Chapter 1: Foundations of climate change

Question 1

Define climate change

Answer 1

Climate change describes the long-term differences in the statistics of weather measured over multi-decadal periods.
(Ch 1.0)

Question 2

Using the dice analogy, explain climate change

Answer 2

Climate change means that the die are changing. As the climate warms, we would find that hot temperature appears on 6 out of the 6 sides of the temperature die.
(Ch 1.0)

Question 3

Define Weather

Answer 3

Weather refers to the exact state of the atmosphere at a particular location and time. (Ch 1.0)

Question 4

Define Climate

Answer 4

Climate refers to the long-term patterns or statistics of the weather, typically estimated from weather statistics over several decades, typically 30 years or more.
eg. average daily high (statistics) temperature for Vancouver in August is 84°F/29°C. (Ch 1.0)

Question 5

What are the difference qualities of climate (besides temperature)?

Answer 5

1. Temperature
2. Precipitation
3. Humidity
4. Cloudiness
5. Visibility
6. Wind
   (Ch 1.0)

Question 6

Using the dice analogy, explain the difference between weather and climate

Answer 6

The day’s weather is the result of a single roll of the weather die.
Climate is the statistics from many rolls of the die.
Climate can be determined by looking at the die (eg. if 3 sides hot, 3 sides cold, can infer that hot and cold temperatures are equally likely).
(Ch 1.0)

Question 7

What is the difference between climate change and global warming?

Answer 7

Global warming refers to increases in temperature, whereas climate change includes changes in other aspects of the climate (eg. precipitation, sea level). (Ch 1.0)

Question 8

What are the general trends of modern climate change (last 150 years)?

Answer 8

1. Global Annual Average Temperature increase by 1.2 °C (1850-1900 v 2013-2022)
2. Supported by satellite measurement of global monthly average temperature

Indirect evidence includes:
3. Arctic sea extent (in millions of square km) reducing
4. Glacier Ice reducing (tonnes/m2)
5. Ocean heat content (Joules) top 2km / 1.25 miles of ocean gaining energy
6. Sea level rising
(Ch 1.1)

Question 9

Describe how global warming is distributed.

Answer 9

1. Warming is no uniform.
2. Land warmed more than ocean.
3. Northern hemisphere warmed more than Southern hemisphere.
4. 85% of world population live in northern hemisphere, meaning they experience more warming.
   (Ch 1.1)

Question 10

What are the 2 key reasons for rising sea levels?

Answer 10

There are 2 key contributing factors.
1. Melting of grounded ice runs into the ocean. Total amount of water in ocean increases resulting in sea level rises.
2. Thermal expansion - Water expands when it warms. (Ch1.1)

Question 11

Melting of _____ ice does not raise sea levels.

Answer 11

Melting of sea ice does not raise sea levels. (Ch 1.1)

Question 12

What conclusion the IPCC recently made about the confidence in the warming of the climate system?

What is the likely range/ estimate of human impact? °C

Answer 12

The IPCC has described the confidence in the warming of the climate system since the early twentieth century as unequivocal, beyond doubt. (Ch 1.1)

AR(6) conclusion: It is unequivocal that human influence has warmed the atmosphere, ocean, and land. Widespread and rapid changes in the atmosphere, ocean, cryosphere, and biosphere have occurred.

The likely range of total human-caused global surface temperature increase from 1850–1900 to 2010–2019 is 0.8°C to 1.3°C, with a best estimate of 1.07°C.

i.e responsible for 100% (1.07/ 1.10) of observed warming since warming over this period is 1.1°C.

likely being confidence of 66%.

Question 13

Based on the available evidence, what is the likelihood that the conclusion is currently warming is wrong?

Answer 13

Virtually no chance that the conclusion is wrong.

i.e Virtually no chance that enough data sets could be wrong,
by far enough, and
in same direction.
(Ch 1.1)

Question 14

How can we extract climate information from tree rings?

Answer 14

Tree growth follows annual cycle, imprinted in rings in trunk.

In spring, grow rapidly and produce light coloured wood.
In autumn, growth slows and produce dark coloured wood.

Warm and wet years - trees grow more and produce wider rings. (i.e tells us about temperature and precipitation) - by measuring size of rings, can estimate the local climate for each year. (Ch. 1.2)

Question 15

What are different proxies we can use to measure the climate in the past? (summary)

Answer 15

1. Tree rings
2. Corals
3. Speleothems (e.g., stalactites and stalagmites)
4. Ice cores (chemical composition of ice)
5. Ocean sediment cores (composition of mud at bottom of the ocean)

Question 16

What are the different methods for measuring non-anthropogenic climate change?

Answer 16

Tree rings - millennium (1000 years)
Speleothems - few 100 thousand years
Ice Cores - past million
Corals - millions of years
Ocean sediment cores - tens of millions of years.

1. Tree rings: These measurements can reveal climate variations in regions where trees grow and experience seasons for the last millennium.
2. Speleothems (e.g., stalactites and stalagmites): These cave structures can yield estimates of the climate in the region around the cave over the past few hundred thousand years.
3. Ice cores: Measuring the chemical composition of ice (mainly in Greenland and Antarctica) yields estimates of the climate over the past million years or so.
4. Corals: Analysis of the skeletons of these sea creatures can yield climate conditions in the ocean over millions of years.
5. Ocean sediment cores: Analyzing the composition of the mud at the bottom of the ocean provides information about the climate covering the past tens of millions of years.
   (Ch. 1.2)

Question 17

Describe the climate fluctuations over Earth’s history?

Answer 17

1. 50 million years ago, Earth was much warmer. No permanent ice on planet. Climate has generally been cooling.
2. Over last 410,00 years, cycling between ice ages and interglacials (warmer periods). Each cycle about 100,000 years.
3. Last ice age ended 10,000 years ago, reaching its coldest point 20,000 years ago.
4. In the last 11,000 years (holocene), temperature peaked 7000 year ago and bottomed out 200 to 300 years ago (little ice age). Then earth began warming. By late 2010s was1°C warmer than the Little Ice Age.
   (Ch. 1.2)

Question 18

What was the Earth’s climate like, 50 million year ago?

Answer 18

50 million years ago, Earth was much warmer. No permanent ice on planet. Climate has generally been cooling. (Ch 1.2)

Question 19

What was the Earth’s climate like, over the last 410,000 years?

Answer 19

Over last 410,00 years, cycling between ice ages and interglacials (warmer periods). Each cycle about 100,000 years. (Ch. 1.2)

Question 20

Describe the last ice age

Answer 20

Last ice age ended 10,000 years ago, reaching its coldest point 20,000 years ago. (Ch. 1.2)

The carbon dioxide in the atmosphere was 280 ppm. Today is it 417 ppm.

(Ch 1.9)
Global annual average temperature was about 6°C colder than that of our present climate.

Glaciers covered much of N.America and Europe, sea level approx 100m (330 ft) lower than today.

Question 21

Describe the Holocene

Answer 21

Refers to the last 11,000 years (holocene).

Temperature peaked 7000 year ago and bottomed out 200 to 300 years ago (little ice age).

Then earth began warming. By late 2010s was 1°C warmer than the Little Ice Age.
(Ch. 1.2)

Question 22

What conclusions can we make about modern warming based on Earth’s past climate?

Answer 22

Global average temperature difference between an ice age and interglacial is about 6°C.

1°C warming since the 19th century is not an insignificant amount.

Warming is 16 times faster than the average rate of warming coming out of the last ice age (6°C in 10k years is roughly 0.06°C per century) 16 x 0.06 = 0.96

(Ch. 1.2)

Question 23

What is the Earth’s energy balance?

Answer 23

The temperature of the climate system is determined by the energy balance.

When the energy budget balances, the temperature on earth stays relatively constant.

Energy from sun reaching the earth must equal the energy the earth radiates back to space. (Ch 1.3)

Question 24

Describe the source of energy for Earth’s climate

Answer 24

The source of energy is sunlight. Mainly visible radiation. Provides 340 W/m2 of energy to the Earth (global and annual average).
(Ch 1.3)

Question 25

What percentage of sunlight is reflected back to space? What is the net solar energy absorbed by the Earth?

Answer 25

30% of incoming sunlight is reflected back. Net solar energy absorbed by Earth is 238 W/m2.

238/ 340 = 70% (Ch. 1.3)

Question 26

What determines the amount of energy the earth radiates to space?

Answer 26

Temperature of the planet and composition of the atmosphere (esp. amount of greenhouse cases).

Question 27

Describe the greenhouse effect

Answer 27

1. Greenhouse gases in atmosphere absorb infrared radiation (radiant heat).
2. They reduce the amount of energy Earth radiates to space.
3. A planet with more greenhouse cases in atmosphere must be warmer than one without - discovered by Joseph Fourier in 1820s
   (Ch. 1.4)

Question 28

What happens when greenhouse gases in the atmosphere increase?

Answer 28

The atmosphere will trap more heat, leading to higher temperature. (Svante Arrhenius 1896, Guy Calendar 1938)

Question 29

What are the components of the atmosphere?

Answer 29

1. molecular nitrogen (N2)
2. oxygen (O2),
3. inert gas argon (Ar).

Question 30

What are the constituents in atmosphere that generate greenhouse effect?

Answer 30

Greenhouse effect is caused by MINOR constituents in the atmosphere.

1. Water Vapor (H2O) - traps most heat!
2. Carbon Dioxide (CO2) - 2nd largest contributor despite small concentration. strong 0.0417% or 417 parts per million (PPM)
3. Methane.

Question 31

How much carbon dioxide is there in the atmosphere? (in 2022)

Answer 31

417 parts per million. i.e 417 CO2 molecules per million molecules of air.
(Ch 1.4)

Question 32

How has carbon dioxide in the atmosphere changed since the middle of the 20th century?

Answer 32

The Keeling Curve shows a long-term upward trend.

In late 1700s - 280 ppm
by early 2020s - 417 ppm (increased by 50%)

Question 33

How has human activity contributed t the increase in carbon dioxide in the atmosphere?

Answer 33

Increase is carbon dioxide is primarily due to combustion of fossil fuels.

Question 34

How do we know that human activity is responsible for the increase in carbon dioxide in the atmosphere?

Answer 34

1. Carbon dioxide began increasing at beginning of 19th century, as world began generating energy from fossil fuel combustion.
2. Past 50 years, increase in carbon dioxide averages 44% of what human release into the atmosphere in that year. (i.e tracks human emissions very closely).
3. Chemical composition of atmospheric carbon dioxide shows the isotopic composition that is consistent with carbon dioxide from fossil fuels. (compared to isotopic fingerprint of air bubbles trapped in glacial ice)

(Ch. 1.5.1)

Question 35

What are the different carbon isotopes?

Answer 35

Carbon has 6 protons, and varying number of neutrons.

Carbon - 12 (light) is most abundant. Plant materials enriched in carbon-12.
Carbon 13 (heavy - volcanic emissions enriched in carbon-13.

Carbon - 14 (radioactive)

(Ch. 1.5.1)

Question 36

Describe how the changing isotopic composition of carbon dioxide in the atmosphere points to fossil fuels ?

Answer 36

The ratio of Carbon 13 to Carbon 12 has declined in last 4 decades. Relative amount of carbon 14 has also declined.

The source of carbon dioxide must come from plants (depleted in carbon 13 and carbon 14 has decayed to non-detectable levels)

And given size and speed of increase, points to fossil fuels (which are the remains of millions of years of carbon uptake by plants).

https://www.climate.gov/news-features/climate-qa/how-do-we-know-build-carbon-dioxide-atmosphere-caused-humans

(Ch 1.5.1)

Question 37

What proportion of carbon dioxide released by humans, is removed? And how?

Answer 37

Increase in carbon dioxide in atmosphere averaged 44% of CO2 released by humans.

56% of CO2 release by humans is not released into atmosphere. (i.e removed). About half is absorbed by ocean leading to ocean acidification.

Question 38

Describe methane and its impact on the climate

Answer 38

Methane CH4 is a powerful greenhouse gas.

Each kg of methane traps as much heat as 28kg of CO2.

It has a Global Warming Potential (GWP) of 28

Increase from 0.8 ppm to 1.9 ppm since pre-industrial.

Question 39

What is Global Warming Potential? What are the implications of a higher GWP?

Answer 39

Global Warming Potential is the heat-trapping power relative to CO2.
For example, methane has a GWP of 28.
It means it is 28x better for the climate to reduce emissions of 1 tonne of methane than it is to reduce same volume of CO2.

Question 40

Describe Ozone and its impact on the climate

Answer 40

Ozone (O3), a molecule has multiple effects on the atmosphere.
1. absorbs ultraviolet radiation which is harmful to humans and natural ecosystem.
2. powerful greenhouse gas that traps heat.

Human activity contributed to the increase in precursors of ozone (emission of hydrocarbons and nitrogen oxide).

We are referring to the ozone in the lower atmosphere, not the ozone in the stratosphere (discovered to be facing destruction by humans in 70s/ 80s).
(Ch 1.5.2)

Question 41

What are the contributions of greenhouse gases and aerosols to climate change?

Answer 41

Ch 1.5.2 Table 1.1 -Global warming potential, atmospheric lifetime, increase in abundance and fraction of total greenhouse radiative forcing.
(Ch 1.5.2)

Question 42

Describe aerosols and its impact on climate change, including human contribution to aerosols.

Answer 42

Aerosols are tiny particles that remain suspended in the atmosphere for days or weeks, because the buoyant forces are similar to force of gravity.

Aerosols reflect incoming solar radiation bace to space - net effect is to cool the climate.
They affect cloud formation, making clouds more reflective which is an additional cooling mechanism.

This cooling effect has partially offset the warming effect in greenhouse cases.

Human contribution to aerosols:
1. burning of fossil fuels that contain sulphur impurities - sulphur gases react with other constituents to form sulphate aerosols.
2. Incomplete combustion produces soot - i.e black carbon aerosols (soot)
3. Mineral dust from agricultural activities (harvesting, plowing), changing surface water features (drying out of lakes) and industrial practices (eg. cement production).

(Ch 1.5.2)

Question 43

Explain the non-human mechanisms that contribute to climate change

Answer 43

1. Tectonic processes (affects climate over millions of years, too slow to be responsible for modern warming)
2. Output of the sun - no evidence of change.
3. Orbital variations - responsible for ice ages, but not for modern warming.
4. Unforced variability - minor role at most.
5. Greenhouse gases - evidence supporting greenhouse gases as the cause of warming is immense.

Question 44

How does tectonic processes affect the climate?

Answer 44

The Earth’s continents are moving and, over tens of millions of years, this continental drift can substantially alter the arrangement of the continents across the Earth’s surface.

Such changes can lead to changes in the climate through several mechanisms.

For example, the movement of a continent toward the poles can lead to the growth of an ice sheet on the continent. Growth of a continental ice sheet will lead to more incoming sunlight being reflected back to space, which will tend to cool the climate.

However, this process is exceedingly slow—the movement of the continents occurs over geologic time scales, e.g. millions of years.

Thus, this cannot be responsible for modern warming because it is simply too slow.

Question 45

How does out of the sun affect the climate?

Answer 45

The ultimate energy source for the climate system is the Sun.

But scientists have been measuring the output of the Sun since late 1970s, and there is no long-term trend that could explain the very rapid warming over that period.

Prior to that, the Sun’s output must be inferred indirectly from other measurements eg, number of sunspots, which people have counted for many hundreds of years, or from chemical proxies such as the carbon-14 content of plant material.

Estimates suggest that the Sun has changed little over the past few hundred years. Thus, we can eliminate this as a cause of modern global warming.

Question 46

How does orbital variations affect the climate?

Answer 46

Earth’s orbit changes in 3 ways.

1. Shape of orbit - more/ less elliiptical over 100,000 years.
2. tilt of earth - 23.5°, cycles (22.3° to 24.5°) over a period of about 41,000 years
3. day of closest approach of earth to sun. presently in January, cycles through the calendar over a period of about 23,000 years.

Not cause of modern warming - orbit does not change much over a century. But variations responsible for ice ages.

Question 47

How does unforced variability affect the climate?

Answer 47

Unforced variability refers to variation in earth’s climate system without an imposed energy imbalance.

eg. El Niño/ Southern Oscillation (ENSO)

only a minor role in modern warming.

Question 48

How does greenhouse gas affect the climate?

Answer 48

The evidence supporting the cause of the warming being the increase in greenhouse gases over the last two centuries is immense.

First, the laws of physics tell us that adding carbon dioxide, or any other gas that absorbs infrared radiation, to the atmosphere should warm the planet by affecting the planet’s energy balance.

Second, it is a fact that humans are adding carbon dioxide to the atmosphere. The timing of warming, beginning in the nineteenth century, after the industrial revolution, and the magnitude of the warming, also match scientific theory.

3. Finally, the geologic record shows that changes in climate are frequently associated with changes in greenhouse gases.

For example, carbon dioxide changes during ice-age cycles (Figure 1.3b) are thought to play a key role in amplifying the size of the climate variations, although the exact mechanism that alter the concentration of atmospheric carbon dioxide during ice-age cycles is an active area of research.

Question 49

Explain the human mechanisms that contribute to climate change

Answer 49

CO2 and other greenhouse cases have caused a combined positive heating change to radiative forcing. Aerosols have caused a negative (cooling) change. Net human contribution is positive.

Note - water vapour’s main role in climate change is to amplify changes caused by other things.

Question 50

Describe the role of water vapour in climate change.

Answer 50

Water vapour is most important greenhouse case.

Amount of water vapour is atmosphere driven by earth’s temperature.

Earth cools, less water vapour.
Earth warms, more water vapour.

Water Vapour Feedback - It amplifies effect from other things. potential to double/ triple amount of warming from CO2 alone.

initial warming leads to more atmospheric humidity. This leads to additional warming, which then feeds back to increase humidity.

Question 51

Describe the Shared Socioeconomic Pathways

Answer 51

The Integrated Assessment Modelling Consortium developed alternative pathways:

1. differing in the amount of economic growth and amount of climate-safe energy that is deployed, and
2. leads to different amounts of CO2 emitted into the atmosphere.
3. Amount of climate change estimated by Global Climate Model (GCM).

SSP1 - 2°C/3.6°F
SSP2 - 3°C/5.4°F
SSP3 - 4.5°C/8°F
SSP5 -5.5°C/10°F

Earlier set of scenarios were Representative Concentration Pathways (RCPs) - they are concentration pathways without any corresponding economic drivers. Each RCP has roughly similar SSP scenario.

Question 52

Describe SSP1

Answer 52

Taking the Green Road

SSP1 is a sustainable world where the world’s economies gradually shift towards a more environmentally friendly path.

Because of strenuous efforts to adopt renewable energy, emissions are currently peaking and expected to decline throughout the rest of the century.

In fact, SSP1’s emissions go negative around 2075, meaning that humans are pulling more carbon out of the atmosphere than they are releasing.

The low emissions associated with this scenario lead to temperature increases of 2°C/3.6°F above the preindustrial climate.

Question 53

Describe SSP2

Answer 53

Middle of the road.

SSP2 is a world that follows the trends of our world today, leading to generally declining emissions over the twenty-first century due to widespread adoption of renewable energy (although slower than in SSP1).

Economic growth is similar to SSP1. The carbon dioxide emissions associated with this scenario lead to temperature increases of 3°C/5.4°F above the pre- industrial climate.

Question 54

Describe SSP3

Answer 54

Regional Rivalry (Rocky Road)

SSP3 is a world where economic inequality gets worse, leading to increasing conflict between regions.

Because of this, economic growth is slow and adoption of new energy technology is also slow, leaving the world almost entirely dependent on fossil fuels.

The combination of these leads to carbon dioxide emissions increasing throughout the century, reaching around double today’s values in 2100.

Temperature increases in this world are 4.5°C/8°F above the preindustrial climate.

Question 55

Describe SSP5

Answer 55

Fossil Fueled Development (Taking the highway)

SSP5 is similar to SSP1, but emphasizes economic growth rather than sustainability.

Economic growth is very high and fossil fuels power a significant fraction of this growth.

This leads to carbon dioxide emissions increasing throughout the century, reaching more than triple today’s values in the late-twenty-first century.

Temperature increases in this world are 5.5°C/10°F above the preindustrial climate.

Question 56

Describe the distribution, frequency and intensity of climate driven environmental impacts across geography and time

Answer 56

1. Warmer temperature.
2. Precipitation
3. Sea level/ Ocean acidification
4. Albedo Effect, Polar Amplification and Positive Feedback.
5. Extreme Weather Events.

Question 57

Describe the impact of modern climate change - temperature.

Answer 57

Continents warm more than oceans,

N. Hemisphere more warming than S. Hemisphere.

Impact on human productivity.

With precipitation changes - reduce agricultural yields.

Question 58

Describe the impact of modern climate change -precipitation

Answer 58

Where temperature increase, then evaporation will increase, leading to precipitation increase. (Precipitation must balance evaporation).

1 degree celsius of global average warming = 3% increase in total global precipitation.

Increase not evenly distributed - regions that get a lot of rain will get wetter. Dry regions will get drier.

Higher fraction of total rainfall will come during heaviest rainfall - leading to flood events.

And increase in time between rain events - i.e increase occurrent of drought.

During winter - more rain than snow. leads to more water in winter and spring, and less in summer.

Question 59

Describe the impact of modern climate change -Sea level and Ocean Acidification.

Answer 59

Melting of grounded ice drive sea level rise. Already risen by 60mm/ 6cm.

AR(6) predicts by 2100, 44 to 76cm rise above today’s level.

For every degree of warming, estimated sea level rise of a few metres.

Because ice melts slowly, the few degrees of temperature increase locks us into many metres of sea level rise.

Ocean acidification - carbon dioxide converted into carbonic acid. Decreases pH affecting calcifying species.

Question 60

Describe the impact of modern climate change - Albedo Effect, Polar Amplification and Positive Feedback.

Answer 60

Decline in sea and land ice can amplify warming beyond the release of GHGs.

The amount of energy reflected by a surface is called albedo.

Ice is more reflective—it has a higher albedo—than the darker ocean or land.

Thus, previously ice-covered areas (where the ice has melted) will absorb more solar radiation, heating up the atmosphere, which in turn, melts more ice, exposing more dark areas and reducing the Earth’s overall albedo—the albedo effect.

This is the primary reason the Arctic is warming faster than other areas of Earth.

Other polar and geographic characteristics (e.g., more land and less ocean in the Arctic than the Antarctic) compound this effect.

This polar amplification leads to average Arctic temperature change 3-4 times that of the rest of the Northern Hemisphere.

The impacts of this amplification are manifold (faster melting of the Greenland ice sheet, leading to sea level rise; melting permafrost releases GHGs such as methane; and alteration of the northern hemisphere jet stream, affecting weather patterns across the globe).

Water vapor feedback, polar amplification, and any other self-reinforcing warming phenomena are “positive feedbacks.” A feedback loop either speeds up or slows down a change in a system.

As discussed, a positive feedback accelerates a change, in this case, warming. A negative feedback—such as a condition in which cloud cover accelerated, increasing albedo—would slow down warming.

However, negative feedback loops play less of a significant role in modern climate change than positive feedback loops. Feedback loops can play an important role in climate tipping points, discussed below.

(CH 1.9.4)

Question 61

Describe the impact of modern climate change - Extreme Weather Events.

Answer 61

Climate change is only one contributor to extreme weather events.

Extreme weather events are random in time.

Use extreme-event attribution science:

1. statistical analysis of historical climate - likelihood of extreme event could have occurred before human induced warming.

Note - this alone can’t tell us whether it’s caused by global warming. Correlation does not equate to causality.

2. physics of the phenomenon.
3. Computer simulations - run simulations with/ without increase in greenhouse gas to estimate the impact of climate change.

American Meteorological Society (AMETSOC) find that most extreme events have been affected by climate change.

(Ch 1.9.5)

Question 62

Describe the impact of modern climate change - on Human society and natural ecosystems.

Answer 62

human systems will respond to climate change. Natural ecosystems provide enormous benefit to human society - but the impacts will be more difficult to mitigate.

Risk of climate tipping point - climate system undergo a large/ rapid shift to new climate state.

eg, 12,000 years ago as Earth was emerging from ice age - temp in northern hemisphere dropped by several degrees in a few decades due to disruption in ocean currents.

experts think it is low probability, but could be catastrophic for human and natural systems.

potential abrupt changes include:

1. shutdown of Gulf Stream leading to widespread/ rapid climate changes
2. disintegration of west antarctic or Greenland ice sheets - raise sea level by several metres in a century or less.
3. thawing of permafrost/ methane hydrates - release large amounts of greenhouse cases - leading to additional warming and acceleration of climate change.
4. shift in timing/ magnitude of Indian monsoon - changing seasonal rainfall that people rely on.

Question 63

Define adaptation?
When is adaptation required? What systems will need to adapt?

Answer 63

Adaptation means responding to the negative impacts of climate change.

eg, build seawalls or relocate communities away from the encroaching sea.

any climate change that is not avoided must be adapted to.

even under most optimistic scenario - climate will continue to change for decades - therefore adaptation will be a necessary response.

Adaptation will be a primary response to physical climate risk.

adapt human built infrastructure or enhance ecosystem. includes adapting non-physical human systems (eg. communication, processes, regulations).

Can adapt individually or collectively - but typically require government action to organise and provide resources.

Adaptation raises issues of equity and justice due to need for significant resources. Could exacerbate existing inequalities.

(ch1.10)

Question 64

Define Maladaptation

Answer 64

When an intended adaptation action actually increases climate vulnerability.

eg. increase vulnerability (now, or in future), increase greenhouse cases, impose disproportional burden on most vulnerable.

(Ch 1.10.1)

Question 65

Define mitigation

Answer 65

Mitigation refers to a actions that reduce emissions of greenhouse cases, thereby preventing the climate from changing.

eg. policies that avoid or minimize climate change in the first place, thereby preventing impacts from occurring.

This is accomplished by reducing emissions of greenhouse gases, primarily through policies that encourage the transition from fossil fuels to energy sources that do not emit greenhouse gases.

Question 66

Define Carbon Intensity.

List the fossil fuels in order of highest of carbon intensity to lowers.

Answer 66

Amount of carbon dioxide produced per unit of energy generated.

g/ MMBtu
Kg/ MMBtu

of greenhouse cases - CO2, CH3, N2O

from highest carbon intensity to lowest:
1. Coal
2. Gasoline
3. Propane
4. Natural gas.

note: while natural gas appears cleaner than coal, methane leakage during extraction and transport of natural gas raises questions about value of natural gas as a bridge in transition to cleaner energy.

Question 67

Define geo engineering

Answer 67

Geoengineering refers to active manipulation of the climate system.

Under this approach, our society could continue adding greenhouse gases to the atmosphere, but we would intentionally change some other aspect of the climate system in order to cancel the warming effects of the greenhouse gases.

For example, we could engineer a decrease in the amount of solar energy absorbed by the Earth. If done correctly, this could stabilize the climate despite continuing emissions of greenhouse gases. In the rest of this chapter, we explore each of these options in detail.

Question 68

Explain how energy sources can contribute to or mitigate climate change

Answer 68

Ch 1.11

Question 69

Discuss mitigation opportunities, strategies, technologies and associated challenges

Answer 69

Replace fossil fuels with climate-safe energy sources.

1. Solar energy - need 1 million km2 of solar energy collectors to meet human energy needs. Approx 0.2% of earth’s surface or total areas of cities.
2. wind - intermittent. but can be put offshore where wind blows more consistently.
3. hydroelectric - most widespread dispatchable renewable energy today. provides 16% of world’s electricity. (but dams can cause environmental/ social problems).
4. Nuclear - mature tech, generates 10% of world’s electricity.
   Small Modular Reactors (SMRs) as an alternative
5. Geothermal - pump water underground, heated by earth, brought back to surface to turn turbine to generate power.
6. biomass- gross plants and burn them to yield energy. - requires land. clearing forests causes eco degradation and biodiversity loss.
7. Carbon capture utilisation and storage (CCUS) - burn fossil fuel in way that CO2 generated is not vented to atmosphere. But unclear if economically feasible at scale.
8. Battery energy storage system, (BESS) - short term storage (shirt energy to meet peak of demand) and long term storage (not feasible at scale at present) could displace need for dispatch able power.
9. hydrogen. (difficult to store/ risks), must be produced in ways that does not generate greenhouse case (such as electrolysis of water). Could be used in place of batteries.

Ch 1.11.1, 1.11.2

Question 70

Define despatch able sources of energy?

Answer 70

Able to generate energy regardless of weather conditions.

eg. Geothermal, Hydroelectric (most common 16%), nuclear (10%), biomass (problematic), CCUS (feasibility questions)

Question 71

What is geo-engineering?

Answer 71

Actively manipulating the climate system to prevent the climate from changing despite continuing greenhouse emissions.

2 main types:

1. Solar radiation management - reduce amount of solar energy absorbed by earth. (eg. inject sulphur into atmosphere, reach with water vapour to form droplets that reflect sunlight to space. problem is it can change precipitation patterns)
2. Carbon dioxide removal. (eg. planting trees to remove CO2 from air - problem is it is not a permanent storage).

Natural climate solutions.

Ch 1.12

Question 72

What are natural climate solutions to geo-engineering?

Answer 72

practices and technologies that can help sequester carbon from the atmosphere and reduce emissions, thereby reducing the impacts of climate change. These solutions often involve the conservation, restoration, and management of natural systems, such as forests, grasslands, and wetlands, which can absorb and store carbon dioxide. To the extent that they eliminate emissions, there is some ambiguity about whether these belong in mitigation or geoengineering

Question 73

What are carbon budgets and emission tragectories?

Answer 73

0.3-0.6°C for each Trillion tonne of CO2 emitted. Already added 2.2 trillion tonnes. so have 1.5 trillion tonnes left to stay under 2°C warming.

For 2°C threshold
- 1.5 trillion tonnes budget.
- reduce net emissions by 50% by mid 2040s and reach net zero by 2050

For 1.5°C threshold:
- 580 billion tonnes budget.
- reduce net emissions by 50% by mid 2030s and reach net zero by 2080

emissions become negative after reaching net zero.

Question 74

What are the key global emission limits, commitments and scenario paths?

Answer 74

2015 Paris Agreement - hold increase in global average temperatures to well below 2°C above pre-industrial levels” while “pursuing efforts to limit the temperature increase to 1.5°C above pre-industrial levels.”

Commitments to date:

US - cut greenhouse gas emissions by 50% below 2005 level by 2030, to achieve net zero by 2050.
- Infrastructure Investment and Jobs Act
- Inflation Reduction Act (invest $319 billion in provisions related to climate and clean energy).

EU - 55% below 1990 emissions by 2030m reach net-zero by 2050.

China - level of carbon emissions by 2030, reach net zero by 2060.

but not on track for Paris Agreement to limit global average temperate increase below 2°C above pre-industrial levels - instead expect 2.5 to 3°C of warming in 2100.