Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

ENVR200 > Lecture 13-16 > Flashcards

Lecture 13-16 Flashcards

1
Q

The greenhouse effect

A

Retention of solar energy in the form of heat
The result of GHG

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Greenhous gas GHG

A

Atmospheric gas which can absorb infrared radiation
Major elemental composition of Earth’s atmosphere
Methane, carbon dioxide, water vapour

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What type of light energy is involved in greenhouse effect

A

Shortwave radiation: visible light, has very short wavelength
- comes from the sun (some of this energy is absorbed and then reflected by the Earth
- process changes wavelengths from shorter visible light to longer infrared radiation

Infrared radiation: has longer wavelengths

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What kind of movements do two-atom gas molecules make?

A

Stretching
example: oxygen, nitrogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What kind of movements do >2 atom molecules make?

A

Stretching and bending

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Why does solar radiation pass through atmospheric gasses without interacting?

A

Neither bending or stretching vibrations fall within the same wavelength range as visible light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How do molecules interact with infrared radiation?

A

Bending vibrations are slower than strethcing vibrations

For some molecules, the rate of movement for bending vibrations can fall within the wavelength range of infrared radiation, hence interacting with infrared radiation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How do GHG absorb and radiate heat?

A

Infrared radiation interaction causes bending vibrations to move more vigorously

Some energy from infrared radiation is captured and then radiated outward
- Some to space, where it is lost
- Some back to the planet –> heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Examples of GHG

A

Water vapour
Carbon dioxide
Methane
Nitrous oxide
Chlorofluorocarbons (CFCs)
ozone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Who utilizes photosynthesis?

A

Autotrophs who acquire energy from sunlight

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Who utilizes cellular respiration?

A

Heterotrophs to derive energy from sugars
Autotrophs to use sugar energy fixed through photosynthesis

All large multicellular life requires aerobic cellular respiration in order to produce enough energy to support metabolism and growth (oxygen as an electron donor to produce energy)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How can species thrive in niches without the presence of oxygen and/or carbon?

A

Some forms of life can produce energy using different electron donors and acceptors

These alternative reactions produce less ATP than aerobic cellular respiration

Generally these types of energy acquisition are believed to have evolved before photosynthesis
- persist in environments devoid of sunlight and/or oxygen.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Chemoautotrophs

A

Life that uses inorganic substances as electron donors or acceptors other (exclude either carbon, oxygen or both)

Although chemoautotrophs are single-celled organisms, their impact on the global cycle of elements is significant
- Bacteria are the main driver of the global nitrogen cycle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are some reactions where molecules other than carbon are the electron donor (O2 is the electron acceptor)

A

Nitrification (nitrifying bacteria, e.g. in well-aerated soils)
Sulphur oxidation (sulphur-oxidizing bacteria)
Iron reduction
Methanogenesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How do species near deep sea hydrothermal vents get their energy?

A

Far from sunlight –> primary producers can’t use photosynthesis
Food chains for some persist mainly from the energy produced by sulfur oxidizing bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How do cows produce GHG

A

Enteric fermentation –> burps out methane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How do we compare GHG?

A

Two main metrics to compare the relative impact of a gas on the greenhouse effect:
1) Residence time (also called atmospheric time)
2) Global Warming Potential GWP (also called relative radiative forcing)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Residence time in relation to GHG

A

The amount of time a greenhouse gas remains in the atmosphere reservoir

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Global warming potential (GWP)

A

Measure the contribuation of a gas on global warming, using CO2 as a standard

For a given time period: how much infrared energy 1 ton of gas will absorb, compared to 1 ton of CO2 (often measured out of 100 years)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Why do we say that time period used to measure GWP can be deceiving depending on the residence time?

A

Divided over a longer time period, GWP seems smaller

Example methane:
- 25 to 28 GWP over 100 years
But residence time is only 10-12 years
Methane does most of its damage quickly then leaves
If measured on a 20 year time scale, GWP of methane=80.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the most impactful gases based on GWP, residence time, current atmospheric concentration and human influence?

A

Carbon dioxide: GHG with the higher concentration in the atmosphere presently

Methane: traps 25x more heat than CO2. Has the greatest future potential to impact global temperatures.

Nitrous oxide: has high GWP and residence time, and is released as a part of agriculture. Difficult to stop.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the natural sources of methane?

A

Methanogens
- Bacterial species (found in areas lacking oxygen)
- Animals which ferment their food during digestion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are some anthropogenic sources of methane?

A

Agriculture: animal husbandry (cows) and crops (rice in particular)

Energy: natural gas is mainly methane, processing of petroleum releases methane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Is atmospheric CH4 mainly antropogenic or natural?

A

60% anthropogenic
Rates of methane release have increased twice as fast as CO2 in the 20th century

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Does methane have a cycle?

A

Since methane is produce through biological processes it fluctuates seasonally similarly to CO2
When bacteria freezes, there is a drastic production in methane –> seasonal fluctuations

Depending on location, there is variation (how near to the equator –> less fluctuation)

Methane leaves the atmosphere mainly through reactions with OH- ions in the atmosphere
- Through a long series of reactions –> converts CH4 to CO2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

How does the cattle industry participate in methane production?

A

Major source
Methanogenesis takes place during the digestion of foods in ruminant mammals
High biomass of cows globally results in high impact

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Permafrost

A

Soil water which has remained frozen for a minimum of 2 continuous years

Decomposition in the absence of O2 –> methanogenesis (whereas in the presence of O2 –> respiration)

Every season, when a bit of the top layer defrosts, plants and soil microbes spring to life. Some of the permafrost melts

During the warm period, organic matter can build up (does not have the time to decompose fully)

Decomposing matter builds up over time

Complete melting of deep permafrost
- Rapid decomposition of stored organic matter (in absence of O2 in the soil –> produce methane and carbon dioxide)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What kind of feedback does melting permafrost engender with increasing atmospheric temperature?

A

Positive feedback between melting permaforst and increasing atmospheric temperature

Melting permafrost –> atmospheric GHG –> increasing temperatures

Estimated 1500 Gt methane and CO2 held in permafrost globally

Tipping point: we will not be able to stop the melting on permafrost

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Natural nitrous oxide

A

Natural part of the nitrogen cycle
- produced by bacteria in the soil
- Lightning breaking N3 bonds in the atmosphere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Anthropogenic contributions nitrous oxide

A

Produced as a byproduct of agriculture
- Nitrogen fertilizer used for crops feed bacteria, which produce more nitrous oxide

Less contributor to GHG, but increasing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

How is nitrous oxide removed from the atmosphere?

A

Removed by bacteria
breakdown by UV radiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

How to calculate residence time for excess CO2

A

R.T. (yrs)= excess C (GtC)/Net C(sink) (GtC/year)

This assumes a well mixed reservoir with a simple removal process

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Why does taking out excess CO2 from the atmosphere happen very slowly?

A

Because of the multiple layers of different sinks and linkages involved in taking out CO2 from the atmosphere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What is the relative impact of a specific gas on the greenhouse effect a result of?

A
  • The atmospheric concentration
  • The relative ability to absorb infrared radiation
  • The estimated residence time of a molecule in the atmosphere
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Climate trends definition

A

global temperature change over a set period of time (generally over long geological time periods)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Climate rhythms definition

A

Repeating cycles of climate (generally shorter on a geological timescale)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What is Earth’s climate defined by?

A

Global temperature averages (not weather patterns)
Climate vaires between hot and cold global averages

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Climate rhythms in recent history

A

Rapidly repeating rhythms of mild temperature changes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Ice Age

A

Persistent glaciers present

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Glacial period

A

Glaciers are growing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Interglacial period

A

Glaciers are receding
Currently in a warm interglacial period that began approx.11 000 years ago

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Hot House Earth

A

not persisten glaciers present
Last time planet was in this state was 50 million years ago

43
Q

Name three reasons that explain how Earth’s climate can move between extremes

A

Climate forcing
Feedbacks
Tipping points

44
Q

Climate forcings

A

Factors which have been shown to influence global climate

45
Q

Feedbacks

A

A process(es) which can amplify or dampen a climate forcing
Positive vs. negative
Lasting changes to global climate (change in a single process alone is NOT enough)
Most climate feedbacks are positive (easy for a small change in global temperatures to lead to a much greater global change)

46
Q

Tipping point

A

The physical or ecological state of an area (or the planet) crosses an “irreversible” threshold of climate forcings
Irreversible on a human timescale
On a geological timescale, all climatic changes on Earth to date have been shown to be reversible

47
Q

Does solar radiation change? If so, what are the processes driving this change?

A

Yes, the sun has a natural life span and has changed since it was formed, and will change in the future.

Processes driving change:
- Availability of hydrogen fuel
- Rate of burning for hydrogen fuel

48
Q

How does solar radiation work?

A

Hydrogen atoms in the sun forced together through intense pressure from gravity (fuse into helium, release energy)

Helium is heavier than hydrogen.
Increases pressure at the core. This increase in pressure increases the rate of hydrogen fusion –> more energy it will release

49
Q

Has solar luminosity increased or decreased since the sun formed?

A

33% increase in solar luminosity since the sun formed over 4 GYA
Increased in fuel consumption –> greater release of energy

50
Q

Has an increase in solar luminosity increased global temperatures?

A

Not a factor in modern rapid temperature increases

A major factor influencing global climate in the distant past (since there was considerably less energy reaching the surface of Earth. Less energy available to heat the planet)

51
Q

Has Earth’s atmosphere changed over time?

A

Major changes to types of gases found in the atmosphere since planetary formation. First atmosphere likely formed as gases released from cooling planetary rocks.

More recently, smaller scale fluctuations between concentrations of current gases

52
Q

How did the planet stay warm even if the sun was only producing 80% of the lumonisity it produces today?

A

SIgnificantly higher levels of atmospheric CO2 helped the planet stay warm, even with a lower solar radiation budget.

53
Q

What levels of O2, CH4, and CO2 were there in the early atmosphere (4 GYA)?

A

Lack of O2 (and O3)
High levels of CH4
High levels of CO2

54
Q

What was the birth of the organic carbon cycle?

A

Methanogens

55
Q

How did photosynthesis evolve?

A

Decreasing atmospheric CO2
Increasing atmospheric O2 (and O3)
Methane levels high

First photosynthesizers are bacteria (plants have not evolved yet)
- Cyanobacteria produce so much O2 as a waste product

56
Q

Why did methane suddenly decrease when oxygen became more prevalent in the atmosphere?

A

Methanogens can only live in oxygen-free environments
Methane reacts with oxygen and converts to CO2

57
Q

What happened to global temperatures when oxygen replaced methane and carbon dioxide in the atmosphere?

A

Significant decrease in temperature

58
Q

Huronian Glaciation

A

lasted over 300 million years
cycles of glacier and interglaical periods
possible snowball earth

59
Q

Ice-albedo feedback

A

Positive feedback between ice formation and increasing albedo lowering temperatures
Specific feedback system important to glacial growth and decline

60
Q

Continental drift

A

Tectonic plates move over geological time
Driven by geological processes producing new crust and recycling old crust

61
Q

What can the location of landmasses on the planet surface influence?

A

Temperature
- ocean currents
- solar radiation budget
- precipitation

62
Q

What impact does the movement of continents have on oceanic currents?

A

Redirect oceanic currents
Changing the direction of heat transfer
Eliminate heat transfer in a region

Example: 45 MYA South America connected to Antarctica
- 41-35 MYA Drake’s passage opened, isolating Antarctica current from nearby relatively warm current
- Glaciation of continent started 35 MYA

63
Q

Why is the albedo of Earth’s surface not equal?

A

Land reflects much more thermal energy than oceans

64
Q

Angle of insolation

A

Higher latitude: same solar luminosity spread out over larger area –> less energy per area of planet surface

Lower latitude: greater concentration of solar thermal energy per area of the Earth’s surface

65
Q

Why was there less energy available to transfer to areas of energy deficit in early Earth?

A

Mostly continents around the equator (as opposed to oceans). Greater reflection of thermal energy from within the critical zone of energy surplus

66
Q

How do plate tectonics produce new rocks?

A

Mountain-building events
Volcanic events

Brand new rocks: much greater amount of carbonate, calcium, and other minerals to weather in a (relatively) short time period

67
Q

Mountain-building events

A

Formation of new elevated regions of rock
- Can from at the convergent boundary of two different tectonic plates during continental drift (when two usually continental plates converge, rocsk at the collision zone are forced upwards
- Previously buried rocks now exposed to chemical weathering from rainfall

Can form from volcanic activity
- Flow of lava resulting in a new mountain formation
- Completely new minerals form from dyring lava (new rock exposed to the surface for chemical weathering)

68
Q

Is the location of mountain building events important?

A

Yes, greater impact on global climate if occurs within the equatorial region
More rainfall –> faster chemical weathering

69
Q

Cenozoic period

A

66 MY to today

Several mountain building events (increased chemical weathering transporting atmospheric CO2 to oceanic calcium carbonate)

Formation of Antarctic circumpolar current (formation of antarctic glaciers, increasing albedo)

Isthmus of Panama linked 2 MY
- creation of the gulf stream led to grater snowfall in Northern Europe and North America (increasing albedo) –> long term positive feedback

70
Q

Orbital processes and types of movement

A

Earth’s movement in space varies over time

Eccentricity
Obliquity (tilt angle)
Precession (tilt direction)

71
Q

Eccentricity

A

Changing distance between the sun and the Earth, as the Earth orbits the sun

Earth’s orbit is an ellipse
- Shape of ellipse changes between being more circular to more elliptical over 100 000 years (currently near mot circular)

72
Q

What does orbit path influences?

A

Length of seasons –> greater difference in length with eccentricity
Solar radiation on Earth –> at greater eccentricity, 23% difference between closest and farthest Earth orbit location

73
Q

Obliquity (tilt angle)

A

Earth roates on an angle which varies
Earth’s tilt creates differences in solar insolation seasonally (produces seasons)
Greater tilt –> grater extreme between seasons

74
Q

Precession (tilt direction)

A

Direction of the Earth’s tilt
- Points in one direction or the opposite direction
- Flips on a regular cycle of 23 000 years

Current direction of tilt
- Why seasonal extremes are milder in the winter Northern hemisphere, but more extreme during summer in the Southern hemisphere

75
Q

Milankovic Cycles

A

Obliquity, precession, eccentricity

All changes in Earth’s movement influence climate on predictable short geological time scales

Changes in amount and location of solar radiation on planet (solar radiation falling between 30-60 can differ by 25%)

Have acted as major climate forcings for 2 MY (during the Pleistocene)
- Pleistocene features a series of glacial and interglaical periods

Evidence: comparing the variation in insolation at 65% north in July as a baseline (variations coincide with periods of glaciation and interglacial periods)

Changes in insolation can cause changes in temperature –> need feedbacks to amplify small changes in temperature into climate change

76
Q

Low or high insolation during interglaical periods?

A

very high

77
Q

Low or high insolation during glacial periods

A

preceded by a period of excessively low insolation

78
Q

Proxy data

A

Data derived from sources that are not direct measurements of the variable of interest, but can be used to infer the measurements of the variable of interest

Long time scales (geological record)
Short time scalres (ice cores)

79
Q

Geological data

A

Evidence for past glaciation written in the landscape
- Glaciers carve out characteristic valleys in landscapes as they form
- Deposits left at the melting end of a glacier are characteristic

Glacial evidence persist over long time scales
- Knowledge of plate tectonic movement over geological time can be used to infer glacier extent over geological time

80
Q

How are glaciers formed?

A

By snowfall compressing over time and pressure
Atmospheric gases trapped in air pockets at the time of glacier formation

81
Q

Ice cores

A

Can be removed from old glaciers

Can provide a continuous snapshot of atmospheric gases as well as other events that leave atmospheric traces (such as volcanic eruptions)

Can also indicate global temperatures

Most common oxygen isotope is O16
- 1/1000 oxygen atoms has two extra neutrons (O18)
- Climate influences global temperatures as a reference, can be correlated to past global temperatures
(Going to lose O18 much more readily as oxygen moves north. What remains is composed mainly of O16).

82
Q

Is it harder for O18 or O16 to evaporate? What about precipitate as rainfall?

A

O18 harder to evaporate
O16 harder to precipitate

83
Q

Name some sources of information on past climates

A

Meteorological instrumented records: thermometer and barometer invented around the 17th century (most instrumental records date back to the 19th century)

Records intended for other purposes:
- private diaries, annals, chronicles with weather information.
- Shipping logs (documenting winds), tax records (e.g. explanations due to bad=good crops), newspaper records
- Crops production, pricing records (wheat, grapes), dates of natural phenomena

Clues in the natural worlds:
- ice cores, coral cores, sediments from oceans or lakes, fossil remains
- tree rings (darker and lighter bands; one is spring growth and the other is summer growth gives clues to humidity at the time)
- pollen (look in sediments to see what kind of pollen was around –> indicates what type of species was present)

84
Q

Carbon dating

A

Most isotopes tend to be unstable (decays over time) –> half life
C14 forms high up in the atmosphere, decays into C12 –> measure the ratio, you can estimate the age

85
Q

Is oxygen useful for dating?

A

No, O16 and O18 is stable isotopes, and stay as such forever (relative concentration does not change with time)
Not useful for dating, but rather used to analyze (since different isotopes behave or react differently)

86
Q

Ice-preserved clues of temperature

A

Evaporation requires energy
Heavier water is harder to evaporate
If it is colder (less energy available), evaporating lighter water is preferred

O18 and O16 in ice is a function of ocean temperature and global ice amount. Therefore, we have a paleo thermometer
Ratio of O18 and O16 gives you clues to the temperature at the time
- Snow that is particularly poor in O18 –> evaporated in cool conditions
- Higher concentration of O18 –> higher temperature
- O16 evaporates easier (and precipitates) (less O16 in the water), which leads to O18 remaining in the water and O16 in glaciers

87
Q

Ice preserved gas concentrations

A

Gases are trapped in the ice and can be quantified

88
Q

How can we use corals to measure temperature?

A

Corals have O18 and O16 changes due to water temperatures

89
Q

When was the last glacial maximum

A

18 000 years ago
A lot of ice –> sea levels decreased

90
Q

How did we get out of the last ice age?

A

After nearly 100 000 years of an ice age that peaked 18 000 years ago, a boost in solar illumination in the Northern latitudes helped melt all ice
More sunlight –> warmer summers, snowline makes it to the North, ice albedo feedback –> ice recedes

91
Q

What has changed since the last ice age?

A

+5 degrees celcius
Warming temperatures (Earth was colder and drier before) and changing precipitation patterns (as ice starts to melt, more water availability)

Appearance and disappearnace of many great lakes in temperature and lower latitudes

Changing vegetation

Changing sea levels (ice melts, sea rises)

Flooding of low-level areas (Mediterranean basin, Black Sea)

92
Q

What have ice records revealed about temperature since the last ice age?

A

Temperatures have risen irregularly
Temperatures have remained relatively stead for the past 10 000 years, maybe decreasing slightly in the past 2000 years

Some suggest that ancient farming followed by the industrial age have delayed the impensing glaciation

There are evidences of accasional rapid climatic transitions in the past 15 000 years (because of positive feedbacks, the climate system can change very rapidly)

93
Q

What is the 8.2 ka event?

A

Drained of Lake Agassiz
Lake drained into bay –> drop in temperature

94
Q

How do we build forecast tools?

A

Process called system modeling:

1) We must determine all the factors that influence what one is trying to forecast

2) We need to quantify how the interactions occur (interaction/behaviour equations). These interactions are then expressed as mathematical equations describing how each quantity varies with time.

3) We often must estimate the initial conditions (or starting values) of the different relevant factors.

4) We then solve these mathematical equations

95
Q

How do we model systems with feedbacks?

A

Systems with feedbacks often have time-dependent behaviour
Modeling requires solving for time-depending interactions

COmplex systems that are irregularly perturbed externally (no stead state) are extremely difficult to predict

96
Q

What are some forcings that currently change climate?

A

Changes in GHG (such as those recorded in ice cores)

Fluctuations in solar energy: the 11 year cycle and longer-term variations
- Magnetic poles flip every 11 years. This is associated with change of activities. Monitor this by the observations of sun spots (more sunspots=sun is more active=sends more energy)

Eruptions, sending aerosols in the stratosphere that scatter solar radiation, change atmospheric chemisry (reflects radiation, changes the chemistry by bringing sulfate)
- Dust spreading
- Temperatures can diminish (ex. after Pinatubo)

Sea salts: waves crash, salt it lifted in the atmosphere

Strong winds in deserts: brings dust in the atmosphere, brought very long distances, settles in oceans and brings minerals to phytoplankton

Smoke from fire (deforestation, agricultural practices): dust stays in lower atmosphere, gets flushed by rain. When the dust reaches the stratosphere, it has an effect on climate for a longer time

97
Q

What is responsible for a 5-10% of the warming observed in the 20th century?

A

Solar illumination

98
Q

What does a change in aerosol and cloudiness do to climate?

A

Competing reflectance vs. greenhouse effect:

  • If you add more aerosols, more light scatters (cooling effects)
  • More aerosols means more cloud droplets –> smaller clouds –> more surface area –> reflects more (cooling effect)
  • Smaller droplets –> longer to rain, cloud lasts longer and grows taller (both warming and cooling effect)
  • Warmer air –> less relative humidity –> less clouds
99
Q

Global climate models (GMC)

A

Large computer program which mathematically represents complex interactive processes of climate systems
- Components including atmosphere, ocean, land surface, sea-ice, etc.
- Based on physical laws (e.g. Newton’s equation of motion)
- Most sophisticated models available to study climate variability and climate change

Based on a series of equations based on the laws of physics, motion and chemistry.
The Earth is divided into a 3D grid with each grid containing a set of initial conditions (T, pressure, wind speed and direction chemical composition)

Equations try to predict the changes in the conditions within and between the grids when external inputs are introduced into the model. Feedbacks have to be included

100
Q

What is the difference in forecasting climate vs. weather?

A

Atmosphere is either unstble or at the brink of instability (where positive feedbacks dominate)
- Small air flow pertubations grow to become planet-wide (chaos theory, butterfly effect)

Climate deals with averages and is more stable thanks to some strong negative feedback processes or processes with limited feedbacks
- Radiative cooling feedback
- Chemical weathering (long-term inorganic C cycle)

Climate is less unpredictable than weather

101
Q

Validation of GCMS

A

Ability to reproduce past/present-day patterns of temperature, precipitation and their seasonality and recent changes

Cooling effect of aerosols (through scattering of solar radiation) is important to capture recent temperature variability

102
Q

Climate change experiments with GCMs

A

After validation, numerical experiments can be performed (example: by increasing concentrations of GHG, etc. for the new century)

Scenario of future human activity –> future emissions of GHG –> Earth system models –> climate change preditictions –> impact models –> ecosystem, economical, and sociological consequences

103
Q

What is a climate change prediction in 2100?

A

3 degrees celcius increase globally

But more over land than over water
More at high latitudes and in winter than at low latitudes or in summer
More at night than during the day

104
Q

Why do we use global climate models?

A

Given all the interactions in the cliamte system, the question is approached by computer modeling

Despite their limitations (computer power, knowledge), these physically-based models have been reasonably successful at modeling the present; most researchers believe they are satisfactory tools

They confirm man’s present influence on climate

They make predictions of significant warming before the end of the century

ENVR200 (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions