Science of Sustainability Final Review

Deductive Inference

Apply general rules to infer something about a specific case.

Inductive Inference

Observe specific cases to infer a general rule.

Deductive or Inductive Inference? All men are mortal. Socrates is a man. So Socrates must be mortal.

Deductive

Deductive or Inductive Inference? I’ve bitten several people. No one liked it. So people don’t like to be bit.

Inductive

Absolute Inference

Absolute relationship between variables/parts of a system.

Statistical Inference

Probabilistic relationship between variables/parts of a system.

Absolute or Statistical Inference? Smoking causes lung cancer. Bill smokes. So Bill will get lung cancer.

Absolute Inference

Absolute or Statistical Inference? Smoking increases the likelihood of getting lung cancer. Bill smokes. So, Bill is more likely to get lung cancer than if he didn’t smoke.

Statistical Inference

Weathers et al. definition of an ecosystem?

An interacting system made up of all the living and nonliving objects in a specified volume of space.

Advantages of Weathers et al. definition of an ecosystem: Mass Balance

Makes it possible to use mass balance to track the movement of materials that come into the ecosystem.

Advantages of Weathers et al. definition of an ecosystem: Black Box Approach

Makes it possible to measure the total activity of an ecosystem without having to measure all the parts and exchanges within the ecosystem.

Advantages of Weathers et al. definition of an ecosystem: Importance of ALL Components

Recognizes the importance of both living and nonliving components of the system.

Advantages of Weathers et al. definition of an ecosystem: Boundaries

Gives the investigator the power to select the spatial and temporal boundaries of the system being studied.

How do ecologists regard people?

Ecologists regard people as part of an ecosystem and include people in their studies.

1st Law of Thermodynamics

Energy can change forms, but cannot be created nor destroyed.

2nd Law of Thermodynamics

• Entropy of a closed system always increases

• Irreversibilities during processes do not allow you to recover the original quality of energy you put in a system.

Ecosystems create order and decrease entropy. Does this make ecosystems an exception from the 2nd Law of Thermodynamics?

No, Earth and ecosystems are open systems.

Which Law of Thermodynamics is concerned with energy quantity?

1st Law of Thermodynamics

Which Law of Thermodynamics is concerned with energy quality?

2nd Law of Thermodynamics

Structure of an Ecosystem

What ecosystems look like.

What is included in the Structure of an Ecosystem?

• Components: what is in the ecosystem.

• Organization: how the ecosystem is organized.

Examples of Ecosystem Components (part of ecosystem structure):

• Bacteria, plants, animals

• Air, water, nutrients

Examples of Ecosystem Organization (part of ecosystem structure):

1. Pathways of matter and energy

2. Distribution (e.i. patchiness)

3. Size location

Function of an Ecosystem

How an ecosystem works

Examples of Ecosystem Function:

• Consuming energy and transforming materials.

• More useful energy:

  1. Solar radiation

  2. Chemical potential energy

• Less useful energy:

  1. Heat

• Open vs. closed systems

• Material function (source or sink).

Ecosystem Dynamics

Ecosystem change over time

Dynamics: External Forces

Forces that act outside a system.

• Nutrients inputs, increase in temperature.

Dynamics: Internal Dynamics

Forces that act in a system.

• Age of tree strand, succession.

Photosynthesis Equation:

CO₂ + H₂O + light → (CH₂O) + O₂

Oxic Respiration Equation:

CH₂O + O₂ → CO₂ + H₂O + energy

Example of Anaerobic Respiration:

CH₃COOH → CH₄ + H₂O

Photosynthesis is an ___ of carbon.

Reduction (4+ to 0)

Oxic Respiration is an ___ of carbon.

Oxidation (0 to 4+)

Anaerobic Respiration does not include ____ in it processes.

Oxygen

Oxidation is the…

loss of electrons

Reduction is the…

gain of electrons

Oxidation number of carbon in CO₂:

4+ (O is 2-)

Oxidation number of carbon in CH₄:

4- (Hydrogen is +1)

What is Gross Primary Productivity (GPP)?

All carbon dioxide fixed into organic matter irrespective of any respiratory losses.

What is Net Primary Productivity (NPP)?

The rate at which organic matter is available for other uses beyond simply supporting energy costs (i.e., respiration) of the primary producers (Ra).

What is Net Ecosystem Productivity (NEP)?

The portion of gross primary production that is not respired by autotrophs or heterotrophs.

What is Ra?

Autotrophic Respiration

What is Rh?

Heterotrophic Respiration

What is Re?

Ecosystem Respiration; Sum of Ra and Rh

Autotrophs

Organisms that produce their own food/energy.

Heterotrophs

Organisms that consume other organisms for food/energy.

GPP =

NPP + Ra

NEP + Re

NPP =

GPP - Ra

NEP =

GPP - Re

What are the terms: dCorg = NEP + I + CM - Ex - Oxnb 

dCorg = organic carbon accumulation

NEP = net ecosystem productivity

I = imported carbon that hasn’t been respired

CM = net consumer movement

Ex = exported organic carbon

Oxnb = non-biological oxidation of carbon (i.e. fire)

Climate Change Detection

Demonstrating that climate has changed in a defined statistical sense.

Climate Change Attribution

Identifying the most likely causes of observed change with some level of confidence.

What is the greenhouse effect?

When greenhouse gases absorb the sun's heat that radiates from the Earth's surface, trap it in the atmosphere and prevent it from escaping into space.

How has the greenhouse effect changed?

The greenhouse effect has intensified due to a significant increase in atmospheric greenhouse gas concentrations starting around 1900 (industrial revolution).

What are 5 pieces of evidence that show the Earth is warming?

• Sea level rise

• Increased surface temps

• Increased ocean temps

• Loss of ice sheets

• Retreating glaciers

What role do ice cores play in our understanding of climate change?

• Water traps air as it freezes. By sampling air bubbles trapped deep in the arctic ice, scientists are able to see the composition of the atmosphere many years (or millennia) ago. 

• Helped make the correlation between greenhouse gas concentrations and climate change.

Key Drivers of Climate Change: Milankovitch Cycles

Changes in the shape of the Earth’s orbit, level of axis tilt, and how cleanly the Earth rotates (wobble/precession).

• Natural Driver

Key Drivers of Climate Change: Sunspots

Increases and decreases in the sun’s intensity.

• Natural Driver

Key Drivers of Climate Change: Albedo

Energy that enters the system but is reflected out immediately.

• Natural, but impacted by anthropogenic factors

Key Drivers of Climate Change: Greenhouse Effect

Effect that doesn’t allow heat to escape Earth’s atmosphere.

• Billions of years old

• Natural, but impacted by anthropogenic factors

What were the key drivers of previous shifts from glacial to interglacial periods?

Milankovitch Cycles

What is the primary driver of contemporary climate change?

Greenhouse Effect; the increase in greenhouse gas concentrations is the primary contemporary driver of climate change.

What is the difference between the rate of climate change today versus previous shifts?

The rate of climate change today is many times faster than previous shifts.

• Previous Warming: 4 to 7 C in 5000 years

• Past Century: 0.7 C [10x faster]

• Projected  Next 100 Years: 2 to 6 C [20x faster]

What role does the ozone hole play in climate change?

The ozone hole does not play a role in climate change, but can cause other environmental and social issues.

The 3 Main Greenhouse Gases

1. Carbon Dioxide (CO₂)

2. Methane (CH₄)

3. Nitrous Oxide (N₂O)

Major Carbon Stocks

1. Land/Earth

2. The Ocean

Land as a Carbon Stock

• Driven by photosynthesis

• Net ecosystem production is substantial and results in the bulk of the stored carbon.

The Ocean as a Carbon Stock

• Driven by diffusion (chemical/physical reactions).

• Nearly all of gross primary production is respired.

Natural Flows: Rock Weathering

• Carbon Inflow

• Relatively Small (0.1 to 0.3)

Natural Flows: Volcanism

• Carbon Outflow

• Relatively Small (0.1)

Natural Flows: Gross Photosynthesis

• Carbon Inflow

• Relatively very large (123 = 108.9 + 14.1)

Natural Flows: Total Respiration and Fire

• Carbon Outflow

• Relatively very large (118.7 = 107.2 + 11.6)

• Less than Photosynthesis (inflow)

Natural Flows: Freshwater Outgassing

• Carbon Outflow

• Relatively small (1.0)

Natural Flows: Ocean - Atmosphere Exchange

• Both a Carbon Outflow and Inflow

• Relatively Large

• Inflow is greater that Outflow

  • Inflow: 80 = 60 + 20

  • Outflow: 78.4 = 60.7 + 17.7

Anthropogenic Flows: Fossil Fuels and Cement Production

• Carbon Outflow

• Very Large (7.8 ± 0.6)

Anthropogenic Flows: Net Land Use Change

• Carbon Outflow

• Relatively Large (1.1 ± 0.8)

• Less than fossil fuels/cement

Historic Role of the Ocean

Carbon Source

Modern Role of the Ocean

Carbon Sink

Higher temperatures ___ the concentration of CO₂ in water.

Reduces; hotter water decreases the solubility of CO2, causing the ocean to release CO2 into the atmosphere.

Lower temperatures ___ the concentration of CO₂ in water.

Increases; colder water can absorb more CO2.

At a constant temp, a(n) ___ in partial pressure increases the concentration of CO2 in water.

Increase

At a constant temp, a(n) ___ in partial pressure decreases the concentration of CO2 in water.

Decrease

A low concentration of CO₂ in the atmosphere results in a ___ partial pressure. This partial pressure leads to a ___ CO₂ concentration in water.

Low; low

A high concentration of CO₂ in the atmosphere results in a ___ partial pressure. This partial pressure leads to a ___ CO₂ concentration in water.

High; high

Ocean Acidification

• The gradual pH decrease (more acidic) of the ocean.

  • The ocean’s pH is directly proportional to CO2 concentration.

  • Increased diffusion of CO2 into the ocean is directly responsible for ocean acidification.

Climate Mitigation

Measures taken to reduce greenhouse gases, thereby decreasing the pace and magnitude of climate impacts.

Climate Adaptation

Measures taken to handle the climate impacts as they come.

Economic Impacts of Mitigation (According to Martinich & Crimmins, 2019)

Climate mitigation would reduce economic damages across all 22 sectors (except 1, urban drainage).

• Lessens damages associated with extreme weather decreases

• Millions to tens of billions of US dollars in annual benefits are saved by the end of the century.

“S” in a Feedback Loop Means…

Same

“O” in a Feedback Loop Means…

Opposite

Reinforcing Feedback Loop

A process or behavior amplifies the initial action, leading to further growth or intensification of that behavior.

Balancing Feedback Loop

A process of behavior that stabilizes a system by counteracting changes.

Which numbers would have S arrows?

1, 4, 5, 6, 7, 8, 9, 10, 12, 14

Identify the Reinforcing Feedback Loops.

• Loop 8-5-1

• Loop 2-3-4

• Loop 5-6-10

• Loop 5-14-13-11-9

Command and Control

When the government sets specific conditions, such as required equipment or maximum allowable flow rate out of a smokestack.

Market-Based Energy Polices

Use economic incentives to encourage and discourage behaviors.

What are the 3 Market-Based Energy Policies?

1. Clean Energy Standards

2. Carbon Tax

3. Cap and Trade

Market-Based Energy Policies: Clean Energy Standards

The government requires a specific proportion of energy production in a state or country to come from low- or zero-carbon sources.

• Doesn’t set specific emission levels or prices.

Market-Based Energy Policies: Carbon Tax

When the government adds an additional fee based on the amount of carbon emissions produced, which raises the price of carbon intensive activities.

• Sets price but not emission levels.

Market-Based Energy Policies: Cap and Trade

When the government sets a total allowable level of pollutant for an industry and allows individual actors to buy and sell their individual allowances within that limit.

• Sets emission levels but not price.