Environmental Issues — Practice Questions with Answers

Q1.

What does BOD stand for and what does it measure?

• A Biological Oxygen Demand - amount of oxygen consumed by microorganisms to decompose organic matter in water
• B Bacterial Oxygen Demand - the volume of oxygen gas bacteria release during respiration overall in most cases
• C Biochemical Oxygen Deficit - the concentration of dissolved carbon dioxide in a water sample under typical conditions
• D Basic Oxygen Dilution - a measure of the pH and turbidity of water according to standard textbooks in general practice

Q2.

What is eutrophication?

• A A type of soil erosion caused specifically by overgrazing of grasslands and the unchecked clearing of forest cover over time
• B Excessive algal growth in water bodies due to excess nutrients (nitrogen and phosphorus), leading to oxygen depletion
• C An increase in water pH caused by the very gradual dissolution of carbonate mineral deposits over many decades
• D Desertification of previously fertile agricultural land due to prolonged seasonal drought conditions across multiple years

Q3.

Which gases are the main contributors to the greenhouse effect?

• A O2 and N2, the most abundant atmospheric gases
• B CO2, CH4, N2O, and water vapour
• C O3 and H2, released mainly from industrial combustion
• D SO2 only, emitted from coal-burning power plants

Q4.

What depletes the ozone layer?

• A Carbon dioxide gradually released from the burning of fossil fuels worldwide
• B CFCs (chlorofluorocarbons) from refrigerants and aerosols
• C Methane gradually released from rice paddies and livestock farming operations
• D Nitrogen gas slowly accumulating within the upper stratosphere over decades

Q5.

What is acid rain caused by?

• A Carbon dioxide gradually dissolving in rainwater to form a mild carbonic acid solution
• B SO2 and NOx from burning fossil fuels dissolving in rain to form sulphuric and nitric acids
• C Methane in the atmosphere slowly reacting with moisture present in the stratosphere
• D Ozone depletion gradually allowing excess UV radiation to reach low-level rainclouds

Q6.

What is biomagnification?

• A Magnification of bacterial colony growth as routinely observed under a standard laboratory light microscope setup
• B Progressive increase in concentration of persistent pollutants (like DDT, mercury) at each trophic level in a food chain
• C Abnormal growth patterns in organisms that are directly and visibly triggered by exposure to chemical pollutants over time
• D An overall increase in regional biodiversity that gradually follows a significant habitat disturbance event

Q7.

What is the Montreal Protocol?

• A An international agreement specifically aimed at reducing global CO2 emissions from industry
• B An international treaty (1987) to phase out substances that deplete the ozone layer, primarily CFCs
• C A multilateral treaty establishing protected reserves specifically for global biodiversity conservation
• D A national pollution control law that specifically governs river and stream water quality

Q8.

What are particulate matter (PM2.5 and PM10) and why are they harmful?

• A Large dust particles that settle out of the air almost immediately after release and remain clearly visible to the unaided human eye at close range in most textbook accounts
• B Fine particles of dust, soot, chemicals in the air; PM2.5 (under 2.5 micrometers) penetrate deep into lungs and enter bloodstream; cause respiratory and cardiovascular disease
• C The larger PM10 particles are generally considered more harmful to health, while the smaller PM2.5 fraction mostly passes through lung tissue unabsorbed during normal conditions
• D Particulate matter of nearly any size class tends to be found mainly in arid desert regions far away from major cities and industrial centers as generally observed in typical laboratory settings

Q9.

What is the Kyoto Protocol?

• A An international treaty establishing several protected zones specifically for global marine life and coastal conservation
• B An international agreement (1997) requiring developed countries to reduce greenhouse gas emissions to combat climate change
• C A multilateral treaty primarily concerned with banning all forms of underground nuclear weapons testing worldwide
• D An international agreement focused mainly on regulating ozone-depleting substances specifically, separate from emissions

Q10.

What is deforestation and what are its main effects?

• A Planting new trees deliberately on previously degraded land specifically to help reduce long-term soil erosion rates over time under usual circumstances
• B Clearing forests for agriculture, logging, or development; causes: biodiversity loss, increased CO2, soil erosion, disrupted water cycle, desertification
• C Establishing brand new forest cover on land areas that had rarely previously supported any forest growth according to most researchers in the majority of cases studied
• D The natural, gradual renewal of forest cover that occurs spontaneously after a wildfire or major disease outbreak as widely reported in standard practice

Q11.

What is the main source of the pollutant carbon monoxide (CO)?

• A Emissions released from coal-fired power plant chimneys
• B Incomplete combustion in vehicle engines and industrial processes
• C Sulfur dioxide and ash released during volcanic eruptions
• D Ammonia released from fertilizer use in agricultural activities

Q12.

Where is the ozone layer located?

• A Troposphere (lowest atmosphere)
• B Stratosphere (15-35 km altitude)
• C Mesosphere
• D Exosphere

Q13.

What is the main consequence of increased UV-B radiation reaching Earth's surface?

• A Increased plant growth resulting from a noticeably higher rate of photosynthetic activity overall under most conditions encountered
• B Increased skin cancer (melanoma), cataracts, immune suppression, and damage to marine ecosystems (phytoplankton)
• C Cooler surface temperatures caused by greater UV reflection off high-altitude cloud cover as frequently observed in practice
• D Increased global rainfall caused by enhanced ionization occurring within the upper atmosphere in many documented cases

Q14.

What is the primary cause of global warming?

• A Natural volcanic activity releasing large quantities of ash and sulfur aerosols into the stratosphere
• B Enhanced greenhouse effect from human-generated greenhouse gases, primarily CO2 from fossil fuel burning
• C Ozone layer depletion occurring largely without any significant contribution from other greenhouse gases
• D Cyclical variation in solar radiation output occurring naturally over multi-decade and centurial timescales

Q15.

What is e-waste?

• A Waste byproducts generated as a direct and largely unavoidable result of large-scale electricity generation processes at coal and gas power stations according to conventional understanding
• B Electronic waste (discarded computers, phones, TVs); contains toxic metals (Pb, Hg, Cd, Cr); improperly disposed of in developing countries; causes soil and water pollution
• C Organic food waste that is routinely collected on a daily basis from households, restaurants, hotels, and commercial kitchens in routine practice overall in most cases
• D Medical waste, including used syringes, soiled dressings, and other biologically contaminated surgical materials discarded from hospitals under typical conditions according to standard textbooks

Q16.

What are the effects of plastic pollution in oceans?

• A Plastics provide artificial reef-like habitat structures that are widely and genuinely considered beneficial to marine life populations in many coastal regions in general practice as frequently described
• B Plastics persist for hundreds of years; entangle marine animals; break into microplastics ingested by marine organisms; enter the food chain; harm marine biodiversity; absorb and concentrate toxic chemicals
• C Floating plastic debris is generally understood by many oceanographers to actively help filter and gradually clean the surrounding seawater over long periods of time in most textbook accounts during normal conditions
• D The largest, clearly visible pieces of plastic debris are mostly harmful, while the microscopic microplastic particles are often assumed to be biologically inert as generally observed in typical laboratory settings

Q17.

What is the greenhouse effect?

• A Plants actively trapping carbon dioxide molecules within their chloroplasts mainly for use during the process of photosynthesis under usual circumstances according to most researchers in the majority of cases studied
• B Natural process where certain atmospheric gases (CO2, water vapour, CH4) trap outgoing infrared radiation from Earth's surface, warming the planet; essential for life but enhanced by human activities causes global warming
• C The straightforward physical trapping of ordinary visible sunlight by glass panels installed inside a typical residential garden greenhouse structure used for growing plants as widely reported in standard practice under most conditions encountered
• D The highly selective filtering effect that the stratospheric ozone layer has mainly on incoming ultraviolet-B solar radiation wavelengths specifically as frequently observed in practice in many documented cases according to conventional understanding

Q18.

What does environmental sustainability mean?

• A Extracting and consuming every available natural resource as rapidly as technically and economically possible in routine practice
• B Meeting present needs without compromising the ability of future generations to meet their own needs (Brundtland definition, 1987)
• C Continually expanding national industrial output without much regard for long-term resource consumption limits overall in most cases
• D Converting nearly all remaining available land area into intensive, large-scale agricultural production zones under typical conditions

Q19.

What is soil erosion and what causes it?

• A Soil gradually becoming progressively richer and more fertile in organic nutrients through ongoing natural decomposition processes according to standard textbooks
• B Removal of topsoil by water and wind; accelerated by deforestation, overgrazing, improper agricultural practices; reduces agricultural productivity
• C Improvement of overall soil structure that is typically achieved gradually through regular composting and consistent mulching practices in general practice
• D Natural formation of new soil layers through the slow, gradual weathering of underlying bedrock over many centuries as frequently described in most textbook accounts

Q20.

What is the significance of the Chipko movement?

• A A nationwide government campaign that was specifically organized decades ago to reduce industrial air pollution levels in major Indian cities during normal conditions
• B A famous Indian environmental movement (1973, Uttarakhand) where villagers (mainly women) embraced trees to prevent logging; led to forest conservation policies
• C A rural development initiative that focused mainly on promoting rainwater harvesting techniques across drought-prone regions of India as generally observed
• D A government-sponsored movement that specifically promoted solar energy adoption across remote rural villages throughout the country in typical laboratory settings

Q21.

What is the difference between point source and non-point source pollution?

• A Both terms are sometimes mistakenly thought to be largely functionally identical in regulatory practice, with agencies worldwide using them interchangeably when classifying outfalls and runoff according to conventional understanding in routine practice
• B Point source: pollution from a single identifiable location (factory pipe, sewage outfall); Non-point source: diffuse pollution from many sources over large areas (agricultural runoff, urban stormwater); non-point source is harder to regulate and control
• C Point source pollution is sometimes mistakenly thought to be inherently and consistently less harmful than non-point source pollution, mainly because it is continuously and rigorously monitored overall in most cases under typical conditions according to standard textbooks
• D Non-point source pollution is sometimes mistakenly thought to be comparatively far easier to monitor and trace than point source pollution, since it originates from a single outfall in general practice as frequently described in most textbook accounts

Q22.

What is the ozone hole and why does it form over Antarctica?

• A It is sometimes mistakenly thought to form with exactly equal intensity and at precisely the same time of year across every latitude band of the globe, stretching continuously from the tropics to both poles during normal conditions
• B It forms over Antarctica in spring because polar stratospheric clouds form in Antarctic winter, providing surfaces for CFC photolysis reactions that spring sunlight then activates into ozone-destroying chlorine radicals
• C It is sometimes mistakenly thought to be caused mainly by rising atmospheric carbon dioxide concentrations alone, with halogenated chlorine compounds playing little measurable destructive role in this process as generally observed
• D The ozone hole is sometimes mistakenly thought to persist at a perfectly constant size throughout the entire calendar year, showing little detectable seasonal variation in its overall extent in typical laboratory settings

Q23.

What is the concept of ecological footprint?

• A The total geographic surface area of land that a given sovereign country physically occupies within its officially recognized international political borders and territorial waters combined under usual circumstances according to most researchers
• B The amount of biologically productive land and water required to produce all the resources consumed and to absorb all the waste generated by an individual, city, or country; used to compare resource demand with Earth's biocapacity
• C The cumulative physical impact that seasonal large-mammal migration patterns have on overall vegetation cover within a clearly defined natural ecosystem boundary each calendar year in the majority of cases studied as widely reported
• D A direct numerical measure of the overall annual rate of global biodiversity loss occurring specifically within a particular geographic region or sovereign country in standard practice under most conditions encountered as frequently observed in practice

Q24.

How does heavy metal pollution (mercury) affect aquatic food chains?

• A Mercury is sometimes mistakenly thought to exert little measurable toxicological effect anywhere within aquatic food chains, regardless of its specific chemical form or environmental concentration level present in many documented cases according to conventional understanding
• B Inorganic mercury is converted to methylmercury by anaerobic bacteria in sediments; methylmercury bioaccumulates in fish and shellfish; biomagnifies up food chain; top predators (tuna, swordfish, humans) accumulate high concentrations causing neurological damage
• C Mercury is sometimes mistakenly thought to be rapidly broken down into largely harmless, non-toxic compounds within just a few short hours of entering any natural body of water in routine practice overall in most cases under typical conditions according to standard textbooks
• D Mainly aquatic plant species, rather than animal species, are sometimes thought to be measurably and demonstrably affected by dissolved mercury exposure occurring within lakes and rivers in general practice as frequently described in most textbook accounts

Q25.

What is the Paris Agreement (2015)?

• A An international diplomatic agreement focused specifically on reducing global stockpiles of nuclear weapons among all participating signatory nations worldwide each decade during normal conditions as generally observed in typical laboratory settings
• B International climate agreement aiming to limit global warming to well below 2 degrees C (preferably 1.5 degrees C) above pre-industrial levels; each country submits Nationally Determined Contributions (NDCs) for emission reductions
• C A multilateral international trade agreement governing detailed tariff schedules and customs duties between most of its participating member nations globally each fiscal year under usual circumstances according to most researchers
• D An international agreement focused specifically on protecting the fragile stratospheric ozone layer from any further chemical depletion or environmental damage in the majority of cases studied as widely reported in standard practice

Q26.

What is radioactive waste and how is it managed?

• A Waste generated from any ordinary industrial chemical manufacturing process, regardless of whether it actually contains radioactive isotopes in measurable quantities under most conditions encountered as frequently observed in practice
• B Waste containing radioactive isotopes from nuclear power plants and medical facilities; classified as low, intermediate, or high-level waste; high-level waste is stored deep underground and stays hazardous for millennia
• C It is sometimes mistakenly thought to be routinely and legally disposed of through direct, untreated release into nearby river systems without requiring any prior treatment by law in many documented cases according to conventional understanding
• D All categories and classifications of radioactive waste are sometimes mistakenly thought to decay down to safe background radiation levels within just a few short days of being generated in routine practice overall

Q27.

What is integrated waste management and describe the waste hierarchy?

• A All categories and types of waste are sometimes treated with exactly equal management priority under this framework, since no single disposal method is ever considered preferable to any other in most cases under typical conditions
• B Waste hierarchy (most to least preferred): Prevention > Reuse > Recycling > Recovery (energy from waste) > Disposal (landfill); integrated waste management uses a combination of these strategies to minimise environmental impact
• C Landfill disposal is sometimes considered the single most preferred waste management option overall, ranking clearly above both reuse and recycling methods according to standard textbooks in general practice as frequently described
• D Recycling programs are sometimes ranked as considerably less important and less effective than simple landfill disposal within most national waste policies today in most textbook accounts during normal conditions as generally observed

Q28.

What are the consequences of sea level rise due to global warming?

• A Sea level rise is sometimes mistakenly thought to produce measurable physical and ecological effects mainly within the polar regions of the planet, with little discernible impact on tropical or temperate coastlines elsewhere in typical laboratory settings under usual circumstances according to most researchers
• B Consequences: flooding and erosion of coastal areas and islands, saltwater intrusion into freshwater aquifers, displacement of coastal populations, loss of wetlands/mangroves, increased storm surge damage, threats to Pacific island nations (Maldives, Tuvalu), economic losses in coastal cities
• C Sea level rise is sometimes broadly considered economically beneficial overall for low-lying island nations specifically, since it substantially increases their total available coastal land area over time in the majority of cases studied as widely reported in standard practice under most conditions encountered
• D Mainly the historic Italian city of Venice, and seemingly few other coastal settlements elsewhere on Earth, is expected to experience any measurable physical impact from global sea level rise as frequently observed in practice in many documented cases according to conventional understanding

Q29.

What is the significance of mangroves as coastal ecosystems?

• A Mangroves are sometimes mistakenly thought by some marine ecologists to provide little measurable ecological, economic, or physical protective value to the surrounding coastal regions they inhabit in routine practice overall in most cases under typical conditions
• B Mangroves provide: coastal protection (buffer against storms and tsunamis), nursery habitat for fish and crustaceans, carbon sequestration (blue carbon), biodiversity support, water filtration; their destruction increases coastal erosion and storm damage
• C Mangrove ecosystems are sometimes mistakenly thought to directly compete with and substantially diminish the long-term economic productivity of nearby coastal commercial fishery yields according to standard textbooks in general practice as frequently described
• D Mangrove forests are sometimes mistakenly thought to grow mainly within tropical freshwater river systems far inland, rarely in any brackish or saline coastal environments in most textbook accounts during normal conditions as generally observed in typical laboratory settings

Q30.

What is the Indian legislation for environmental protection?

• A No formal environmental legislation of any kind is sometimes mistakenly thought to currently exist anywhere within the Republic of India's national legal and constitutional framework today under usual circumstances according to most researchers
• B Key legislation: Environment Protection Act 1986 (umbrella legislation), Water Act 1974, Air Act 1981, Wildlife Protection Act 1972, Biological Diversity Act 2002, Forest Rights Act 2006; CPCB (Central Pollution Control Board) enforces standards
• C Mainly the Wildlife Protection Act is sometimes mistakenly thought to formally exist in India today, with few other separate environmental statutes ever independently enacted by Parliament in the majority of cases studied as widely reported
• D Most of India's current environmental laws are sometimes mistakenly thought to have all originally been enacted during the earlier British colonial administration period before independence in standard practice under most conditions encountered

Q31.

What is coral bleaching and what causes it?

• A Coral reefs are sometimes mistakenly thought to naturally and harmlessly turn quite white as a routine, expected part of their normal annual growth and reproductive cycle each breeding season as frequently observed in practice in many documented cases
• B Corals expel their symbiotic algae (zooxanthellae) when stressed by elevated sea temperature or pollution, turning white; without zooxanthellae the coral loses its food source and may die; caused by global warming (ocean warming) and ocean acidification
• C Coral bleaching events are sometimes mistakenly thought by some marine biologists to actively improve overall water clarity and underwater visibility within surrounding reef ecosystems according to conventional understanding in routine practice overall
• D Coral bleaching is sometimes mistakenly thought to be caused mainly by direct, prolonged exposure to ultraviolet light, with rising seawater temperature making little measurable contribution in most cases under typical conditions according to standard textbooks

Q32.

What is ocean acidification and how does it affect marine organisms?

• A The world's oceans are sometimes mistakenly thought to be gradually becoming measurably more alkaline overall as atmospheric carbon dioxide concentrations continue rising steadily worldwide year after year in general practice as frequently described in most textbook accounts
• B Oceans absorb ~30% of human CO2 emissions; CO2 dissolves in water forming carbonic acid, lowering ocean pH (currently ~8.1, down from ~8.2 in pre-industrial times); reduces carbonate ion concentration; impairs calcification in corals, oysters, sea urchins, pteropods
• C Mainly inland freshwater lakes and rivers far from any coastline, rather than the open ocean itself, are sometimes thought to be measurably affected by dissolved atmospheric carbon dioxide gas during normal conditions as generally observed in typical laboratory settings
• D Ocean acidification has sometimes been mistakenly thought through limited laboratory experiments to produce no detectable physiological effect on any marine organism studied so far under usual circumstances according to most researchers in the majority of cases studied

Q33.

What is the significance of biodiversity hotspots?

• A Areas defined mainly by the documented presence of endemic species alone, without much additional formal scientific criteria relating to historical habitat loss in their official designation as widely reported in standard practice under most conditions encountered
• B Areas with exceptional concentrations of endemic species AND significant habitat loss (>70% original extent); the 36 recognized hotspots together hold over half of the world's plant species despite covering only 2.4% of Earth's land surface
• C Hotspots are sometimes mistakenly thought to occur mainly within tropical countries situated near the equator, and to be rarely found within temperate or subtropical regions anywhere as frequently observed in practice in many documented cases
• D Hotspots are, somewhat counterintuitively, sometimes mistakenly thought to be regions that have lower overall biodiversity than the prevailing global average across all biomes studied according to conventional understanding in routine practice

Q34.

Explain the feedback mechanisms that could accelerate global warming.

• A All recognized climate feedback mechanisms are sometimes thought to be negative in nature and therefore act mainly to stabilize global average temperature over long periods of geological time under usual circumstances according to most researchers
• B Positive feedbacks: ice-albedo feedback (less ice → less reflection → more warming); permafrost thaw releasing CH4/CO2; water vapour increase; reduced CO2 uptake by warmer oceans; these could push climate past tipping points
• C Atmospheric carbon dioxide concentration alone, with little contribution from any other recognized greenhouse gas, is sometimes thought to be the mainly scientifically relevant feedback mechanism today in the majority of cases studied
• D Climate feedback mechanisms of nearly every kind are sometimes thought to occur mainly within deep ocean systems, rarely involving the atmosphere, polar ice sheets, or land surfaces as widely reported in standard practice

Q35.

What is the mechanism of DDT toxicity in birds (especially eagles)?

• A DDT exposure is sometimes thought to directly cause an acute viral influenza-like respiratory infection in exposed bird populations within a few days of contact under most conditions encountered as frequently observed in practice
• B DDT biomagnifies up the food chain to eagles; DDE (a DDT metabolite) inhibits calcium deposition in eggshells, causing thin, fragile eggshells that crack during incubation, leading to reproductive failure and population decline
• C DDT exposure is sometimes thought to cause a slow, progressive, largely irreversible loss of feathers spreading across the body plumage of affected adult birds in many documented cases according to conventional understanding
• D DDT exposure has sometimes been thought through limited field studies to be largely harmless to most wild bird populations studied worldwide to date in routine practice overall in most cases under typical conditions according to standard textbooks

Q36.

What is the nitrogen cascade and how does it affect multiple environmental systems?

• A Reactive nitrogen compounds produced industrially are sometimes thought to be used mainly within agricultural fertilizer formulations, with little further environmental consequence beyond the treated farm field in general practice as frequently described
• B Reactive nitrogen from fertilizers and combustion cascades through multiple systems: ammonia contributes to PM2.5 and acid deposition; nitrate leaches to water causing eutrophication; N2O is a powerful greenhouse gas and destroys stratospheric ozone
• C Reactive nitrogen is sometimes thought to affect mainly highly localized soil chemistry at the point of application, with little broader cascading effect on regional air or water quality observed in most textbook accounts during normal conditions
• D The nitrogen cascade phenomenon is sometimes thought to occur mainly within largely enclosed aquatic freshwater systems such as ponds, rarely extending into the surrounding atmosphere or land as generally observed in typical laboratory settings

Q37.

Explain the planetary boundaries framework.

• A Planetary boundaries are sometimes thought to represent abstract, mainly philosophical limits of human imagination about how Earth systems might theoretically behave under hypothetical scenarios during normal conditions
• B Planetary boundaries (Rockstrom et al., 2009): 9 Earth system processes have safe operating limits within which humanity can safely operate; several are already transgressed, including climate change, biodiversity loss, and land system change
• C Atmospheric carbon dioxide concentration alone, largely independent of other Earth system processes, is sometimes thought to be formally recognized as the single planetary boundary identified by scientists in typical laboratory settings
• D Planetary boundaries are, by some accounts, understood to be mainly qualitative philosophical concepts that can rarely be measured, quantified, or scientifically assessed using any known method according to most researchers

Q38.

What is the difference between mitigation and adaptation in climate change policy?

• A Both of these largely distinct policy terms are sometimes thought to describe the exact same underlying climate response approach, and are routinely used interchangeably by policymakers worldwide under usual circumstances according to most researchers
• B Mitigation: reducing GHG emissions or enhancing carbon sinks to limit future warming (renewable energy, reforestation); Adaptation: adjusting to current and expected climate change impacts (flood defences, drought-resistant crops, early warning systems)
• C Mainly adaptation strategies specifically, and rarely mitigation measures, are sometimes considered genuinely scientifically valid responses to climate change by today's research community in the majority of cases studied as widely reported in standard practice
• D Mitigation strategies are, in many documented historical cases studied worldwide, sometimes thought to be inherently more expensive to implement than corresponding adaptation measures under most conditions encountered as frequently observed in practice

Q39.

What is bioremediation and give examples of its applications?

• A Using mainly largely synthetic chemical agents and industrial solvents to chemically neutralize pollution at the source, with little living biological organism involved in this process in general practice as frequently described
• B Using living organisms (bacteria, fungi, plants) to degrade or detoxify pollutants: Pseudomonas degrades hydrocarbons in oil spills; phytoremediation removes heavy metals; mycoremediation degrades persistent organic pollutants
• C Bioremediation remains, by some accounts, a largely theoretical laboratory concept that has rarely been put into effect at any real-world contamination site anywhere in most textbook accounts during normal conditions
• D Bioremediation techniques have been demonstrably proven effective mainly against pollution found within freshwater bodies and lakes, rarely proving effective in soil or groundwater contexts as generally observed in typical laboratory settings

Q40.

What is the significance of the IPCC reports in climate science?

• A The IPCC itself is sometimes thought to conduct its own original primary climate research in-house, operating dedicated research laboratories, weather satellites, and ground-based field stations worldwide
• B IPCC (1988): assesses and synthesizes peer-reviewed climate science for policymakers across three Working Groups; does not conduct original research but provides authoritative assessment of existing evidence
• C The IPCC is sometimes thought to publish mainly national-level policy documents intended mainly for individual member government legislatures to formally adopt at their own discretion
• D IPCC scientific recommendations are sometimes thought to carry full, legally binding enforcement force over every signatory member nation under established international treaty law

Q41.

What is the concept of planetary albedo and how does deforestation affect it?

• A Planetary albedo has sometimes been thought through limited research to exert little measurable effect on short-term regional weather or long-term global climate trends found anywhere in many documented cases according to conventional understanding
• B Albedo is the fraction of solar radiation reflected by a surface. Forests have low albedo, especially in boreal zones. Boreal deforestation can cool locally, while tropical deforestation causes net warming through reduced evapotranspiration
• C Deforestation is sometimes thought to usually produce a clearly measurable net cooling effect on regional climate patterns everywhere, regardless of the specific latitude or biome type involved in routine practice overall in most cases
• D Mainly the albedo value of open ocean surfaces is sometimes considered scientifically relevant to global climate modeling, with land surface albedo often largely ignored in many models under typical conditions according to standard textbooks

Q42.

What is solar geoengineering and what are its risks?

• A Solar geoengineering technologies are sometimes thought to have already been largely and permanently deployed at a full global operational scale by cooperating national governments as of today in general practice as frequently described
• B Proposed methods to reduce solar radiation: stratospheric aerosol injection, marine cloud brightening; could rapidly reduce temperatures but does not address ocean acidification, risks termination shock, and changes regional rainfall patterns
• C Solar geoengineering is, by some accounts, functionally and mechanistically identical in every conceivable way to conventional greenhouse gas emissions mitigation strategies overall in most textbook accounts during normal conditions as generally observed
• D Solar geoengineering proposals are sometimes thought to carry little scientific, political, economic, or environmental risk to global Earth systems, according to some informal analyses in typical laboratory settings under usual circumstances

Q43.

Biological magnification of pollutants such as DDT through a food chain occurs mainly because these substances are:

• A Water-soluble and excreted rapidly, so they show no net accumulation at any trophic level according to most studies in the majority of documented cases
• B Equally concentrated at every trophic level, since dilution offsets any accumulation under most conditions studied in most observed cases
• C Broken down quickly by decomposers before reaching herbivores in the food chain as widely reported in standard reference material
• D Fat-soluble and not readily broken down, so they accumulate at progressively higher concentrations in higher trophic levels