (a cleaner process, less waste) over minimisation, minimisation over treatment, and treatment over safe disposal. Act at three points: at the source (silencer, filter, process change), along the path (barrier, buffer, dilution distance) and at the receptor (insulation, masks, relocation). The planner’s own levers are land use (keep industry apart from homes, silence zones around hospitals and schools), transport (public transit, non-motorised mobility) and green infrastructure.
Two calculations to know. (1) Air quality index. India’s national AQI runs from Good (0–50) through Satisfactory, Moderately polluted, Poor and Very poor to Severe (401–500). The reported AQI is the highest of the sub-indices of the individual pollutants, and each sub-index is interpolated linearly inside its breakpoint band: I = (I_hi − I_lo)/(BP_hi − BP_lo) × (C − BP_lo) + I_lo. For a band of 60–90 µg/m³ mapped to 100–200 and C = 72, I = (100/30) × 12 + 100 = 140. (2) Decibels. Sound levels add on an energy basis: L = 10 log₁₀ Σ 10^(Lᵢ/10). Two equal sources add 3 dB; n equal sources add 10 log₁₀ n. Three machines of 80 dB each give 80 + 10 log₁₀ 3 = 84.8 dB.
3. Sustainable development goals and strategies
The Sustainable Development Goals were adopted by the United Nations General Assembly in 2015 as the 2030 Agenda: 17 goals and 169 targets. They are universal (they apply to every country), integrated (progress on one depends on others) and pledge to leave no one behind. They succeeded the eight Millennium Development Goals (2000–2015) and are summarised as the five Ps: people, planet, prosperity, peace and partnership.
| Goal | Title | Planning relevance |
|---|---|---|
| SDG 6 | Clean water and sanitation | Water supply, sewerage, reuse of wastewater, watershed protection |
| SDG 7 | Affordable and clean energy | Renewable energy, energy-efficient buildings and districts |
| SDG 9 | Industry, innovation and infrastructure | Resilient infrastructure, sustainable industrialisation |
| SDG 11 | Sustainable cities and communities | Housing, transport, heritage, disaster resilience, air quality, waste, green public space |
| SDG 12 | Responsible consumption and production | Waste reduction, circular use of materials |
| SDG 13 | Climate action | Mitigation and adaptation in plans and buildings |
| SDG 15 | Life on land | Forests, biodiversity, land degradation, ecosystem protection |
Strategies that planners can actually deliver: compact, mixed-use, transit-oriented growth; resource-efficient and climate-responsive buildings; renewable energy and decentralised water and waste systems; protection of green–blue networks and farmland; reuse of brownfield and under-used land before greenfield land; and participatory planning that includes the poor. SDG 11 is the goal that names cities, but a planner touches almost every goal.
4. Climate change and the built environment
Climate change and the built environment. The greenhouse gases are carbon dioxide, methane, nitrous oxide, fluorinated gases and water vapour. The natural greenhouse effect makes the earth habitable; burning fossil fuels, making cement and steel, and clearing forests enhance it. Buildings and construction use large shares of energy and materials in two ways: operational (heating, cooling, lighting) and embodied (extracting, making and transporting materials, and construction itself). Cities are both cause and victim: heat waves, urban flooding, water stress and, on the coast, sea-level rise and storm surge.
- Mitigation (cut emissions): passive and energy-efficient design, renewable energy, retrofitting, low-carbon materials, compact transit-oriented form, urban forests as carbon sinks.
- Adaptation (live with the change): raised plinths and flood-resilient design, setbacks from flood and coastal hazard zones, drainage and retention capacity, mangrove and wetland restoration, cool roofs and shade, early warning.
Frameworks to recognise. The UN Framework Convention on Climate Change (1992); the Kyoto Protocol (1997), which set binding targets for developed countries; and the Paris Agreement (adopted 2015), which aims to hold the rise in global temperature well below 2 °C above pre-industrial levels and to pursue 1.5 °C, through nationally determined contributions (NDCs) renewed on a five-year cycle. India’s National Action Plan on Climate Change (2008) has eight national missions, among them the National Solar Mission and the National Mission on Sustainable Habitat.
5. The urban ecosystem approach, ecological footprint, carrying capacity and resource management
The urban ecosystem approach treats a city as an ecosystem with a metabolism: inputs of energy, water, food and materials, and outputs of wastewater, solid waste, emissions and heat (Abel Wolman’s “metabolism of cities”, 1965). Most cities run a linear metabolism, take–use–dispose, and lean on a distant hinterland for supply and for disposal. The aim is a circular metabolism: treated wastewater reused, organic waste composted or turned into biogas, materials recovered, and a green–blue network of parks, trees, wetlands and water bodies that does the work of cooling, flood storage, air cleaning and habitat. The services such systems provide are grouped as provisioning (water, food), regulating (climate, floods, air), supporting (soil formation, nutrient cycling) and cultural (recreation, identity).
Carrying capacity (K) is the largest population that an environment can support indefinitely without degrading its resource base. In logistic growth, dN/dt = rN(1 − N/K), growth is zero at N = K and greatest at N = K/2, where it equals rK/4. A population can overshoot K for a while by drawing down stocks (soil, groundwater, forests), but decline follows. A city’s carrying capacity is not set by its own boundary, because trade imports capacity from elsewhere; that is exactly what the footprint measures.
Ecological footprint (Rees and Wackernagel) is the area of biologically productive land and water needed to produce the resources a population consumes and to absorb its wastes, expressed in global hectares (gha). Its components are cropland, grazing land, forest products, fishing grounds, built-up land and a carbon component, the forest area needed to take up the CO₂ emitted from fossil fuels. Biocapacity is the supply of such land. Ecological deficit = footprint − biocapacity; a deficit means the population is living on imports or on its natural capital (overshoot). Total footprint = per-capita footprint × population, and the number of “Earths” needed = per-capita footprint ÷ the biocapacity available per person worldwide. Worked example: a city of 2.5 million people with a footprint of 1.6 ha per person, on a territory of 400 km² (40,000 ha), has a footprint of 2.5 × 10⁶ × 1.6 = 4.0 × 10⁶ ha, which is 4.0 × 10⁶ ÷ 40,000 = 100 times the city’s own area.
- Classify the resource: renewable (water, forests, sunlight) or non-renewable (fossil fuels, minerals). The first is managed to a sustainable yield; the second is used sparingly and substituted.
- Use the waste hierarchy and the 3Rs: reduce first, then reuse, then recycle; recover energy only from what cannot be reused; landfill comes last.
- Manage demand before supply: efficiency, metering, reuse and rainwater harvesting cost less than new sources, in water and in energy alike.
- Manage commons collectively: open-access resources are over-used when each user gains and the cost is shared (Hardin’s tragedy of the commons), so rules, tenure or community institutions are needed.
- Manage by system, not by boundary: the watershed, not the municipal limit, is the unit for water; the airshed is the unit for air.
6. Life cycle analysis and the principles of the circular economy
Life cycle analysis (LCA), standardised in ISO 14040 and 14044, evaluates the environmental effects of a product, material or building over its whole life in four phases. (1) Goal and scope definition fixes the purpose, the functional unit (for example, one square metre of wall giving a stated thermal resistance for 50 years) and the system boundary. (2) Life cycle inventory (LCI) compiles the inputs (energy, materials, water) and outputs (emissions, waste) of every stage. (3) Life cycle impact assessment (LCIA) converts the inventory into impact categories such as global warming, acidification and resource depletion. (4) Interpretation draws conclusions and tests sensitivity.
| Boundary | Covers | Typical use |
|---|---|---|
| Cradle-to-grave | Raw-material extraction, manufacture, transport, construction, use, demolition and disposal | Whole-life comparison of buildings or products |
| Cradle-to-gate | Extraction up to the factory gate; use and end of life left out | Environmental product declarations for materials such as cement or steel |
| Gate-to-gate | One process or one factory step only | Improving a single manufacturing process |
| Cradle-to-cradle | As cradle-to-grave, but end of life returns the material to a new cycle by reuse or recycling | Closed-loop and circular design |
For a building the stages are the product stage (extraction, transport and manufacture of materials), construction, the use stage (operational energy and water, maintenance, repair, replacement), end of life (demolition, waste processing, disposal) and the benefits of reuse and recycling beyond the system boundary. Operational impact falls as buildings become more efficient and grids greener, so the embodied share rises in importance. That is why an LCA often shows that keeping and reusing an existing building beats demolishing it for a new, efficient one.
A circular economy replaces the linear take–make–dispose model. The Ellen MacArthur Foundation states three principles: design out waste and pollution; keep products and materials in use; and regenerate natural systems. Materials move in two loops: the biological cycle (nutrients return to the soil through composting and regeneration) and the technical cycle (products are kept at their highest value by maintenance, reuse, repair, refurbishment, remanufacture and, last of all, recycling). In construction this means design for disassembly and adaptability, standard reusable components, adaptive reuse of existing buildings, recycling of construction and demolition waste, “urban mining” of old buildings as a store of materials, and industrial symbiosis, in which one factory’s waste is another’s raw material.
7. Environmental Impact Assessment
Environmental Impact Assessment (EIA) is a systematic process of identifying, predicting and evaluating the environmental and social consequences of a proposed project before a decision is taken, and of proposing measures to avoid, reduce or compensate for them. It is predictive and preventive: harm that is cheap to design out is costly to reverse once a project is built. EIA began with the US National Environmental Policy Act (1969). In India it rests on the Environment (Protection) Act, 1986, and the process is governed by the EIA Notification of 2006 (as amended), which replaced the 1994 notification.
| Stage | What happens | Outcome |
|---|---|---|
| 1. Screening | Decides whether a project needs an EIA. Category A projects always go through the full EIA; Category B projects are screened by the State-level committee into B1 (EIA required) and B2 (no EIA) | Category and decision to proceed |
| 2. Scoping | Identifies the key issues, alternatives, study area and baseline data to be covered; the expert committee approves the terms of reference | Terms of reference (ToR) for the EIA study |
| 3. Public consultation | A public hearing near the site and written responses on the draft EIA report; concerns are answered in the final report | Final EIA report with the environmental management plan |
| 4. Appraisal | The expert appraisal committee reviews the final report, the hearing outcome and the management plan and recommends; the regulatory authority decides on environmental clearance, with conditions | Clearance with conditions, or rejection |
Inside the technical study. The consultant collects baseline data (air, water, noise, soil, ecology, socio-economy), then identifies impacts with checklists, matrices, networks or map overlays. The Leopold matrix lists project actions against environmental factors and scores each interaction for magnitude and importance on a scale of 1 to 10. Impacts are then predicted (dispersion and noise models, hydrological models), evaluated for significance, and mitigated in the order avoid, minimise, restore, compensate. Alternatives, including the no-project option, must be compared.
The Environmental Management Plan (EMP) is the part that binds the developer. It lists each impact, its mitigation measure, the design or construction stage at which the measure applies, who is responsible, the cost and budget, the monitoring programme (parameters, locations, frequency, standards), and emergency and disaster management arrangements. Clearance conditions are enforced through it, and monitoring reports and audits close the loop after commissioning.
8. Carbon footprint and carbon credits
A carbon footprint is the total greenhouse-gas emission caused by a person, organisation, building, event or product, expressed as CO₂ equivalent (CO₂e) by weighting each gas by its global warming potential over a stated horizon (usually 100 years). Methane and nitrous oxide warm the climate many times more strongly per tonne than CO₂, and the exact multipliers differ between assessment reports, so a problem must state them. The basic calculation is emission = activity data × emission factor. Worked example: an office that uses 20,000 kWh of grid electricity at 0.80 kg CO₂/kWh and 1,000 litres of diesel at 2.7 kg CO₂/litre emits 16,000 + 2,700 = 18,700 kg = 18.7 tonnes of CO₂.
| Scope | Meaning | Example for a campus |
|---|---|---|
| Scope 1 | Direct emissions from sources the organisation owns or controls | Boiler fuel, generator diesel, institution-owned vehicles |
| Scope 2 | Indirect emissions from purchased electricity, steam, heating and cooling | Grid electricity used in the buildings |
| Scope 3 | All other indirect emissions in the value chain | Materials and construction, staff commuting, business travel, waste disposal |
A carbon credit is a tradable certificate for one tonne of CO₂e reduced, avoided or removed. Do not confuse it with an allowance, the permit to emit one tonne that a regulator hands out under a cap-and-trade scheme. In compliance markets (regulated schemes, and the Kyoto Protocol’s Clean Development Mechanism, which issued Certified Emission Reductions) buyers use credits and allowances to meet legal limits; in voluntary markets companies buy credits verified by independent standards to offset residual emissions. Credits earned = baseline emissions − project emissions. A credit is credible only if the reduction is additional (it would not have happened without the credit revenue), permanent, free of leakage (not simply moved elsewhere), measured and verified, and not double-counted. The mitigation order is avoid, reduce, and only then offset. Article 6 of the Paris Agreement provides for cooperation between countries through market and non-market approaches.
9. The urban heat island
An urban heat island (UHI) is an urban area that is warmer than its rural surroundings. Its intensity is ΔT = T(urban) − T(rural), and it is largest on clear, calm nights a few hours after sunset. The causes are dark, low-albedo surfaces that absorb sunshine; high-thermal-mass materials (concrete, asphalt, brick) that store heat by day and release it at night; loss of vegetation and soil moisture, hence less cooling by evapotranspiration; street canyons whose low sky view factor traps outgoing long-wave radiation and cuts the wind; anthropogenic heat from air conditioners, vehicles and industry; and a haze of pollutants. The surface UHI (measured by satellite thermal imagery) is strongest by day; the air UHI is strongest at night.
- Cool roofs and pavements: high solar reflectance and high thermal emittance; the Solar Reflectance Index rates a surface from 0 (standard black) to 100 (standard white).
- Trees, green roofs and green walls: shade plus evapotranspiration, which cools by day and at street level.
- Parks and water bodies, linked into the green–blue network so that cool air can reach the dense core.
- Ventilation corridors aligned with the prevailing wind, and building form that avoids a continuous wall of tall blocks.
- Less anthropogenic heat: efficient cooling, public transport, and shading that reduces air-conditioning load.
Albedo arithmetic. Absorbed solar flux = (1 − α) × incident flux, where α is the albedo. With 800 W/m² falling on an old asphalt surface (α = 0.10) the surface absorbs 720 W/m². On a cool-roof coating (α = 0.60) it absorbs 320 W/m², so the absorbed load falls by 400 W/m², which is more than half.
Key takeaways
- Energy flows one way through an ecosystem and about 10% passes up each trophic level; matter cycles. Man-made ecosystems need external energy and material subsidies and export their wastes, and sustainability asks that environment, economy and equity be served together.
- Abate pollution at the source first, then along the path, then at the receptor. Know primary versus secondary pollutants, BOD, the AQI rule (the highest sub-index wins) and that decibels add logarithmically.
- There are 17 SDGs (SDG 11 is sustainable cities and communities, SDG 13 is climate action). Mitigation lowers future emissions; adaptation lowers harm from change already coming. Paris aims well below 2 °C and pursues 1.5 °C through NDCs.
- Treat the city as an ecosystem with a metabolism and move it from linear towards circular. The footprint (global hectares) set against biocapacity gives the ecological deficit; carrying capacity K gives maximum logistic growth at K/2.
- LCA has four phases (goal and scope, inventory, impact assessment, interpretation) and the boundary decides the answer. The circular economy designs out waste, keeps materials in use and regenerates nature, and recycling is its last loop.
- In India EIA runs screening, scoping, public consultation and appraisal; scoping gives the terms of reference, the EMP binds the developer, and the committee recommends while the regulator decides. Carbon footprint is activity data times an emission factor; a credit is one verified, additional tonne of CO₂e; and the UHI peaks at night, driven by stored heat, trapped radiation and lost evapotranspiration.
Practice questions (20)
Attempt each one before opening the answer. Every explanation names the tempting wrong option as well as the right one, because that is where marks are lost.
Compared with a natural forest, a man-made ecosystem such as an irrigated farm or a city is best characterised by
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Answer: C — dependence on continuing external inputs of energy, water and materials, with its wastes exported
Farms and cities run on subsidies (fuel, electricity, fertiliser, water) and export their wastes, so they are open, simplified systems that need continuous management. The tempting alternative, higher diversity and stability, describes the natural forest, not the man-made system. Decomposers are present in both.Under the 2030 Agenda of the United Nations, which pair correctly names Goal 11 and Goal 13?
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Answer: A — SDG 11: sustainable cities and communities; SDG 13: climate action
Goal 11 is sustainable cities and communities and Goal 13 is climate action. Responsible consumption and production is Goal 12 and life on land is Goal 15; a pair with one name right and the other wrong is the usual trap.A planner wants to move a city from a linear towards a circular urban metabolism. Which package of measures does this best?
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Answer: C — Reuse of treated wastewater, composting and biogas from organic waste, and a green–blue network for flood storage and cooling
A circular metabolism returns outputs as inputs: treated water, compost and biogas, and natural systems doing the work of storage and cooling. Larger landfills, sprawl onto farmland, and incineration with groundwater mining all increase one-way throughput and dependence on the hinterland. Burning mixed waste recovers some energy but destroys the materials, which ranks low in the value hierarchy.Which of the following statements about ecological footprint and carrying capacity are correct? Select all that apply.
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Answer: A — The footprint is the area of productive land and water needed to supply a population’s consumption and absorb its waste.; B — A footprint larger than local biocapacity shows that the population relies on imports or is drawing down natural capital.; D — The carbon component of the footprint is the area of forest needed to absorb the CO₂ emitted from fossil fuels.
The definition of the footprint, the meaning of a deficit and the carbon component are all standard. The statement that carrying capacity is fixed by the administrative area is false: trade imports capacity, which is why a city’s footprint can be many times its own area.Producers in a grassland fix 20,000 kJ of energy per square metre per year. If 10% of the energy is transferred at each step of the food chain, the energy reaching the fourth trophic level, in kJ per square metre per year, is ____.
Numerical answer — type the value.
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Answer: 20
Trophic level 1 holds 20,000 kJ; level 2 receives 20,000 × 0.1 = 2,000; level 3 receives 200; level 4 receives 20. There are three transfers, so 20,000 × 0.1³ = 20 kJ. The common slip is to count four transfers and answer 2.A town of 1.2 million people has an average ecological footprint of 2.0 hectares of bioproductive land per person. The town’s own territory is 300 km². The town’s footprint is how many times its own area? ____
Numerical answer — type the value.
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Answer: 80
Total footprint = 1.2 × 10⁶ × 2.0 = 2.4 × 10⁶ ha. The territory is 300 km² = 300 × 100 = 30,000 ha, since 1 km² = 100 ha. Ratio = 2.4 × 10⁶ ÷ 30,000 = 80. Treating 1 km² as 1 ha would wrongly give 8,000.Which of the following is a secondary air pollutant, formed in the atmosphere by reactions driven by sunlight rather than emitted directly by a source?
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Answer: D — ground-level ozone formed from nitrogen oxides and volatile organic compounds
Ground-level ozone is not emitted; it forms when nitrogen oxides and volatile organic compounds react in sunlight. Carbon monoxide, lead and SO₂ are emitted directly, so they are primary. The tempting choice is SO₂, which can later form sulphate aerosol, but SO₂ itself is a primary pollutant.A town wants to remove dissolved and colloidal organic matter from its sewage after screening, grit removal and primary settling. Which stage does this, and how?
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Answer: B — Secondary biological treatment, in which microorganisms oxidise the organic matter and so lower the BOD
Dissolved and colloidal organics do not settle out. Aerobic microbes in an activated sludge plant or trickling filter consume them, which lowers the BOD. Disinfection kills pathogens but is not how organics are removed, and tertiary polishing comes after the secondary stage, not before it.Under the EIA Notification of 2006, the stages of the clearance process for a project that requires a full EIA run in the order
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Answer: A — screening, scoping, public consultation, appraisal
Screening decides whether an EIA is needed; scoping fixes the terms of reference for the study; public consultation tests the draft EIA report and the management plan; and the expert committee’s appraisal comes last, before the regulator decides. Consultation cannot come before scoping, because there is no draft report until the study has been done.Which of the following statements about EIA in India are correct? Select all that apply.
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Answer: A — Scoping fixes the terms of reference for the EIA study, including the key issues, alternatives and baseline data to be covered.; C — EIA is a predictive tool that assesses a proposed project before the decision, whereas the assessment of policies and plans is called strategic environmental assessment.
Scoping sets the terms of reference, and EIA is project-level and predictive while strategic environmental assessment covers plans and policies. A public hearing is a consultation whose outcome must be addressed in the final report; it is not a vote. The management plan is part of the EIA report and is appraised before clearance, while its monitoring continues after commissioning.Five identical machines each produce a sound level of 60 dB at a receiver when run alone. The combined level when all five run together, in dB to the nearest whole number, is ____.
Numerical answer — type the value.
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Answer: 67
L = 10 log₁₀(5 × 10⁶) = 60 + 10 log₁₀ 5 = 60 + 6.99 = 66.99, which is 67 dB to the nearest whole number. Adding 5 × 60 = 300 dB is the mistake: sound energies add, not decibel values.For one pollutant, concentrations between 60 and 120 µg/m³ are mapped linearly to sub-index values between 100 and 200. Using I = (I_hi − I_lo)/(BP_hi − BP_lo) × (C − BP_lo) + I_lo, the sub-index at C = 96 µg/m³ is ____.
Numerical answer — type the value.
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Answer: 160
I = (200 − 100)/(120 − 60) × (96 − 60) + 100 = (100/60) × 36 + 100 = 60 + 100 = 160. The reported AQI takes the highest of the pollutant sub-indices, not their average.In an LCA of a school building, the team tabulates the quantities of cement, steel, diesel, electricity and water used, and the emissions released, for each stage, per square metre of floor area. This is the phase called
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Answer: C — life cycle inventory analysis, which quantifies the inputs and outputs of each stage
Compiling quantified inputs and outputs is the inventory (LCI). Converting them into global-warming or acidification scores is impact assessment, which is the tempting step; goal and scope come first and fix the purpose, functional unit and boundary.A campus (i) burns diesel in its own generators, (ii) buys grid electricity, (iii) buys cement and steel for a new hostel block, and (iv) runs university-owned buses. Under the Greenhouse Gas Protocol the correct classification is
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Answer: D — Scope 1: diesel and buses; Scope 2: grid electricity; Scope 3: cement and steel
Diesel burnt in the campus’s own equipment and in its own buses are direct emissions (Scope 1). Purchased electricity is an indirect emission from energy generated elsewhere (Scope 2). The manufacture of purchased materials is a value-chain emission (Scope 3). The common trap is to call grid electricity Scope 1 because the campus uses it, when the emission occurs at the power plant.A developer claims carbon credits for a rooftop solar plant that was already financially viable and would have been built anyway. The credits are most likely to be rejected because the project fails the test of
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Answer: B — additionality, since the reduction would have occurred without the carbon revenue
Additionality asks whether the project happened because of the credit revenue; a plant that was viable and already planned delivers no extra reduction. Permanence and leakage concern reversal and displacement of emissions, and double counting concerns two claims on one credit; none of these is described.The air-temperature urban heat island intensity of a city is usually greatest
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Answer: A — on clear, calm nights a few hours after sunset, when rural areas cool quickly and the city releases stored heat
On clear calm nights rural surfaces lose heat quickly by radiation, while the city, with its high thermal mass and low sky view factor, cools slowly, so the temperature difference peaks. Wind and cloud both reduce the contrast. It is the air heat island that peaks at night; the surface heat island seen by satellites is stronger by day.For a low-lying coastal city, which measure is climate adaptation rather than mitigation?
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Answer: D — restoring mangroves and fixing minimum plinth levels in flood-prone zones to reduce storm-surge damage
Adaptation lowers harm from change that is already coming; mangroves and plinth levels reduce storm-surge and flood damage. Solar panels, the energy-use cap and metro extension all lower future emissions, so they are mitigation.Which of the following reduce the urban heat island effect? Select all that apply.
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Answer: A — replacing dark roofing with high-albedo, high-emittance cool roofs; B — increasing tree canopy and providing green roofs and green walls
Cool roofs reduce the solar radiation absorbed, and trees and green roofs add shade and evapotranspiration. Replacing greenery with asphalt adds heat storage and removes evaporative cooling, and a continuous wall of tall blocks across the wind cuts ventilation and traps heat.Which of the following are principles of the circular economy as set out by the Ellen MacArthur Foundation? Select all that apply.
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Answer: B — keeping products and materials in use at their highest value; C — designing out waste and pollution; D — regenerating natural systems
The three principles are to design out waste and pollution, to keep products and materials in use, and to regenerate natural systems. Maximising virgin extraction is the logic of the linear model, not the circular one.A hostel uses 50,000 kWh of grid electricity a year at an emission factor of 0.80 kg CO₂ per kWh, and burns 2,000 litres of diesel in its generator at 2.7 kg CO₂ per litre. Its annual carbon footprint from these two sources, in tonnes of CO₂ to one decimal place, is ____.
Numerical answer — type the value.
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Answer: 45.4
Electricity: 50,000 × 0.80 = 40,000 kg. Diesel: 2,000 × 2.7 = 5,400 kg. Total = 45,400 kg = 45.4 tonnes of CO₂. Remember to divide by 1,000 to convert kilograms to tonnes.