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describe the quaternary period
started 2.6 million years ago
contained two epochs:
the holocene and the pleistocene
these epochs contained both colder glacials,
where ice advanced from the poles
and warmer inter-glacials,
where ice retreated
however, the quaternary period is known overall as an ice age
state ice age definition
where there is
permanent snow and ice on the planet
at both poles
describe climate change in the pleistocene epoch
this epoch was dominated by ice ages
where large ice sheets covered vast areas of North America, Europe and Asia
these glacial periods were broken up by warmer inter-glacial periods
within this epoch, the most recent glacial maximum occurred
after which temperatures began to rise
the transition between periods was influenced by factors such as the Milankovitch cycle
causing alternating humid and arid weather conditions
with these fluctuations being more pronounced in the middle and late pleistocene
state how long the pleistocene epoch lasted
started 2.6 million years ago
ended 11,700 years ago
describe climate change in the holocene epoch
during the early holocene, the climate was warmer and more humid than it is today
occurring in the holocene climate optimum
which occurred roughly 9,500-5,500 years ago
with a thermal maximum occurring 8,000 years ago
where global temperatures increased
the mid-late holocene saw a gradual cooling
with the 8.2-kiloyear event occurring 400 years ago
causing a brief, but intense cold spell
the Little Ice age also occurred in the holocene
state how long the holocene epoch has lasted
started 11,700 years ago
ongoing period
state the dates of the medieval warm period
950 AD - 1250 AD
describe climate change in the medieval warm period
period experienced warmer temperatures
especially in the North Atlantic region
caused by increased sunspot activity
as sunspots on earth’s surface have a lower albedo
causing them to absorb more infrared radiation from the sun
causing an increase in surface temperature
changes in ocean currents
as ocean currents are vital for the redistribution of warm water across the globe
and decreasing volcanic activity
which reduced the amount of volcanic ash being deposited in the atmosphere
meaning more solar radiation could enter earth’s atmosphere
describe the impacts of the medieval warm period
warmer climate allowed for longer growing seasons
leading to increased agricultural activity globally, but particularly in Europe
and increased biodiversity as the warmer climate allowed for new crops to grow that could not previously be cultivated
also caused population growth through improved agricultural yield
contributing to the development of settlements and trade networks
key data for the medieval warm period
1000 - 1300 was a period of stability, peace and prosperity called the ‘High Middle Ages’
huge famines cover Europe and North America, with the Great Famine of 1315-1320 seeing some Europeans resorting to cannibalism
the Black Death outbreak of the mid 1300s killed approx. 75 million people, where experts have linked these morality rates to the weakened immune systems caused by the colder climates in this era
there was a lack of volcanic activity between 900 AD - 1100 AD
state the dates of the little ice age
1200 - 1700 AD
describe climate change in the little ice age
temperatures were 1°C lower than present day
with permanent ice at both the geographical north and south poles
little ice age was caused by
a decrease in sunspot activity
as sunspots on earth’s surface have a low albedo
meaning they will absorb more infrared radiation from the sun
making temperatures on earth warmer
increased volcanic activity
as volcanic eruptions release ash clouds
which pollute earth’s atmosphere
preventing solar radiation from entering earth’s atmosphere
making earth’s temperatures colder
and changes in ocean current patterns
as currents are crucial in regulating temperatures and weather patterns globally
describe the impacts of the little ice age
cooler temperatures led to shorter growing seasons
resulting in crop failures and food shortages on a large spatial scale
which had significant socioeconomic impacts
as it increased chances of famine occurring and mortality rates globally
also caused significant glacial expansion
which is documented through historical records and physical evidence
also caused cultural responses
through contemporary literature and art in the period
which often depicts harsh winter scenes, reflecting the colder climate
key data for the little ice age
there was a ‘Frost Fair’ on the Thames in London in 1685, where people set up stalls on the ice across the river and played games
several major volcanic events occurred in the 1200s.covering the sky in ash and causing arctic sea-ice to thicken
the Maunder Minimum is a period in the late 17th and early 18th century where sunspots became incredibly rare
state the dates of the modern warming
1760 AD - present
describe climate change in the modern warming
this era is experiencing a significant increase in global temperatures
caused by human activities such as
the increased combustion of fossil fuels releasing large amounts of polluting greenhouse gases into the atmosphere
causing temperature increases as these gases absorb and re-emit solar radiation back to earth’s surface
also caused by increased deforestation, as trees absorb large concentrations of carbon dioxide
meaning deforestation has led to a decrease in carbon storage capacity
and a decrease in biodiversity in these areas due to the disruption of local ecosystems
also caused by agricultural practices such as the use of fertilisers and livestock
contributes to greenhouse gas emissions
as livestock and rice paddies release large concentrations of methane into the atmosphere
describe impacts of modern warming
causes melting ice caps and glaciers which contributes to increasing sea levels
increasing rates of water-influenced natural disasters and coastal erosion
causes increase in risk of severe heat waves
which are influenced by an increase in temperature
causes increase in the intensity and frequency of storms, hurricanes and heavy rainfall events
which can result in increased flooding, damage to infrastructure and increased mortality rates
as increased ocean temperatures causes increases evaporation
causes ecosystem disruption
as many species are unable to survive the rapid changes in climate
causing some species to go extinct, decreasing biodiversity and ecosystem equilibrium
causes changes in agricultural patterns
as climate change causes temperatures and precipitation rates to fluctuate
meaning some areas will experience lower crop yields
leading to food security issues in these areas
key data for the modern warming
in 1927, earth’s population was 2 billion. By 2011, there were 7 billion, caused by increase in agricultural activity, resulting in a vast increase in human-induced greenhouse emissions
96% of glaciers around the world are retreating
Industrial Revolution began in the early 1800s
describe how variations in energy from the sun is evidence for climate change
increased sunspot activity increases earth’s surface temperatures
due to their lower albedo absorbing more solar radiation
time periods where there is increased sunspot activity will experience warmer climates
the number of sunspots on the sun’s surface is not constant over time, however it appears to follow a fairly even cycle in fluctuation over time, where sunspot activity seems to peak approx. every 11 years
modern warming period is currently experiencing a sunspot maximum, due to increasing solar irradiance (causes sunspots)
state sunspot definition
region on the sun’s surface
that are temporarily cooler
making them appear darker
than surrounding regions
state solar flare definition
brief eruption
of intense high-energy radiation
from the sun’s surface
associated with sunspots
describe how global temperature data is evidence for climate change
global temperature data demonstrates fluctuations in global temperatures, allowing for temperature patterns to be observed
this data can be used to cross-reference past and present climate events to demonstrate the effect of temperature on the climate
key data from global temperature data
temperature records date back to 1880, due to a lack of measuring equipment before this
from 1880-2000, global temperature has increased by 0.85 degrees C
describe how global temperature data is collected in LIDCs
fewer readings
as LIDCs lack the advanced equipment
to measure temperature readings
describe how global temperature data is collected in Antarctica
no readings
as Antarctica is vastly unpopulated
thus readings are only measured by the select few of scientists living there
describe how global temperature data is collected in oceans
fewer readings
due to technological limitations
caused by a lack of technological advancements
in marine measuring equipment
evaluate global temperature data as evidence for climate change
D - some areas of the world have fewer readings than others
A - technology has advanced rapidly, so thermometers are cheap and easy to obtain
describe how ice cores are evidence for climate change
ice cores are drilled cylinders of ice
that stretch from the bottom of the ice sheet to its surface
bubbles of greenhouse gases are trapped in older ice
and the abundance of these bubbles can be measured
to determine the composition of the atmosphere at the time of the ice layer’s creation
also linking temperatures to the concentration of greenhouse gases in specific time periods
state timescale of ice cores
1150 AD - present
evaluate ice cores as evidence for climate change
A - global atmosphere mixes very quickly and thus data reflects a good global average
D - there are only a few places globally where ice cores can be extracted
D - extracting ice cores is expensive and time consuming
describe how tree rings are evidence for climate change
annules tell history of wet years and dry years
as each annules is one year of growth
with the width of annules changes based on climate fluctuations
with thick rings indicating a hot and wet climate that year
and thin rings indicating a cold and dry climate that year
state the timescale of tree rings
oldest tree is 4,000 years old
evaluate tree rings as evidence for climate change
D - hard to know the exact cause that resulted in annule changes
A - annules give us an indication of local climate, so we can look at local change, which isn’t possible with ice cores
describe historical data as evidence for climate change
maritime records, paintings and literature
provide insights about past weather patterns and climate changes experienced
from knowing the causes of changes in weather patterns
scientists can calibrate climate models
and predict global temperature changes
key data for historical records
painting of central London in 1684 demonstrates
that ice and snow were present, as the Thames was iced-over
meaning colder temperatures were present in winter
an abundance of clouds and fog are portrayed in the painting
meaning London was receiving less solar radiation
causing colder temperatures
state timescale of historical records
ancient cave paintings in France and Spain date back to 40,000 years ago
but written evidence is more recent
evaluate historical records as evidence for climate change
D - we’ll never know whether the producers of the records were exaggerating weather and climate
A - the most frequent painting styles in certain eras was realism so exaggerations of weather were unlikely
describe how variations in energy from the sun caused climate change
solar irradiance varies through an 11-year solar cycle
causing a fluctuation in sunspot activity
when solar output is higher, more solar irradiance reaches the earth
this increased solar irradiance causes changes to the global atmospheric circulation, affecting weather patterns and the climate
as solar irradiance increases, a sunspot maximum is entered
the sunspot maximum can lead to an increased possibility of solar flares
which causes a brief eruption of intense, high-energy radiation from the sun’s surface
however when solar output is lower, less solar irradiance reaches the earth
this can cause climate change-induced events such glacial periods
with lower temperatures
sunspot definition
regions on the sun’s surface
that are temporarily cooler
making them appear darker
than the surrounding regions
describe how the earth’s eccentricity causes climate change
the earth’s orbit around the sun is elliptical
over time, the orbit fluctuates from being more elliptical to more circular
caused by the gravitational pull of Jupiter and Saturn
when the earth’s orbit is elliptical, the earth spends less time close to the sun in the span of a single year
this means we receive less solar irradiance over the year
causing the earth to cool
describe how the earth’s obliquity causes climate change
earth is tiled on its axis at approx. 23.5°
because of the collisions earth suffered in its formation when small ‘planetesimals’ coalesced to form the earth
the earth’s obliquity ranges between 21.5° - 24.5°
the earth’s obliquity fluctuates over a cycle period of 41,000 years
a smaller tilt causes less noticeable seasons
less noticeable seasons in high latitudes means no spring or summer melt
so more ice and snow forms
causing temperatures to drop
describe how volcanic activity causes climate change
increasing volcanic activity decreases average temperatures
as the eruption injects ash and gases into the atmosphere
which act as pollutants
meaning more solar irradiance is reflected back into space
and less solar irradiance reaching earth’s surface
describe an EXAMPLE of how volcanic activity causes climate change
eruption = Pinatubo
date = June 15th, 1991
size = VEI 6
impacts:
tiny aerosol droplets released in the explosion reflected sunlight away from earth, cooling global temperatures
ash was released 14km into the air
15 million tonnes of sulfur dioxide was injected into the atmosphere
caused a 0.5°C decrease in earth’s surface temperature
describe how human activity causes climate change
FOSSIL FUELS
humans have increased the combustion of fossil fuels
to generate energy
the combustion of fossil fuels emits carbon dioxide
which pollutes the atmosphere and enhances the greenhouse effect
reflecting solar irradiance back into space
meaning less reaches the earth’s surface
causing lower average surface temperatures
LIVESTOCK
global human populations have been increasing
causing an increase in demand for food resources, especially animal products
rearing livestock is extremely energy-intensive
producing one steak uses 113,000 kJ
livestock also produce methane, which pollutes the atmosphere and enhances the greenhouse effect
explain how climate change causes sea levels to rise
we are currently in an glacial period, with permanent ice at both geographical poles
an impact of climate change is rising global temperatures
these increased temperatures melt the glaciers and ice at the poles
causing more water to enter oceans
causing sea levels to rise
explain how climate change causes drought
an impact of climate change is rising global temperatures
the rising global temperatures affects the global water distribution system
as it increases evaporation in some areas
causing other areas to receive less rainfall
which both increase risks of drought
as there is not enough water to permeate the soil
and replenish water sources such as lakes
explain how climate change causes population migration
climate changes increases the frequency and intensity of natural disasters
such as floods and hurricanes
which can cause damage to urban settlements
making places uninhabitable
resulting in people having to move to survive
explain how climate change causes coral reef bleaching
an impact of climate change is a rising global temperature
which has increased the average temperature of oceans
coral reef bleaching is caused when ocean temperatures rise over one degree more than average
causing the coral to bleach white, causing it to not be able to photosynthesise and die
explain how climate change causes forest fires
an impact of climate change is a rising global temperature
causing severe droughts in some areas
which dries out vegetation and soil
which acts as kindling to start and spread forest fires
describe the climatic region ±90° latitude
polar climate
cold and dry
extremely low temperatures
most precipitation falls as snow
describe the climatic region ±60° latitude
temperate climate
cold and wet
experiences significant seasonal variations in temperature
moderate rainfall
frontal rain occurs here
describe the climatic region ±30° latitude
desert
hot and dry
very low rainfall
extreme diurnal range (temperature variations between day and night)
describe the climatic region 0° latitude
tropical rainforest
hot and wet
convectional rainfall occurs
extremely high rainfall
high temperatures annually
explain how the global atmospheric circulation is controlled by movement of air between the poles and the equator
equator (0°)
warm air is distributed here by the Hadley Cell
warm air rises, creating a band of low pressure
the air cools as it rises, condensing to form convectional rainfall
desert (±30°)
cool air is distributed here by the Hadley Cell
cool air sinks, creating a band of high pressure
the air warms and becomes drier as it sinks
temperate (±60°)
warm air is distributed here by the Ferel Cell
warm air rises, creating a band of low pressure
the air cools as it rises, condensing to form frontal rainfall
polar (±90°)
cool air is distributed here by the Polar Cell
cool air sinks, creating a band of high pressure
explain how the global atmospheric circulation leads to extreme weather conditions
Oymyakon (COLDEST)
average temperatures = -40°C
lowest temperature = -71°C
close to 90° latitude, meaning dense cool air distributed by the Polar Cell sinks here
causing bands of high pressure
due to the lack of solar irradiance the area receives, temperature remains colder year around
caused by the earth’s obliquity
creating a cold, dry climate
Lut Desert (HOTTEST)
highest temperature = 70.7°C
15°-30° N, meaning dense cool air distributed by the Hadley Cell sinks here
causing bands of high pressure
due to the increased solar irradiance the area receives, temperature remain extremely high all year around
caused by the earth’s obliquity
creating a hot, dry climate
Atacama Desert (DRIEST)
longest dry streak = 173 months
average rainfall = 1-3mm annually
15°-30° S, meaning dense cool air distributed by the Hadley Cell sinks here
causing bands of high pressure
due to the increased solar irradiance the area receives, temperature remain extremely high all year around
creating a hot, dry climate
Ureca (WETTEST)
average rainfall = 1024mm annually
0°-15° N, meaning light warm air distributed by the Hadley Cell rises here
causing bands of low pressure
as the air rises, it cools and condenses to form convectional rainfall
due to the increased solar irradiance the area receives, temperature remain extremely high all year around
creating a hot, dry climate
Antarctica (WINDIEST)
highest average hourly wind speed = 199mph
cold dense air distributed by the Polar Cell flows downhill from inland areas to coastal areas
the GPE of the wind causes high velocities as the wind travels downhill
these winds are called Katabatic winds
explain how low precipitation causes drought
caused by changes in weather patterns
which prolong high-pressure systems in areas
inhibiting cloud and precipitation formation
explain how high temperatures causes drought
increased temperature increases evaporation rates from the soil and water bodies
reducing water available
explain how deforestation causes drought
trees return water to the atmosphere by transpiration
deforestation decreases rates of transpiration in local areas
meaning there is less water available to be distributed
describe the distribution of droughts experienced globally
SUB-TROPICAL REGIONS
20°-30° latitude
locations: US, Mexico
these regions experience high temperatures and low rainfall
prolonged high-pressure systems here cause dry spells
DESERT REGIONS
locations: Sahara Desert, Atacama Desert
these areas are naturally arid, tending to receive less ~250mm of rainfall annually
the drought is caused by the low moisture levels
SEMI-ARID REGIONS
locations: Sahel, Australia
face significant dry periods due to increased rates of evaporation
describe the global change over time in frequency of droughts
PRE-20TH CENTURY
droughts less frequent than 21st century
droughts largely undocumented due to insufficient technology
droughts experienced due to natural climate variability
no long-term significant impacts of droughts
21ST CENTURY
frequency is INCREASING
induced by climate change
which alters precipitation patterns
and increases evaporation rates
state conditions required for tropical storms
ocean temperatures: 26°C-27°C
water depth: 60m +
winds: converging
why does tropical storm formation vary in which month it happens
earth’s global temperatures vary based on its obliquity
which affects the amount of solar insolation it receives
in northern hemisphere, tropical storms are more likely to form in summer
as these times have increased ocean temperatures
caused by increased solar insolation
which countries aren’t affected by tropical storms
West Africa
Southwestern America
explain why west Africa and southwestern America aren’t affected by tropical storms
these regions receive cold ocean currents
warm ocean currents are required to form tropical storms
explain what is going to happen to the intensity of tropical storms in the future
increase
due to increasing global temperatures
creating warmer ocean currents for longer periods of time
explain what is going to happen to the frequency of tropical storms in the future
increase
due to increasing global temperatures
creating warmer ocean currents for longer periods of time
describe the change over time in the frequency of tropical storms
POST-1970S
observable increase in frequency and intensity of tropical storms
number of CAT 4 and 5 tropical storms occurring increased at this time
2000s-PRESENT
frequency and intensity of tropical storms had continued to increase
explain how El Nino leads to drought in Australia
weakened trade winds means warm water is distributed from South America to the Central Pacific Ocean instead of Australia
this causes warm air to rise above the ocean instead of above Australia
meaning cold, dense air is circulated to Australia, causing bands of high pressure
these prolonged high-pressure systems inhibits precipitation formations
decreasing moisture levels
describe how the Big Dry, 2017-2019, affected Australian people
majority of the area affected was farmland
especially areas in New South Wales and Queensland
lots of livestock died or had to be killed during the Big Dry as the food they would normally eat wasn’t available because of drought
one cattle farmer had to kill 80+ cattle due to this
the prices of cotton increased from AUS $200 → AUS $700 in the first 6 months of 2018
this caused severe impacts on farmers’ mental health
many small businesses had to close due to the cost of living crisis the drought caused, as many people didn’t have the disposable income to spend
national wages decrease by 1%
many people lost their jobs
50,000 jobs in NSW were lost, 2017-2019
describe how the Big Dry, 2017-2019, affected the Australian environment
AQUATIC ECOSYTEMS
reduced water flow led to increased salinity in fresh water sources
aquatic species that relied on the freshwater environment were harmed
DECREASED BIODIVERSITY
reduced water flow led to plants dying as they were unable to photosynthesise
many animals were unable to survive without sufficient water availability
2019 - % of threatened species increased by 14%
describe the ways individual farmers adapted to drought
developing technology and sharing data
to adapt their farming mechanisms to drought conditions
changing ploughing techniques to reduce soil being blown away using GPS mapping
planting more heat-intolerant crops, such as chickpeas and fava beans
describe the ways the Community Women’s Association (CWA) adapted to drought
raised AUS $105,000 for the ‘Help a Farmer’ Christmas campaigning
donated 1,000 hampers to farmers in need
delivered AUS $27,0000 worth of gift cards to farmers in need
describe the ways desalination plants adapted to drought
supplied more water to the population during times of drought by desalinating sea water
cost AUS $1.9 billion to build
costs AUS $195 million per year when its closed
