Lecture Notes - Systems thinking

Question 1

What is a system?

Answer 1

A system consists of a number of interacting parts. One may consist of several, interdependent systems.

Question 2

Define atmosphere, cryosphere, lithosphere, biosphere, hydrosphere.

Answer 2

An atmosphere is a layer of gasses that envelop an astronomical object, held in place by the gravity of the object.

Cryosphere includes the components of the Earth System at and below the land and ocean surface that are frozen, including snow cover, glaciers, ice sheets, etc.

The lithosphere is the solid, outer part of Earth. The lithosphere includes the brittle upper portion of the mantle and the crust, the outermost layers of Earth’s structure.

The biosphere is made up of the parts of Earth where life exists—all ecosystems.

A hydrosphere is the total amount of water on a planet (covers 71% of the surface of the Earth - saltwater in oceans, freshwater in ice caps, etc.). The hydrosphere includes water that is on the surface of the planet, underground, and in the air. A planet’s hydrosphere can be liquid, vapor, or ice.

Question 3

What is a dynamic equilibrium?

Answer 3

A state of balance between continuing processes, resulting in no observable change in the system.

For example, in the Earth’s atmosphere, there is a dynamic equilibrium between the amount of heat energy that is received from the Sun and the amount of heat energy radiated back into space. If these two processes are balanced, the Earth’s temperature remains stable.

Question 4

What is a feedback?

Answer 4

A change to one part of the system creates changes in another part.

Can be positive/negative.

Question 5

What is positive feedback?

Answer 5

A change is amplified as other system changes happen. For example, the melting of ice, particularly sea ice, leads to a corresponding decrease in albedo.

Positive feedback loops involve reinforcing a specific behaviour or action, leading to its amplification. Positive feedback tends to cause system instability.

Question 6

What is negative feedback?

Answer 6

A change is counteracted by other system changes. For example, if drought causes a lake to evaporate, then the lake will decrease in surface area, leading to less and less evaporation.

Negative feedback loops are important for the stabilisation of a system and ensure the maintenance of a steady, stable state.

Question 7

What is an ecosystem?

Answer 7

An ecosystem includes all the biotic interactions of a community, as well as the interactions between organisms and their abiotic environment

Question 8

Biotic / abiotic

Answer 8

Biotic - all living things e.g. animals, plants, fungi and bacteria.
Abiotic - non-living things e.g. water, soil, air, sunlight, temperature, minerals.

Question 9

What are some ecosystems around the world?

Answer 9

Tundra
Boreal forest
Grassland
Chaparral
Desert
Savannah
Lakes, Streams, Oceans

Question 10

What is environmental resistance, and what are its factors?

Answer 10

This refers to the capacity of an ecosystem to resist change despite the introduction of a stressor.

Environmental resistance protects an ecosystem by keeping it in balance. If the trophic and biological organization is disrupted by the unchecked reproduction of an invasive species, for instance, the ecosystem may collapse. Environmental resistance factors impede unchecked growth by reducing the health, survival, or reproductive rate of a population.

Environmental resistance can come from abiotic (non-living) factors or biotic (living) factors. Some examples of abiotic resistance factors are soil quality, wildfires, and drought. Some examples of biotic resistance factors are disease, predation, species diversity, and competition for food with other species.

An example of environmental resistance might include a population of rabbits in a particular neighborhood whose reproduction is controlled by recurrent droughts, predation, disease, and human activity. Environmental resistance factors work towards keeping populations within an ecosystem in check so that they do not exceed carrying capacity.

Question 11

What are the limiting factors to expansion of communities?

Answer 11

Environmental resistance can come from abiotic (non-living) factors or biotic (living) factors. Some examples of abiotic resistance factors are soil quality, wildfires, and drought. Some examples of biotic resistance factors are disease, predation, species diversity, and competition for food with other species.

Question 12

What is carrying capacity?

Answer 12

The maximum no. of individuals of a given species that a particular environment can support for an indefinite period, assuming there are no changes in the environment.

The level of carrying capacity is dynamic and dependent on both biotic and abiotic conditions, such as weather, seasons, shelter, etc.

Populations may overshoot carrying capacity for short times, before collapsing or reducing to levels below. Population density factor are what keep population sizes in check.

E.g. Earth Overshoot Day.

Question 13

What is a trophic level?

Answer 13

The position of an organism in a food web.

• Primary producer (plant/algae) is eaten by….
  – Primary consumer (herbivores) is eaten by….
  – Secondary consumer (carnivore/omnivore) is eaten by….
  – Tertiary consumer (carnivore) is decomposed by….
  – Decomposers.

Question 14

What is a trophic cascading effect?

Answer 14

• Feedback mechanism
• Indirect effects arising from alterations on one trophic level that cascades to other levels - not only the immediately affected
  level
• Can affect both biotic and abiotic factors of the ecosystem
• Can be bottom-up or top-down

Trophic cascades can in certain circumstances help to combat and mitigate the impacts of climate change by restoring healthy ecosystem services.

Question 15

What is a keystone species?

Answer 15

A keystone species is a species that exerts profound influence on a community in excess of that expected by its relative abundance

Question 16

What is overgrazing?

Answer 16

• excessive grazing which causes damage to grassland
• A biotic factor problem that becomes an abiotic factor problem - heavy grazing (exceeding the carrying capacity) leads to reduced biodiversity and reduced productivity
• Insufficient recovery time will hinder plants from re-establishing populations.
• This leads to bare soil, susceptible to erosion which degrades the land of nutrients and soil seed banks.
• Ultimately, desertification.

Question 17

What is eutrophication?

Answer 17

• the enrichment of water from inorganic plant nutrients
  (e.g. nitrogen and phosphorus)
• increases primary production
• increases decomposition
• affects oxygen levels in the water
• facilitates low visibility and light penetration due to the growth of algae and cyanobacteria
• altered species composition due to changed physical properties (e.g. differing hunting patterns)

Question 18

What are the 5 biogeochemical cycles?

Answer 18

Carbon
Nitrogen
Phosphorus
Sulfur
Hydrologic

Question 19

How does the carbon cycle work?

Answer 19

The carbon cycle describes how carbon moves between the atmosphere, soils, living creatures, the ocean, and human sources.

Carbon present in the atmosphere is absorbed by plants for photosynthesis (which uses energy from the sun to chemically combine carbon dioxide with hydogen and oxygen from water to form sugar molecules). These plants are then consumed by animals, which digest the sugar molecules, to get energy for their bodies. Respiration, excretion, and decomposition release the carbon back into the atmosphere or soil, continuing the cycle.

The ocean is a carbon sink, limestone and fossil fuels too.

Human impact: Shifting of carbon from underground deposits through combustion of fossil fuels and deforestation.
Implications? Increased CO2 in the atmosphere (from preindustrial 0,029% to 0,04%); Climate change.

Question 20

Describe the nitrogen cycle, as well as human impacts.

Answer 20

Nitrogen is the most plentiful element in Earth’s atmosphere and is a constituent of all living matter. It is essential to human survival as well as the survival of other animals and plants.

But even while surrounded by nitrogen in the atmosphere, animals and plants are unable to make use of free nitrogen, because they lack the enzymes necessary to convert it to reactive forms they can work with.

Question 21

Why protect ecosystems?

Answer 21

Ecosystems provide important benefits to human societies, termed as ‘ecosystem services’.

Ecosystem services can be clean air, clean water, carbon storage, storm protection, food, pollination, etc.

Question 22

What is environmental science?

Answer 22

The study of environmental systems, addressing environmental problems as well as human impacts on the environment.

It is an interdisciplinary field, i.e. you can have ecology, biology, etc.

Question 23

What is thermodynamics?

Answer 23

The study of energy and its transformation.

Question 24

What is energy?

Answer 24

The ability or capacity to do work, i.e. the transfer of energy to or from an object through force and movement e.g. growing, moving, reproducing, hitting a ball.

Can be measured in units of work (kilojoule), or units of heat (kilocalorie), or kWh, and found as chemical energy, radiant, solar, thermal, mechanical, nuclear, electrical.

Can be potential or kinetic. Energy associated with the motion of an object is called kinetic energy. Energy stored in an object due to its position is called potential energy.

Question 25

Do the laws of thermodynamics apply to all things in the universe?

Answer 25

Yes. Thermodynamic laws dictate that to sustain any activity without stopping, all systems (living or not) have to disperse energy.

Question 26

1st law of thermodynamics

Answer 26

• conservation of energy
• energy can neither be created nor destroyed
• it only changes it form (e.g. chemical to mechanical, mechanical to heat)

In ecosystems, this law implies that the total amount of energy remains constant as it flows through the system. Energy enters an ecosystem primarily as sunlight, which is captured by plants through photosynthesis and converted into chemical energy (in the form of glucose). This energy is then transferred through the food web from producers to consumers and decomposers. At each stage, the energy is merely transformed, not lost, though the form it takes changes (e.g., from light to chemical to heat).

Question 27

2nd law of thermodynamics

Answer 27

• When energy changes in form, it always goes from a more useful to a less useful form (more
  disorganised).
• The efficiency of the energy conversion is never 100%; heat that is released in the conversion is less useful (disorganised) energy.
• This means that the amount of useful energy available to do work decreases over time, as the disorder increases.
• Entropy is a scientific concept that is most commonly associated with a state of disorder, randomness, or uncertainty. It is irreversible.

As energy moves through an ecosystem, it becomes less available for work. At each trophic level, energy is lost as heat due to metabolic processes (e.g., respiration, movement, digestion). This explains why energy pyramids are typically narrow at the top—there is less available energy at higher trophic levels because much is lost as heat at each transfer, resulting in reduced biomass and fewer organisms at these levels.

Question 28

Where does energy in the ecosystem come from?

Answer 28

Photosynthesis produced via primary producers, which are organisms such as plants or algae that perform photosynthesis.

Cellular respiration is reversed photosynthesis - using stored energy to do work.

Question 29

What is Gross Primary Productivity?

Answer 29

The total amount of energy that primary producers in a given area capture in a given time

Question 30

What is net primary productivity, and how is it measured?

Answer 30

The amount of carbon retained in an ecosystem (increase in biomass); it is equal to the difference between the amount of carbon produced through photosynthesis (GPP) and the amount of energy that is used for respiration (R)

It is measured as grams of dry matter / metre squared / year.

Question 31

What are the factors that determine the abundance of a species in an ecosystem?

Answer 31

Abiotic factors such as access to nutrients, shelter, etc.

Biotic factors, such as primary production (i.e. storing of energy), presence of predators, population density, competition, etc.

Question 32

What are limiting nutrients?

Answer 32

The nutrient which is present in the least quantity in an ecosystem is termed a limiting nutrient in an ecosystem

E.g. phosphorus, nitrogen, iron, boron.

Limiting nutrients are essential for plant growth, can accelerate and check growth.

Question 33

What are some human activities that affect the properties of water bodies in many ways?

Answer 33

• Release of enriched sewage and inorganic nutrients, which causes eutrophication
  – Accelerated sediment pollution
  – Thermal pollution from industries (release of heated water)
  – Release of harmful substances (e.g. disease-causing agents)
  – Release of organic compounds (e.g. pharmaceuticals, pesticides,
  plastics) and inorganic compounds (e.g. heavy metals)

Question 34

Release of sewage and nutrients

Answer 34

Organic wastes increase the BOD, which is the Biological Oxygen Demand.

Decomposition of organic wastes requires oxygen, which means that excess levels of organic compounds exhaust the dissolved oxygen in the water.

BOD measures the need for oxygen to support organisms in a body of water (mg dissolved O2 / litre of water).

Fish die when oxygen levels are lower than 4mg.

Implications include anaerobic decomposition (odors and deteriorated water quality), as well as dead zones e.g. hypoxia in water.

Question 35

Sediment pollution

Answer 35

Excess runoff of sediment into the water is harmful, e.g. erosion from agriculture, logging, mining, etc.

Implications include reduced visibility due to increased turbidity, decreased light penetration leading to decreased primary production, burying of sea floor and organisms, sediments can carry toxic substances, clogging of waterways.

Question 36

Thermal pollution

Answer 36

• Comes from industries and nuclear power plants
  – Warmer water has lower capacity to hold oxygen

Implications:
– Biological stress:
– Less oxygen in water
– Affects reproductive cycles, digestion rates and respiration
– Warmer temperatures increases decomposition rates → lower
oxygen levels
– Fish need more food to maintain body weight in higher temperatures
– Less oxygen requires fish to ventilate gills more frequently

Question 37

What are the components of the atmosphere? What are the services of the atmosphere?

Answer 37

N2, O2, argon, CO2, Water vapor.

Services include: UV block, moderating climate, redistributing water

Question 38

What are the 4 layers of the atmosphere?

Answer 38

Troposphere, stratosphere, mesosphere, thermosphere

Question 39

What are the two types of pollutants released into the atmosphere?

Answer 39

Primary air pollutants (immediately released through the air e.g. through combustion)

Secondary air pollutants (formed when released substances react with substances in the air e.g. forming of ozone)

Question 40

What are nitrogen oxides?

Answer 40

Nitric oxide, nitrogen dioxide, nitrous oxide (a GHG).

Released and formed with high temperatures e.g. via combustion, transport, industry.

NOx are poisonous. Nitrous oxide can deplete stratospheric ozone.

Acid deposition (NOx reacts with water forming nitric or nitrous acid).

Question 41

What is acidification?

Answer 41

A lowering of pH of soil and water bodies.

Ecosystems can be naturally acidic but acidification can be accelerated by acid deposition from Nitrogen Oxide and Sulfur Oxide.

pH is an important factor because it determines the availability of nutrient minerals, due to their solubility. Some soil nutrients may become insoluble and thus inaccessible to plants.

Low pH increases leaching of e.g. aluminium ( Increased levels of soluble metals (e.g. Al): toxic levels-> fewer algal species-> low productivity (eventually) very clear water )

Phosphorus concentrations are reduced due to chemical binding with aluminium.

In lakes, species composition is altered at pH levels below 6. Fewer species can tolerate the lower pH levels; reproduction among especially fish is disturbed-> populations eventually collapse.

Question 42

What is a solution to increasing the pH of lakes?

Answer 42

Liming (adding of calcium carbonate)

Inefficiencies of this include mining of lime, only treats the symptoms, is done repeatedly.

Question 43

What is ozone (O3)?

Answer 43

-Great in the stratosphere, harmful in the troposphere.
-Ground-level ozone is a secondary air pollutant.
- Formed by NOx and hydrocarbons, catalysed by sunlight.
- Found in urban smog-> leads to adverse health effects, stresses plants, lowers crop yields.
- Tropospheric ozone does not replenish stratospheric ozone: stratospheric ozone is broken down by CFCs
(e.g. refrigerants– banned through the Montreal Protocol 1987). Very persistent, effects are still seen.

Question 44

What is particulate matter?

Answer 44

Released naturally or by human activities: Soot, soil particles, lead, sea salt, sulfuric acids, etc. from
combustion, industrial processes, and wear out of roads (studded tires).

Question 45

How is PM size measured?

Answer 45

Particulate matter size is measured in micrometres (µm):
PM10 =adiameter of 10 µm or less. These are inhalable;–
PM2.5 = fine particulate matter. A portion of PM10. Can transfer deep into the lungs, where
compounds can transfer to the bloodstream.
PM2,5 mobile– large transportation distances-> System boundaries are international-> UN Convention on long-range transboundary air
pollution (1979)

Question 46

What are air quality indicators?

Answer 46

Concentrations of PM10 and PM2.5 are used as air quality indicators (µm/m3 )

Question 47

What is metabolism?

Answer 47

Chemical reactions carried out in organisms (can be a response to instake of pollutants)

Question 48

What does hydrophobic mean?

Answer 48

Insoluble in water
Fears water

Question 49

Hydrophilic

Answer 49

Likes water and is soluble in water

Question 50

Lipophilic

Answer 50

Likes fat - dissolves in fats, oils, etc.

Question 51

Lipophobic

Answer 51

Does not like fat

Question 52

What do we use industrial chemicals for?

Answer 52

• Agriculture
• Cleaning / detergents
• Electronics
• Batteries
• PFAS - Per- and polyfluoroalkyl
  substances

Question 53

What is the relationship between chemicals and humans?

Answer 53

• Many of these chemicals are central for addressing other sustainability challenges, both
  environmental and social (electrification, famine, fighting decease, etc.)
  – Release of chemical compounds come with many unknowns and potentially detrimental
  effects to ecosystems and humans
  – Novel entities: the presence in nature of some compounds has been relatively short, and
  responses in terms of evolution of protective responses are still rather scarce

Question 54

What is normal and what is novel?

Answer 54

Man-made chemical compounds: did not exist in nature before mankind
→ any detectable level is abnormal
– E.g. pesticides
– PFAS

Naturally occurring compounds: background levels vary with time and location
– E.g. metals, SO2, NOx , PAH
– Levels are increased by human activities

Question 55

What is ecotoxicology?

Answer 55

“the study of harmful effects of chemicals upon ecosystems and includes effects upon individuals as well
as consequent effects at the levels of population and above”.

Deals with movement of pollutants in: * air, water, soils, sediments * food chains * chemical
transformation and biotransformation.

Question 56

Provide me with a graph of how pollutants travel in the environment through to ecosystems.

Answer 56

• Pollutant
• Biochemical changes
• Physiological changes
• Whole organism responses
• Population changes
• Community composition
• Ecosystems

Linear would be :
- Response time
- Difficulty of linking to specific pollutant
- Importance

Question 57

How can pollutants be transported?

Answer 57

Via air, organisms, water or soil.

Range depends on:– molecular size and properties;– Hydrophilicity, lipophilicity (e.g. gaseous
pollutants may transport longer than
particles or droplets in the air);– abiotic factors;– Water currents, wind, temperature, etc.

Question 58

How are pollutants taken up by organisms?

Answer 58

Ingestion, Inhalation, absorption

Question 59

What is artificial fill?

Answer 59

Original ground surface is covered by foreign material such as construction waste.

Has been used for filling in port areas of larger cities e.g. Malmo.

Question 60

What happens when local pollution is no longer local?

Answer 60

PBT - Persistent Bioaccumulative Toxic.

vPvBvT - otherwise.

Question 61

What is persistence?

Answer 61

Persistence; The resistance to being degraded by organisms or in the environment.

• Favoured by low temperatures (slower volatilization/biotransformation/chemical breakdown);–
• Allows substances to remain in the environment for extensive times;
• Allows an extended spreading of substances via air and water, beyond point of emission;
• Biological/degradation half-life: time it takes for concentration of substance to decrease by 50%

Question 62

What is the criteria for identifying persistent substances under EU Regulation REACH (EC) No 1907/2006?

Answer 62

Degradation half-life, with temperature thresholds and day thresholds.

Question 63

What is bioaccumulation?

Answer 63

The process through which substances are stored within organisms, leading to higher
concentration than what is found in the environment. The relationship between intake and
excretion/metabolization.

• Lipophilic substances are more bio-accumulated as they are stored in fatty tissues of organisms;
• Hydrophilic substances are water soluble and more readily excreted. Metabolization in terrestrial
  vertebrates often involves increasing the polarity of substances to make them more hydrophilic. If
  the substance is resistant to metabolization/detoxification it is more likely to be stored;
• Substances may be transferred to offspring via placenta or milk.

Bioaccumulation leads to biomagnification.

Question 64

What is biomagnification?

Answer 64

where concentrations of a substance increase further up in
the trophic levels– organisms at higher trophic levels may experience more toxic effects.

Question 65

What is toxicity?

Answer 65

The large variation on reactions to chemicals between species and individuals, and between
different strains of the same species due to evolving resistance.

• Effect of toxins depends on the route of uptake (e.g. ingestion faster than application on skin);
• “The dose makes the poison”– some compounds are essential for life, but become toxic at too
  high concentrations (e.g. selenium);
• The metabolism of a compound may lead to formation of metabolites that are more toxic or
  harmful than the parent compound (e.g methanol oxidised to formaldehyde, which oxidises to
  formic acid. These cause blindness, respiratory failure, and death)

Question 66

What are further complications of toxicity?

Answer 66

Further complications
★ Potentiation/synergism = when the toxicity of two or more chemicals are larger than the parts;
★ Antagonism = the sum is lesser than the parts;
★ Cocktails of chemicals may lead to activation or deactivation of other harmful substances, when
organisms are exposed to them simultaneously; Thus the relationship between the dose and toxic effect of each chemical in the cocktail

Question 67

What is an example of potentiation?

Answer 67

Example of potentiation
What happens if chemical A changes the metabolism of chemical B?

1. A inhibits the enzyme system that detoxifies B.
   → B is not detoxified as quickly, and toxic effects may be seen on the organism
2. A induces an enzyme system that activates B.
   → B gets activated more quickly, e.g. by generating highly reactive
   metabolites that damage the cells.

BUT! activation may also activate other enzymes that have a detoxifying
function that compensate for increased activation – very complex!

Question 68

Delay of toxic effects (case study)

Answer 68

Toxic effects on organisms may be delayed->
Case study: Netherlands, 1960s female eider ducks died from dieldrin (a pesticide) poisoning during the
breeding season whereas males did not. Toxic substances may be stored in fat depots: if the food supply is
good then fat depots are built up; when food is scarce/during illness/egg laying/migration, fat depots are
used for energy. Toxic substances are released into the bloodstream and potentially become activated.
This is seen among all ecosystems-> species (top predators) top of the food web most at risk.

Question 69

What are the endpoints for toxicity testing and assessment?

Answer 69

Death,

Biochemical - beneficial or detrimental responses in organisms

Physiological - effects may be seen on cellular or organ levels e.g. cardiovascular effects

Reproductive - egg shell thinning, sterility, etc.

Behavioural - disturbances in foraging or vigilance.

Question 70

What are POPs?

Answer 70

Persistent Organic Pollutants.

POPs are created by mankind both intentionally and unintentionally in industrial processes. They are long
lived and may be toxic.

Organic compunds:
* Contain carbon
* Have a high variety of molecular structures
* Chemical properties and behavior depend on size, shape, and structure

Question 71

What are the dirty dozen?

Answer 71

Some examples (the dirty dozen):
Pesticides: aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, hexachlorobenzene, mirex,
toxaphene;–
Industrial chemicals: hexachlorobenzene, polychlorinated biphenyls (PCBs);
By-products: hexachlorobenzene; polychlorinated dibenzo-p-dioxins, polychlorinated
dibenzofurans (PCDD/PCDF), and PCBs.

Question 72

What is PBT-M?

Answer 72

Persistence– Resistance to degradation in the environment.
Bioaccumulative– Organisms storing substances as intake->
excretion/metabolization,
Toxic– detrimental effects on organisms from a substance
differs between individuals and species.
Mobile– transportation potential. Often seen as readiness to
move in aquatic environments. Mobile substances are often
polar (having an electrical charge)-> water soluble

Question 73

Why do chemical substances not effect ecosystems in the same way?

Answer 73

Chemical substances do not affect ecosystems in the same
way. Effects depend on:– Chemical properties (PBT);– The quantities produced and released.

Question 74

What are other affects from chemicals and man-made products?

Answer 74

Plastics, increasing problem for living organisms: Entanglement; Ingestion; Microplastics;
Radioactive isotopes: Radon gas; Nuclear catastrophes;
Altered albedo from black carbon particles.
Risk of erosion of social resilience and loss of knowledge and traditions (e.g. traditional pest control vs.
use of pesticides).

Question 75

How did DDT end up in Antarctica?

Answer 75

DDT, along with a lot of other of these organic contaminants, actually travel through the atmosphere, toward the polar regions by a process of evaporation and then condensation in cooler climates.

Settles within penguin fat and eggs.

Question 76

How do human activities affect global systems?

Answer 76

Earth consists of many physical and biological systems. Its abundant resource have allowed many forms of life to thrive and evolve. Humans through our growing population and technology, have exploited these resources to the point that we are putting the environment at risk.

Question 77

Describe the factors that characterize human development and how they impact the environment and sustainability.

Answer 77

• Human development is typically characterized by factors associated with wealtH
• such highly developed countries have represented less than 20% of the global population but account for more than 50% of resource use - Historically, Less developed countries (LDCs) are developing countries with high poverty rates, low levels of industrialization, high fertility rates, high infant mortality rates, and very low per capita incomes (relative to highly developed countries).
• Increasingly, many of the world’s countries, such as China and India, have mixed development, with some urban residents owning considerable wealth but other urban and most rural residents living in poverty.

Question 78

What are renewable vs non-renewable resources?

Answer 78

Renewable resources are those that nature replaces fairly rapidly (on a scale of days to centuries), and can be used forever as long as they are not overexploited in the short term. E.g. sun, wind, water.

Nonrenewable resources are present in limited supplies and are depleted by use. E.g. coal, oil, natural gas.

Question 79

Explain the impact of population and affluence on consumption.

Answer 79

As population increases, people can exceed the capacity of a region to support basic needs for food, shelter, and clean water. When consumption by individuals substantially exceeds these basic needs, the resources in a region will be exceeded even more quickly. In either case, consumption that exhausts both non-renewable and renewable resources is unsustainable.

Question 80

What is ecological footprint?

Answer 80

An individual’s ecological footprint is the amount of productive land, fresh water, and ocean required on a continuous basis to supply that person with food, energy, water, housing, material goods, transportation, and waste disposal.

Question 81

Describe the three most important factors that determine human impact on the environment.

Answer 81

• Number of people (P)
• Affluence per person (A) - measure of the consumption or amount of resources used per person
• Environmental effect of the technology used to obtain and consume those resources (T)

Equation is Impact = P x A x T

Question 82

What is sustainability?

Answer 82

Sustainability is the ability to meet current human natural resource needs without compromising the ability of future generations to meet their needs; in other words, it is the ability of humans to manage natural resources indefinitely without the environment going into a decline from the stresses imposed by human society on the natural systems that maintain life.

Question 83

Tragedy of the commons by Garrett Hardin

Answer 83

Garrett Hardin contended that our inability to solve many environmental problems is the result of a struggle between short‐term individual welfare and long‐term environmental sustainability and societal welfare.

Question 84

What are common pool resources?

Answer 84

Common‐pool resources are those parts of our environment that are available to everyone but for which no single individual has responsibility—shared resources such as the atmosphere, fresh water, forests, wildlife, and ocean fisheries.

Question 85

What is sustainable development?

Answer 85

Sustainable development is economic development that meets the needs of the present generation without compromising the ability of future generations to meet their own needs.

Three factors—environmentally sound decisions, economically viable decisions, and socially equitable decisions—interact to promote sustainable development.

Question 86

What is environmental science?

Answer 86

the interdisciplinary study of humanity’s relationship with other organisms and the nonliving physical environment.

Question 87

What are systems?

Answer 87

each system is a set of components that interact and function as a whole

At a global level are Earth systems, which include Earth’s climate, atmosphere, land, coastal zones, and the ocean.

Question 88

What is the scientific method?

Answer 88

The scientific method is the way a scientist approaches a problem by formulating a hypothesis and then testing it by means of an experiment.

Question 89

What are the steps in a scientific method?

Answer 89

State the problem or unanswered question; develop a hypothesis; design and perform an experiment to test the hypothesis; analyze and interpret the data; and share the conclusion with others.

Question 90

What are the five stages of addressing environmental problems?

Answer 90

1. Scientific assessment involves gathering information about a potential environmental problem.
2. Risk analysis evaluates the potential effects of intervention.
3. Public education and involvement occur when the results of scientific assessment and risk analysis are placed in the public arena.
4. Political action is the implementation of a particular course of action by elected or appointed officials.
5. Long‐term evaluation monitors the effects of the action taken.

Question 91

Briefly describe the history of Lake Washington pollution in the 1950s.

Answer 91

Lake Washington exemplifies a successful approach to addressing a relatively simple environmental problem. The pouring of treated sewage into Lake Washington had raised its level of nutrients to the point where the lake supported excessive growth of cyanobacteria. Disposal of the sewage in another way solved the lake’s pollution problem.

Question 92

What is ecology?

Answer 92

Ecology is the study of interactions among organisms and between organisms and their biotic environment

Question 93

Distinguish among the following ecological levels: population, community, ecosystem, landscape, and biosphere

Answer 93

A population is a group of organisms of the same species that live in the same area at the same time.

A community is a natural association that consists of all the populations of different species that live and interact within an area at the same time.

An ecosystem is a community and its physical environment. A landscape is a region that includes several interacting ecosystems.

The biosphere is the parts of Earth’s atmosphere, ocean, land surface, and soil that contain all living organisms.

Question 94

What is energy?

Answer 94

Energy is the capacity to do work. Energy can be transformed from one form to another but is often measured as heat; the unit of heat is the kilocalorie (kcal).

Question 95

Potential vs kinetic energy

Answer 95

Potential energy is stored energy; kinetic energy is energy of motion. Using a bow and arrow as an example, potential energy is stored in the drawn bow and is converted to kinetic energy as the string is released and the arrow speeds toward its target.

Question 96

What does a system refer to in thermodynamics?

Answer 96

system refers to a group of atoms, molecules, or objects being studied; the rest of the universe other than the system is known as the surroundings.

Question 97

Distinguish between open and closed systems

Answer 97

A closed system is self‐contained; that is, it does not exchange energy with its surroundings.

In contrast, an open system exchanges energy with its surroundings.

Question 98

State the first and second laws of thermodynamics, discussing the implications of these laws as they relate to organisms.

Answer 98

According to the first law of thermodynamics, energy cannot be created or destroyed, although it can change from one form to another.

According to the second law of thermodynamics, when energy is converted from one form to another, some of it is degraded into heat, a less usable form that disperses into the environment. The first law explains why organisms cannot produce energy but must continuously capture it from the surroundings. The second law explains why no process requiring energy is ever 100% efficient.

Question 99

Summarize the reactions for photosynthesis and cellular respiration, contrasting these two biological processes.

Answer 99

Plants, algae, and some bacteria capture radiant energy during phototsyntehsis and incorporate some of it into chemical energy contained within carbohydrate molecules. All organisms obtain the energy in carbohydrates and other molecules by cellular respiration , in which molecules such as glucose are broken down, releasing energy.

Question 100

What is a trophic level?

Answer 100

A trophic level is an organism’s position in a food chain, which is determined by its feeding relationships. A food web is a representation of the interlocking food chains that connect all organisms in an ecosystem.

Question 100

Why is photosynthesis important?

Answer 100

Photosynthesis is essential to all life on earth; both plants and animals depend on it. It is the only biological process that can capture energy that originates in outer space (sunlight) and convert it into chemical compounds (carbohydrates) that every organism uses to power its metabolism.

Question 100

What are producers, consumers and decomposers?

Answer 100

Producers are the photosynthetic organisms (plants, algae, and some bacteria) that are potential food resources for other organisms. Consumers, which feed on other organisms, are almost exclusively animals. Decomposers feed on the components of dead organisms and organic wastes, degrading them into simple inorganic materials that producers can then use to manufacture more organic material.

Question 101

What is energy flow?

Answer 101

Energy flow is the passage of energy in a one‐way direction through an ecosystem. Energy flow through an ecosystem is linear, from the sun to producer to consumer to decomposer.

Question 102

Describe typical pyramids of numbers, biomass, and energy.

Answer 102

A pyramid of numbers shows the number of organisms at each successive trophic level.

A pyramid of biomass illustrates the total biomass at each successive trophic level.

A pyramid of energy illustrates the energy content of the biomass of each trophic level.

Question 103

What is biomass?

Answer 103

Biomass is a quantitative estimate of the total mass, or amount, of living material; it indicates the amount of fixed energy at a particular time.

Question 104

Distinguish between gross primary productivity and net primary productivity, discussing human impact on the latter.

Answer 104

Gross primary productivity (GPP) is the total amount of photosynthetic energy that plants capture and assimilate in a given period. Net primary productivity (NPP) is productivity after respiration losses are subtracted. Scientists have estimated that as much as 32% of the global NPP is appropriated for the human economy. Human use of global productivity is competing with other species’ energy needs.

Question 105

How does the carbon cycle work?

Answer 105

In the carbon cycle, carbon enters plants, algae, and cyanobacteria as carbon dioxide (CO2), which is incorporated into organic molecules by photosynthesis. Cellular respiration by plants, by animals that eat plants, and by decomposers returns CO2 to the atmosphere, making it available for producers again. Combustion and weathering also return CO2 to the atmosphere.

Question 106

Nitrogen cycle

Answer 106

In the nitrogen cycle, nitrogen fixation is the conversion of nitrogen gas to ammonia. Nitrification is the conversion of ammonia or ammonium to nitrate. Assimilation is the biological conversion of nitrates, ammonia, or ammonium into nitrogen‐containing compounds by plants; the conversion of plant proteins into animal proteins is also part of assimilation. Ammonification is the conversion of organic nitrogen to ammonia and ammonium ions. Denitrification converts nitrate to nitrogen gas.

Question 107

Phosphorus cycle

Answer 107

The phosphorus cycle has no biologically important gaseous compounds. Phosphorus erodes from rock as inorganic phosphates, and plants absorb it from the soil. Animals obtain phosphorus from their diets, and decomposers release inorganic phosphate into the environment.

Question 108

Sulfur cycle

Answer 108

In the sulfur cycle, most sulfur occurs as rocks or as sulfur dissolved in the ocean. Sulfur‐containing gases, which include hydrogen sulfide, sulfur oxides, and dimethyl sulfide (DMS), comprise a minor part of the atmosphere and are not long‐ lived. A tiny fraction of sulfur is present in the proteins of living organisms. Bacteria drive the sulfur cycle.

Question 109

Hydrologic cycle

Answer 109

The hydrologic cycle, which continuously renews the supply of water essential to life, involves an exchange of water among the land, the atmosphere, and organisms. Water enters the atmosphere by evaporation and transpiration and leaves the atmosphere as precipitation. On land, water runs off to lakes, rivers, and the ocean or filters through the ground. Groundwater is stored in underground caverns and porous layers of rock.

Question 110

Summarize the effects of solar energy on Earth’s temperature, including the influence of albedos of various surfaces.

Answer 110

Of the solar energy that reaches Earth, 30% is immediately reflected away and the remaining 70% is absorbed.

Albedo is the proportional reflectance of solar energy from Earth’s surface, commonly expressed as a percentage. Glaciers and ice sheets have high albedos, and the ocean and forests have low albedos.

Ultimately, all absorbed solar energy is radiated into space as infrared (heat) radiation. A combination of Earth’s roughly spherical shape and the tilt of its axis concentrates solar energy at the equator and dilutes solar energy at higher latitudes.

Question 111

Describe the four layers of Earth’s atmosphere: troposphere, stratosphere, mesosphere, and thermosphere.

Answer 111

The troposphere is the layer of the atmosphere closest to Earth’s surface; weather occurs in the troposphere. The stratosphere, found directly above the troposphere, contains a layer of ozone that absorbs much of the sun’s damaging ultraviolet radiation. The mesosphere, found directly above the stratosphere, has the lowest temperatures in the atmosphere. The thermosphere has steadily rising temperatures because the air molecules there absorb high‐energy X‐rays and short‐wave ultraviolet radiation.

Question 112

Discuss the roles of solar energy and the Coriolis effect in producing atmospheric circulation.

Answer 112

Variations in the amount of solar energy reaching different places on Earth largely drive atmospheric circulation. Atmospheric heat transfer from the equator to the poles produces a movement of warm air toward the poles and a movement of cool air toward the equator, moderating the climate. The atmosphere also exhibits winds, complex horizontal movements that result in part from differences in atmospheric pressure and from the Coriolis effect.

Question 113

Coriolis effect

Answer 113

The Coriolis effect is the influence of Earth’s rotation, which tends to deflect fluids (air and water) toward the right in the Northern Hemisphere and toward the left in the Southern Hemisphere.

Question 114

Discuss the roles of solar energy and the Coriolis effect in producing global water flow patterns, including gyres.

Answer 114

Surface‐ocean currents result largely from prevailing winds, which, in turn, are generated from solar energy. Other factors that contribute to ocean currents include the Coriolis effect, the position of landmasses, and the varying density of water. Gyres are large, circular ocean current systems that often encompass an entire ocean basin. Deep‐ocean currents often travel in different directions and at different speeds than do surface currents. The present circulation of shallow and deep currents, known informally as the ocean conveyor belt, affects regional and possibly global climate.

Question 115

Describe El Niño–Southern Oscillation (ENSO) and La Niña and some of their effects.

Answer 115

El Niño–Southern Oscillation (ENSO) is a periodic, large‐scale warming of surface water of the tropical eastern Pacific Ocean that affects both ocean and atmospheric circulation patterns. ENSO results in unusual weather in areas far from the tropical Pacific.

During a La Niña event, surface water in the eastern Pacific becomes unusually cool.

Question 116

Distinguish between weather and climate, briefly discussing regional precipitation differences.

Answer 116

Weather refers to the conditions in the atmosphere at a given place and time, whereas climate refers to the typical patterns of weather conditions that occur in a place over a period of years.

Temperature and precipitation largely determine an area’s climate. Precipitation is greatest where warm air passes over the ocean, absorbing moisture, and is then cooled, such as when mountains force humid air upward.

Question 117

Contrast tornadoes and tropical cyclones

Answer 117

A tornado is a powerful, rotating funnel of air associated with severe thunderstorms. A tropical cyclone is a giant, rotating tropical storm with high winds.

Tropical cyclones are called hurricanes in the Atlantic, typhoons in the Pacific, and cyclones in the Indian Ocean.

Question 118

Define plate tectonics, explaining its relationship to earthquakes and volcanic eruptions.

Answer 118

Plate tectonics is the study of the processes by which the lithospheric plates move over the asthenosphere. Earth’s lithosphere (outermost rock layer) consists of seven large plates and a few smaller ones.

As the plates move horizontally, the continents change their relative positions. Plate boundaries are sites of intense geologic activity, such as mountain building, volcanoes, and earthquakes.

Question 119

What is evolution?

Answer 119

Evolution = cumulative genetic changes that occur over time in a population of organisms; evolution explains many patterns observed in the natural world

Question 120

What is natural selection?

Answer 120

Natural selection = process in which better‐adapted individuals—those with a combination of genetic traits better suited to environmental conditions—are more likely to survive and reproduce, increasing their proportion in the population.

Question 121

Explain the four premises of evolution by the natural selection as proposed by the Charles Darwin

Answer 121

1. Each species produces more offspring than will survive to maturity.
2. The individuals in a population exhibit heritable variation in their traits.
3. Organisms compete with one another for the resources needed to survive.
4. Those individuals with the most favorable combination of traits are most likely to survive and reproduce, passing their genetic characters on to the next generation.

Question 122

Identify the major groups of living organisms.

Answer 122

Organisms are classified into six major groups: bacteria, archaea, protists (algae, protozoa, slime molds, water molds), plants, fungi (yeasts and mushrooms and some molds), and animals.

Question 123

Explain the four factors that produce changes in population size.

Answer 123

A population is a group of individuals of the same species that live in the same geographic area at the same time.

Growth rate (r) is the rate of change of a population’s size, expressed in percent per year.

On a global scale (when dispersal is not a factor), growth rate (r) is due to birth rate (v) and death rate (d): r = b − d.

Emigration (e), the number of individuals leaving an area, and immigration (i), the number of individuals entering an area, affect a local population’s size and growth rate.

For a local population (where dispersal is a factor), r = (b − d) + (i − e).

Question 124

Use intrinsic rate of increase, exponential population growth, and carrying capacity to explain the differences between J‐shaped and S‐shaped growth curves.

Answer 124

Intrinsic rate of increase is the exponential growth of a population that occurs under ideal conditions.

Exponential population growth is the accelerating population growth that occurs when optimal conditions allow a constant reproductive rate over a period of time.

The carrying capacity (K) is the maximum number of individuals of a given species that a particular environment can support for an indefinite period, assuming there are no changes in the environment.

Although populations with a constant reproductive rate exhibit exponential population growth for limited periods (the J curve), eventually the growth rate decreases to around zero or becomes negative. The S curve shows an initial lag phase (when the population is small), followed by an exponential phase, followed by a leveling phase as the carrying capacity of the environment is reached.

Question 125

Distinguish between density‐dependent and density‐independent factors that affect population size.

Answer 125

A density‐dependent factor is an environmental factor whose effects on a population change as population density changes.

A density‐independent factor is an environmental factor that affects the size of a population but is not influenced by changes in population density. Hurricanes and fires are examples.

Question 126

Describe type I, type II, and type III survivorship curves.

Answer 126

Survivorship is the probability that a given individual in a population will survive to a particular age. There are three general types of survivorship curves. In type I survivorship, death is greatest in old age. In type III survivorship, death is greatest among the young. In type II survivorship, death is spread evenly across all age groups.

Question 127

Define metapopulation, distinguishing between source habitats and sink habitats.

Answer 127

Many species exist as a metapopulation, a set of local populations among which individuals are distributed in distinct habitat patches across a landscape.

Source habitats are preferred sites where local reproductive success is greater than local mortality. Sink habitats are lower‐quality habitats where individuals may suffer death or, if they survive, poor reproductive success.

Question 128

Describe the factors that contribute to an organism’s ecological niche.

Answer 128

The ecological niche is the organism’s place and role in a complex biotic and abiotic system.

An organism’s ecological niche is the totality of its adaptations, its use of resources, and the lifestyle to which it is fitted

Question 129

Define competition and relate the concepts of competitive exclusion and resource partitioning.

Answer 129

Competition is the interaction among organisms that vie for the same resources (such as food or living space) in an ecosystem.

Many ecologists think two species cannot occupy the same niche in the same community for an indefinite period. In competitive exclusion, one species excludes another as a result of competition for limited resources. Some species reduce competition by resource partitioning, in which they use resources differently.

Question 130

Define symbiosis, and distinguish among mutualism, commensalism, and parasitism.

Answer 130

Symbiosis is any intimate relationship or association between members of two or more species. Mutualism is a symbiotic relationship in which both partners benefit. Commensalism is a type of symbiosis in which one organism benefits and the other one is neither harmed nor helped. Parasitism is a symbiotic relationship in which one organism benefits and the other is adversely affected.

Question 131

Define predation, and describe the effects of natural selection on predator–prey relationships.

Answer 131

Predation is the consumption of one species (the prey) by another (the predator). During coevolution between predator and prey, the predator evolves more efficient ways to catch prey, and the prey evolves better ways to escape the predator.

Question 132

Define keystone species, and discuss the wolf as a keystone species.

Answer 132

A keystone species is a species, often a predator, that exerts a profound influence on a community in excess of that expected by its relative abundance. One example of a keystone species is the gray wolf. Where wolves were hunted to extinction, the populations of deer, elk, and other herbivores increased. As these herbivores overgrazed the vegetation, many plant species disappeared. Many smaller animals such as insects and trout decreased because the plants they depended on for food were now less abundant. Thus, the disappearance of the wolf resulted in an ecosystem with considerably less biological diversity.

Question 133

Describe factors associated with high species richness.

Answer 133

Species richness, the number of species in a community, is often great when there are many potential ecological niches, when the area is at the margins of adjacent communities, when the community is not isolated or severely stressed, when one species does not dominate others, and when communities have a long geologic history.

Question 134

Define ecological succession, and distinguish between primary and secondary succession.

Answer 134

Ecological succession is the orderly replacement of one community by another. Primary succession is the change in species composition over time in a previously uninhabited environment. Secondary succession is the change in species composition that takes place after some disturbance destroys the existing vegetation; soil is already present.

Question 135

What is the PB concept?

Answer 135

The planetary boundaries framework defines a “safe operating space” for humanity based on Earth’s biophysical processes.

It aims to avoid abrupt, potentially catastrophic environmental change at a global scale by not crossing key thresholds

Question 136

Identified PB boundaries in 2009 paper.

Answer 136

The authors identify nine planetary boundaries, seven of which have quantifiable thresholds: climate change, ocean acidification, stratospheric ozone depletion, biogeochemical flows of nitrogen and phosphorus, global freshwater use, land system change, and biodiversity loss. Two remain unquantified: chemical pollution and atmospheric aerosol loading.

Question 137

How many boundaries have been transgressed?

Answer 137

Except for stratospheric ozone depletion, atmospheric aerosol loading and ocean acidification, seven out of eight globally quantified ESBs have already been transgressed. Many regional boundaries, especially in more than half of the global land area, have also been exceeded

Question 138

Describe the climate change boundary

Answer 138

The threshold for CO₂ concentrations is set at 350 ppm, and radiative forcing should not exceed +1 W/m² above pre-industrial levels. Current levels are already beyond this, pushing the planet toward dangerous climate shifts.

The ESB for climate change suggests that global warming beyond 1.0°C (already exceeded) risks triggering dangerous tipping points, such as the collapse of the Greenland ice sheet. Limiting warming to 1.5°C is necessary to avoid severe impacts

Question 139

Biodiversity loss PB

Answer 139

The boundary for biodiversity is set at an extinction rate of fewer than 10 species per million per year. Current rates are much higher, indicating a significant breach.

Question 140

Biogeochemical N cycle

Answer 140

Human activities now convert more nitrogen (N) from the atmosphere into reactive forms than the Earth’s natural processes. The limit is set to 35 Tg N/year to avoid ecosystem disruptions like waterway eutrophication and atmospheric pollution.

Question 141

Freshwater use

Answer 141

Global freshwater use is limited to 4,000 km³ per year. Exceeding this could disrupt the water cycle and harm ecosystems, particularly through impacts on monsoon patterns and freshwater ecosystems.

Question 142

Interconnectedness of PB

Answer 142

Transgressing one boundary may shift others or create feedback loops, amplifying risks. For instance, changes in biodiversity can affect the resilience of ecosystems, influencing climate change and water cycles.

Question 143

Governance implications of PBs

Answer 143

The concept of planetary boundaries suggests a shift from minimizing negative externalities to managing human development within safe planetary limits, promoting sustainability and resilience.

Question 144

Thresholds vs tipping points

Answer 144

In complex systems, thresholds are a major reason for nonlinear behaviour. A tipping point has a similar meaning but is more related to systems: signifying a critical point after which the system shifts radically and potentially irreversibly into a different equilibrium state.

Question 145

What is unique about the holocene?

Answer 145

In geological history, the Earth has undergone significant changes, labelling as epochs. One where Earth later stabilises and this allows civilization and the life as we know it today is called Holocene epoch. This epoch is the only time in geological history that has evidence of sustaining humans on earth. The human impact on modern-era Earth and its ecosystems may be considered of global significance for the future evolution of living species. The PB are set as a safe zone for human operation that will keep the planet on a Holocene like state, It is the reference used to set most of the boundaries as the uncertainties are more controllable based on the evidence we have from the Holocene state.

Question 146

What are the core boundaries?

Answer 146

Climate change and biosphere integrity (formerly biodiversity loss) are identified as the two “core” planetary boundaries due to their fundamental role in regulating Earth’s system. Crossing these boundaries has the potential to drive the Earth into a new, less hospitable state.

Question 147

Two-tiered approach

Answer 147

For some boundaries, such as biosphere integrity and land-system change, a two-tiered approach is adopted. It recognizes regional-level thresholds that aggregate into global impacts, allowing for a more nuanced understanding of how local changes affect the planet as a whole.

Question 148

Precautionary principle

Answer 148

The paper emphasizes the importance of setting boundaries upstream of potential tipping points, allowing a buffer for uncertainty and early warning signals. This precautionary approach helps ensure that humanity avoids pushing Earth’s systems too far.

Question 149

Proposed ESBs

Answer 149

ey ESBs are proposed for different Earth system processes, including:

Climate: Global warming should be limited to 1.0°C to 1.5°C to avoid triggering climate tipping points.

Biosphere: At least 50-60% of the Earth’s land surface should remain as natural ecosystems to maintain life-support functions.

Water: Surface water flows should not be altered by more than 20% from natural flows to protect freshwater ecosystems.

Nitrogen and Phosphorus Cycles: Nitrogen and phosphorus inputs into ecosystems should remain below levels that cause eutrophication and ecosystem collapse.

Question 150

Two components of freshwater change

Answer 150

• Blue water, which is freshwater that is available on the land surface i.e. in rivers, streams, lakes, including ice caps and glaciers.
• Green water, water available on the soil (soil moisture) and groundwater.

The PB for blue water include the activities of altering water streams i.e. building of dams and excessive use of freshwater from river posing threat to the reduction of available freshwater.

For green water, excessive pumping of groundwater is one example of the case that may lead to ground sinking and reduced soil moisture, with effect on agriculture activities.

Question 151

The two components of biogeochemical flows, as defined in the planetary boundaries framework, are nitrogen (N) and phosphorus (P) cycles. Here’s a brief explanation of each:

Answer 151

1. Nitrogen (N) Cycle:
   
   • Human activities, particularly industrial and agricultural practices, have dramatically increased the conversion of nitrogen from its inert form in the atmosphere into reactive forms, primarily through the use of synthetic fertilizers. Excess nitrogen enters ecosystems through runoff, causing problems like eutrophication (excessive nutrient loading in water bodies), which leads to algal blooms, dead zones, and biodiversity loss. The planetary boundary for nitrogen aims to limit the amount of nitrogen that humans add to ecosystems to avoid these disruptions.
2. Phosphorus (P) Cycle:
   
   • Like nitrogen, phosphorus is a crucial nutrient for plant growth, and it is heavily used in fertilizers. However, phosphorus is mined from finite geological deposits and, once applied to land, much of it runs off into freshwater systems. Excess phosphorus causes similar problems to nitrogen, such as eutrophication in lakes and coastal waters. The phosphorus boundary focuses on controlling the amount of phosphorus that enters water systems to prevent ecological damage and protect water quality.

Both nitrogen and phosphorus are essential for life but, when used excessively, they destabilize ecosystems, leading to long-term environmental harm. Managing these biogeochemical flows within safe limits is key to sustaining ecosystem health.

Question 152

Biosphere integrity is divided into two key components: genetic diversity and functional diversity. Here’s a brief explanation of each:

Answer 152

Genetic Diversity:

Genetic diversity refers to the variety of genes within species, which is essential for populations to adapt to environmental changes and maintain long-term resilience. Loss of genetic diversity can result from habitat destruction, over-exploitation, and pollution, leading to a higher risk of species extinction and reduced ecosystem health. The planetary boundary for genetic diversity is often measured by the rate of species extinctions. A safe threshold is set to maintain ecosystem services, and transgressing this boundary can destabilize ecosystems and reduce their ability to support life, including human well-being.
Functional Diversity:

Functional diversity refers to the range of different biological functions and processes performed by species within an ecosystem. It reflects the roles species play in ecosystem functioning, such as nutrient cycling, pollination, and carbon storage. When functional diversity is reduced—either through species loss or the degradation of ecosystems—key ecosystem services are compromised. This can lead to reduced ecosystem resilience, making them less capable of withstanding environmental shocks and stresses (e.g., climate change, deforestation). Maintaining functional diversity ensures ecosystems can continue providing essential services that support all forms of life.

Both genetic and functional diversity are essential for the stability and resilience of ecosystems, making them critical to maintaining the overall health of the biosphere. The planetary boundary framework emphasizes the importance of protecting both to prevent irreversible damage to Earth’s ecosystems.

Question 153

Describe 3 consequences of climate change that also relate to another PB.

Answer 153

Loss of Biodiversity (Biosphere Integrity):

Climate change exacerbates habitat destruction and alters ecosystems, driving species extinction and reducing genetic diversity, which are key aspects of biosphere integrity. Rising temperatures, shifting weather patterns, and extreme events disrupt ecosystems, pushing species beyond their adaptive limits. This impacts biodiversity by reducing both genetic and functional diversity, leading to ecosystem degradation and loss of resilience.

Ocean Acidification:

Climate change increases the concentration of carbon dioxide (CO₂) in the atmosphere, which is absorbed by oceans, causing ocean acidification. This reduces the pH levels of seawater, harming marine ecosystems, especially organisms that rely on calcium carbonate (e.g., coral reefs, shellfish). Ocean acidification is a direct consequence of climate change but is also recognized as a separate PB due to its significant and distinct impacts on marine biodiversity and ecosystem services.

Disruption of the Water Cycle (Freshwater Use):

Climate change intensifies the global water cycle, causing more extreme weather events, including floods, droughts, and changes in precipitation patterns. This alters the availability and distribution of freshwater, putting stress on freshwater ecosystems. As climate change accelerates, it exacerbates overuse of water resources, leading to the transgression of the freshwater use boundary, which is critical for maintaining both ecosystem services and human needs.

Question 154

Consequences of Land-System Change on Biosphere Integrity:

Answer 154

Land-system change, particularly through deforestation, agricultural expansion, and urbanization, leads to habitat destruction, contributing directly to the loss of genetic diversity and functional diversity within ecosystems. This degradation of habitats reduces the ability of species to survive, contributing to biodiversity loss and undermining ecosystem services.

The fragmentation of ecosystems due to land-use change also limits species’ ability to migrate in response to climate change, further exacerbating the loss of biodiversity.

Question 155

Consequences of Biogeochemical Flows on Freshwater Systems:

Answer 155

Excess nitrogen and phosphorus from fertilizers run off into rivers, lakes, and oceans, causing eutrophication, where excessive nutrient levels lead to algal blooms. These blooms deplete oxygen levels in water bodies, creating “dead zones” where aquatic life cannot survive, undermining freshwater use and ecosystem health.

The contamination of freshwater systems through nutrient runoff also directly impacts the availability of clean water for human use, affecting drinking water supplies and agriculture.

Question 156

Consequences of Aerosols on Climate Change:

Answer 156

Aerosols, both reflective and absorbing, have complex effects on climate change. Reflective aerosols can cool the Earth’s surface by reflecting sunlight, while absorbing aerosols, such as black carbon, contribute to warming.

These aerosols impact regional climate patterns, such as monsoon systems, and can exacerbate or mitigate warming depending on their type and concentration.
Aerosols also influence cloud formation and precipitation patterns, which have knock-on effects on the freshwater use boundary by altering rainfall distribution and water availability.

Question 157

Consequences of Land-System Change on Biogeochemical Flows:

Answer 157

The conversion of forests and grasslands to agriculture significantly alters biogeochemical flows. Intensive farming increases the need for nitrogen and phosphorus fertilizers, leading to nutrient runoff into surrounding ecosystems. This runoff contributes to eutrophication, affecting both biosphere integrity and freshwater systems.

Changes in land use reduce the ability of ecosystems, particularly forests, to act as carbon sinks, exacerbating climate change and increasing the reliance on fertilizers, creating a feedback loop between these boundaries.

Question 158

Consequences of Ocean Acidification on Marine Biodiversity:

Answer 158

Ocean acidification, driven by increased CO₂ emissions from climate change, affects marine ecosystems, particularly coral reefs and species that depend on calcium carbonate for their shells and skeletons. This reduction in pH levels causes a loss of genetic and functional diversity in marine ecosystems, threatening the resilience of ocean ecosystems and their ability to provide services such as fisheries and coastal protection.

The loss of coral reefs and marine biodiversity due to ocean acidification also weakens biosphere integrity, as these ecosystems play a critical role in supporting marine life and regulating carbon and nutrient cycles.

Question 159

Ocean acidification

Answer 159

Ocean acidification is a change in the properties of ocean water that can be harmful for plants and animals. Scientists have observed that the ocean is becoming more acidic as its water absorbs carbon dioxide from the atmosphere.

Question 160

Aragonite

Answer 160

Aragonite is a carbonate mineral formed by biological and physical processes. A naturally occurring form of calcium carbonate in the waters, it is used in the formation of shells and skeletons by marine organisms.

Question 161

Consequences of Ocean Acidification on Marine Biodiversity:

Answer 161

Ocean acidification, driven by increased CO₂ emissions from climate change, affects marine ecosystems, particularly coral reefs and species that depend on calcium carbonate for their shells and skeletons. This reduction in pH levels causes a loss of genetic and functional diversity in marine ecosystems, threatening the resilience of ocean ecosystems and their ability to provide services such as fisheries and coastal protection.

The loss of coral reefs and marine biodiversity due to ocean acidification also weakens biosphere integrity, as these ecosystems play a critical role in supporting marine life and regulating carbon and nutrient cycles.

Question 162

Consequences of Ozone Depletion on Biosphere Integrity

Answer 162

Stratospheric ozone depletion allows increased levels of harmful UV radiation to reach Earth’s surface, which has direct effects on biosphere integrity. Increased UV exposure damages plant life, affects genetic diversity, and impairs ecosystems’ ability to function, especially in polar and marine environments.

The ozone layer’s depletion can also impact human health and agriculture, which links to biosphere integrity through its effects on food security and species’ survival.

Question 163

What is climate change mitigation and adaptation?

Answer 163

In essence, adaptation can be understood as the process of adjusting to the current and future effects of climate change. Mitigation means preventing or reducing the emission of greenhouse gases (GHG) into the atmosphere to make the impacts of climate change less severe.

Examples of adaptation measures include large-scale infrastructure changes, such as building defences to protect against sea-level rise.

Mitigation is achieved either by reducing the sources of these gases — e.g. by increasing the share of renewable energies, or establishing a cleaner mobility system.

Question 164

The golden spike (indicator) geologists have settled on for the beginning of the Anthropocene is:

Answer 164

Man-made sediments (sediment of nuclear waste) in lakes.

Question 165

Using gasoline in a car as an example, describe the 1st and 2nd law of thermodynamics.

Answer 165

Gasoline is the source of energy that is converted to turn on the engine of the car.

The used energy is not gone, but converted to movement and also part of it becomes waste/pollution.

In the conversion process, the energy goes from a more useful to less useful form of energy. Meaning that if for e.g. the gasoline initially had 10000 kj of energy, there will only be 8,000 kj of energy converted in the engine. The rest of the energy is scattered and not useful, which we call as entropy.

Question 166

Reinforcing feedback loop using the Albedo effect as an example.

Answer 166

For e.g. with the effect of climate change, the temperature on earth surface has become higher, causing ice to melt in the arctic. With ice melting, less of the sun energy is reflected. Instead, it is absorbed by the ocean making the temperature even warmer.

Question 167

natural greenhouse effect vs enhanced greenhouse effect

Answer 167

The greenhouse effect traps the Sun’s energy at the Earth’s surface. It is essential for life on Earth. The enhanced greenhouse effect is where extra greenhouse gases in our atmosphere trap too much of the Sun’s energy. This causes a warming effect, which some people call global warming.

Question 168

Which characteristics make it likely for an animal to become extinct?

Answer 168

A) Having an extremely small (localized) range
B) Requiring a large territory
D) Living on islands,
E) Having low reporductive success,
F) Needing specialized breeding areas,
G) Having specialized feeding habits.

Question 169

he total matter on our planet is conserved and only moves around between the biotic and abiotic world.

Answer 169

True

Question 170

Melting of polar and glacial ice can lead to greater absorption of
solar heat by the exposed land area, which in turn leads to more
rapid melting. Is this feedback loop balancing or reinforcing?

Answer 170

Reinforcing

Question 171

A natural system consisting of a community of organisms and its
physical environment is known as an ____. In a ____ feedback
system, a change in some condition triggers a response that
counteracts, or reverses, the changed condition. A ____ system is
self-contained; that is, it does not exchange energy with its
surroundings. Such systems are very rare in nature.

Answer 171

ecosystem
negative/balancing
closed

Question 172

What are the characteristics of reinforcing and balancing feedback
loops?

Answer 172

A balancing feedback loop works to maintain (1) system’s dynamic
equilibrium. A reinforcing feedback loop on the other hand, moves
the system further and further away from the target (1) of
equilibrium.

Question 173

Name three characteristics of a system

Answer 173

Are everywhere
Dynamic
Has a purpose

Question 174

What is the natural greenhouse effect? How is it different from the
enhanced greenhouse effect?

Answer 174

The natural greenhouse effect describes the natural process of the
Earth absorbing incoming solar radiation and emitting this as long-
wave infrared radiation (heat) (1) to the lower atmosphere. This
radiation is then absorbed and released by greenhouse gases in
the atmosphere, retaining some of this energy in the atmosphere
instead of travelling back to space. This natural process is essential
to providing a hospitable planet with regular temperatures (1).
However, this natural process can be impacted by the increasing
concentration of greenhouse gases in the atmosphere as a result
of human activity (1). This increases the amount of radiation
‘trapped’ (1) in the atmosphere instead of passing through the
atmosphere and back to space.
Four common greenhouse gases, which are naturally occurring as
well as increasing due to human activities, are water vapor, carbon
dioxide, methane, and nitrous oxide.

Question 175

Name three things/observations that prove that we have entered
the Anthropocene

Answer 175

Chemical compositions of ecosystems and nutrient cycles
Depletion of natural resources
Planetary boundaries are exceeded
Biodiversity loss
Amount of green house gas emissions
Traces in sediments / ”stuff”, plastics

Question 176

In relation to the Planetary Boundaries, what is meant with the
term ‘the great acceleration’?

Answer 176

The Great Acceleration is the dramatic, continous and rougly
simultaneous surge in growth rate across a large range of
measures of human activity, first recorded in mid-20th century
and continuing to this day (1). Within the concept of the proposed
epoch of anthropocene, these measures are those specifically of
humanity’s impact on Earth’s geology and its ecosystems (1)

Question 177

1) What are the main causes of problematic aerosols in the world?

Answer 177

A: The main cause for problematic aerosols are emissions rising from industries and urban areas.

Question 178

In 2023, a team of scientists quantified the boundary for Atmospheric Aerosol Loading for the first
time. Their conclusion was that this boundary has been transgressed and that we are in a so-called
red “danger zone”. Is this true or false?

Answer 178

A: This is false. Despite rising pressure, the boundary has not been transgressed.

Question 179

If we would remove anthropogenic aerosols such as Sulphur from the atmosphere, what would
happen to the average temperature on earth?

Answer 179

A: It is believed that anthropogenic aerosols such as Sulphur have made the planet 0.7°C cooler than it would have been without these particles in the atmosphere. This is because many aerosols have a cooling effect on earth, and they reflect the sun’s energy
back into space. If we remove these aerosols from the atmosphere, this will likely result in warmer temperatures and even faster warming of the planet and more drastic climate change.

Question 180

1) What does “biogeochemical flows” refer to, and why is it identified as a planetary boundary?

Answer 180

“Biogeochemical flows” is one out of nine essential processes for sustaining the stability and resilience of the Earth system. It refers to the flow of important chemical elements like nitrogen (N) and phosphorus (P), but also carbon and Sulphur. This is identified as
a planetary boundary, as these flows are vital for maintaining Earth systems and environmental functions. Human influence on these flows is causing a disruption in the nutrient balance, and can lead to loss of biodiversity and alteration of ecosystem services.

Question 181

Describe one way in which we are disturbing the biogeochemical flows, a consequential problem,
and propose at least one possible solution to the problem.

Answer 181

Model Answer: Using too much synthetic fertilizer to compensate for soil degradation due to intensive agricultural systems à runoff into waters when it rains à nutrients cause algae bloom and
eutrophication in waters, killing marine life.

Possible solutions: regenerative farming to restore soil quality and reduce fertilizer use, poly cropping, planting nitrogen fixating crops and/or cover crops. Planting catchment crops to reduce runoff from
fertilizers.

Question 182

4) What are dead zones, and why do we have them?

Answer 182

Dead zones are areas in oceans or lakes with low oxygen, making them uninhabitable for most marine life. They occur due to nutrient pollution, mainly nitrogen and phosphorus from agricultural runoff, which causes algae blooms. When the algae die, bacteria decompose them, using up oxygen and creating hypoxic conditions.

Question 183

Define the diff justice criterion

Answer 183

Here’s a breakdown of the four justice concepts in relation to the Earth system and sustainability:

A. Interspecies Justice and Earth System Stability
- Interspecies justice refers to the moral obligation to protect not only humans but also other species and ecosystems. This concept rejects the idea of human exceptionalism, recognizing that other species also have a right to exist and thrive.
- In the context of Earth system stability, interspecies justice is about maintaining the integrity and stability of ecosystems, ensuring that human activities do not disproportionately harm other species. Preserving biodiversity and ecosystem services is key to ensuring that the planet remains habitable and resilient for all forms of life, not just humans.

C. Intergenerational Justice
- Intergenerational justice refers to the ethical responsibility to consider the rights and well-being of future generations when making decisions about resource use and environmental impacts. It is about ensuring that today’s actions do not compromise the ability of future generations to meet their own needs.
- This concept is particularly relevant to climate change and other planetary boundaries. Actions taken now, such as reducing greenhouse gas emissions or protecting biodiversity, help prevent irreversible damage to the Earth system that would disproportionately harm future generations.

D. Intragenerational Justice between Countries, Communities, and Individuals
- Intragenerational justice focuses on fairness within the current generation, specifically regarding disparities between different countries, communities, and individuals. This includes addressing inequalities in the distribution of environmental harm and benefits.
- For example, poorer countries and communities often suffer the most from environmental degradation and climate change, despite contributing the least to the problem. Intragenerational justice seeks to ensure that vulnerable populations are protected, and that environmental policies distribute risks and benefits more equitably across society.

These justice principles are crucial for designing sustainability policies that balance the needs of humans and the environment, both now and in the future. They are central to discussions on planetary boundaries and environmental ethics.

Question 184

What would mass biodiversity loss mean for the rest of the planetary boundaries and the Earth System
as a whole?

Answer 184

Mass biodiversity loss would destabilize ecosystems, reducing their ability to sequester carbon, regulate nutrient cycles, and support essential services like water purification and soil fertility. This would exacerbate climate change, disrupt biogeochemical flows,
and increase land degradation. It would also weaken the resilience of ecosystems to recover from shocks, pushing some systems toward tipping points of collapse. The interdependence of biodiversity with other Planetary Boundaries means that its loss would
amplify problems like freshwater scarcity, ocean acidification, and pollution, ultimately threatening Earth’s stability and human well-being.

Question 185

What is the precautionary principle concerning the planetary boundaries? (Discuss proving an
example, choosing one of the planetary boundaries).

Answer 185

The planetary boundary for climate change is primarily defined by the concentration of atmospheric carbon dioxide (CO₂). The boundary is set at 350 parts per million (ppm) of CO₂, a level which corresponds to a global mean surface temperature increase of
around 1°C above pre-industrial levels. This threshold was chosen based on strong evidence that beyond this level, the risk of crossing dangerous tipping points rises significantly. The 350-ppm boundary reflects the precautionary principle, which aims to prevent
irreversible damage to the Earth’s system. For context, the pre-industrial concentration of CO₂ was about 280 ppm, a level that persisted throughout the Holocene. However, since the Industrial Revolution, human activities, particularly the burning of fossil fuels,
have pushed CO₂ levels well beyond this boundary, currently exceeding 415 ppm.

Question 186

Explain the role of forests in the regulation of climate change effects.

Answer 186

Natural ecosystems, particularly forests, play an important role in absorbing atmospheric CO₂. Indeed, forests are essential for both carbon sequestration and local climate regulation. Recent studies suggest that limiting deforestation and increasing reforestation efforts can transform terrestrial ecosystems from carbon sources to carbon sinks, thereby stabilizing the Earth’s carbon cycle and limiting the concentration of CO₂ in the atmosphere.

Question 187

How does the concept of “safe and just” planetary boundaries apply to climate change, and why is it
important to address both environmental and social justice aspects when formulating strategies to
mitigate climate change impacts?

Answer 187

The concept of “safe and just” planetary boundaries applies to climate change by recognizing that the global rise in temperatures must be limited not only to avoid catastrophic environmental tipping points but also to protect vulnerable human populations. A
“safe” boundary for climate change focuses on preventing extreme events such as more intense storms, prolonged droughts, and rising sea levels, which could disrupt ecosystems, agriculture, and water supplies. The “just” aspect, however, stresses that while climate change is a global issue, its impacts are disproportionately felt by those least responsible for causing it. This highlights the importance of balancing efforts to stabilize the Earth’s climate system while also promoting justice for populations who are most
vulnerable to adverse effects.

Question 188

How do polar stratospheric clouds impact the ozone layer?

Answer 188

Polar stratospheric clouds accelerate the impact of chlorine, such as human-made CFCs, by providing chlorine surface in the form of ice crystals and preventing chlorine deactivation.

Question 189

2) What is the difference between stratospheric and tropospheric ozone?

Answer 189

Stratospheric ozone helps to shield dangerous UV rays from earth, while tropospheric ozone is a human-made pollutant.

Question 190

3) Why is the Montreal Protocol considered successful?

Answer 190

The Montreal Protocol is successful due to the fact that it is universally ratified, it was put into action rapidly after the problem of ozone depletion was discovered and it has changed the trajectory of the ozone hole.

Question 191

1) Name 3 boundaries that are affected by Land-System Change and explain why?

Answer 191

. Biodiversity Loss (Biosphere Integrity):
Land-system changes, such as deforestation, urbanization, and agricultural expansion, drastically reduce natural habitats. This destruction leads to the loss of species and ecosystems. Deforestation, for example, fragments habitats and forces species into smaller areas, making them more vulnerable to extinction. The degradation of ecosystems disrupts the balance of biodiversity, affecting ecosystem services like pollination and soil fertility, which are vital for human and ecological well-being.

2. Biogeochemical Flows (Nitrogen and Phosphorus Cycles):
   Conversion of natural landscapes into agricultural land intensifies the use of fertilizers, which alters the nitrogen and phosphorus cycles. Excessive use of these nutrients can lead to eutrophication of freshwater and marine ecosystems, causing harmful algal blooms, oxygen depletion, and loss of aquatic biodiversity. Land-system changes increase the pressure on these cycles by disrupting the natural flow of these elements in ecosystems.
3. Climate Change:
   Land-system changes, such as deforestation and land degradation, release stored carbon into the atmosphere, contributing to climate change. Forests and natural landscapes act as carbon sinks, absorbing CO2 from the atmosphere. When these areas are converted into agricultural or urban land, not only is this carbon storage capacity lost, but the carbon stored in vegetation and soil is released, exacerbating global warming.

Question 192

Name two potential solutions to the problem of novel entities and explain how they could help?

Answer 192

Multiple answers possible. Circular economy, screening, green chemistry etc. Explanations for why the solution helps should either be related to how it helps define and screen the boundary, or how it is a precautionary measure that helps release less chemicals all together.

Question 193

Name one other planetary boundary that shows a strong synergy with Novel Entities, both in its
hazards as well as its potential solutions.

Answer 193

e.g., Stratospheric ozone depletion, Atmospheric aerosol loading

Question 194

1) What is the main cause of ocean acidification?

Answer 194

In short: emissions of carbon dioxide, mostly from human activities, that are absorbed in seawater is the main cause of ocean acidification.

Question 195

In what way is plankton affected by ocean acidification and what could a consequence of a disruption
to plankton populations be?

Answer 195

Plankton need carbonate ions to build their shells and without sufficient access to it plankton populations are at risk of decline. Since they are the basis of the marine food chain, a disruption of the plankton population could be devastating to all marine ecosystems.

Question 196

3) What are some of the disadvantages of alkalinization applied to the ocean?

Answer 196

Ecosystem disruption, marine life impact, quick lime necessarily has large energy and fossil fuel CO₂ footprints, cost of the materials and infrastructure, large scale application is difficult and implementing it locally can create imbalance in the ecosystem.

Question 197

Human induced change via nutrient cycles

Answer 197

Carbon cycle;
Shifting of carbon from underground deposits through combustion of fossil fuels and deforestation.
Implications? Increased CO2 in the atmosphere (from preindustrial 0,029% to 0,04%); Climate change.

Nitrogen cycle;
Increased amount of fixed nitrogen through fertilisers. Combustion of fossil fuels, releasing NOx.
Implications?—-
Decreased biodiversity in enriched land;
Contamination of groundwater;
Runoff-> eutrophication;
Acid deposition;
Poor air quality.

Phosphorus cycle;
Use of phosphorus in fertilisers and detergents.
Implications? Depletion of resource; Limiting nutrient; Eutrophication.
Sulphur cycle;
Combustion of coal and oil. Extraction of (some) metals through smelting.
Implications? Creation of SO2-> acid deposition-> Damage to ecosystems.

Hydrologic cycle;
Release of aerosols through combustion. Release of GHG. Land use (for e.g. dams, irrigation).
Implications?–
Formation of aerosols-> alters cloud formation/precipitation patterns;
Climate change-> ice-cap melting etc.; (Locally) altered patterns for water infiltration/retention/evapotranspiration

Question 198

Renewable / Non-Renewable Resources

Explain the impact of population and affluence on consumption.

Answer 198

a
Renewable resources are those that nature replenishes/replaces fairly rapidly and can be used forever as long as they are not overexploited in the short term.

Non-renewable resources are present in limited supply and are diminished by use.

Question 199

Explain the impact of population and affluence on consumption.

Answer 199

a
As population increases, people can exceed the capacity of a region to support basic needs. When consumption by individuals substantially exceeds these basic needs, the resources in a region will be exceeded even more quickly.

Question 200

What is an individual’s ecological footprint?

Answer 200

n individual’s ecological footprint is the amount of productive land, fresh water, and ocean required on a continuous basis to supply that person with food, energy, water, housing, material goods, transportation, and waste disposa