Download Geography – Book 7

7.1: General Global Warming Facts
(I) Introduction
- Global warming is an increase in global average temperature
- Since 1850, it increased by around 0.74˚C
- IPCC, UNEP & WMO agree on global warming
- Number of cold nights & days decreasing
- Ocean temperatures increasing
- Extent of sea ice cover, glaciers & ice caps are shrinking
- Global average sea level has risen
(II) Controversy
-
Some argue it is fiction as fluctuation is normal & today is just part
of a long-term fluctuation
There is lack of precise climatic data (Accurate air temperature data
only goes back around 100 years)
(III) Weather & climate
- Weather is conditions at the lowest layer of atmosphere at a
specific time
- Climate is average weather conditions over many years
7.2: Insolation & Global Temperature
(I) Basics
- Insolation (incoming solar radiation) is solar radiation received
in the atmosphere / earth's surface
- It leads to complex air temperature patterns
- Increasing altitude --> declining insolation
(II) Factors affecting insolation
1. Angle of the Sun:
A. Basics:
o Refers to angle at which sunlight strikes the earth's surface
o At 90˚, the overhead sun (only in equinoxes at the Equator)
--> most intense insolation
o Smaller angles --> more spread out sun rays (less insolation)
B. Latitude:
o Angle is larger in low-latitude regions (30˚N~30˚S)
o Larger concentration --> stronger insolation
o Angle is smaller in middle- & high-latitude regions
(30˚-60˚N & S; 60˚-90˚N & S) --> weaker insolation
C. Time of Day:
o Angle of sun increases at sunrise, peaks at noon (midday sun),
& decreases at sunset
D. Season:
o Earth revolves around the Sun
o Earth is tilted at 23.5˚ to the vertical
o Resulting in different angles of the sun at different times
o #Hemispheres should also be taken into account
2. Daylight Duration:
- Longer durations --> more insolation (usually measured in hours)
3. Atmosphere:
-
Atmosphere affects amount of solar radiation reaching the surface
Dust particles, gas molecules & clouds in the atmosphere reflect,
absorb / scatter solar radiation
Maximum insolation is not in the Equator, but 23.5˚N & S
Due to high equatorial cloud cover that reflects solar radiation
Drier climate & less cloud cover at 23.5˚N & S --> highest
amount of insolation (i.e. Sahara Desert)
(III) Insolation's relation to global temperature distribution
1. Transferring Process of Energy into the Atmosphere:
- Insolation absorbed by the surface is released into the atmosphere
- It is transferred via radiation, conduction & convection
o Radiation; heat loss via long wave radiation
o Conduction; air particles transmit heat when moving over the
surface
o Convection; convection currents (hot air rises, cold air sinks)
- Amount of heat in atmosphere measured by thermometers (readings
are called air temperature)
- Temperature data includes:
o Daily, monthly & annual mean temperature: average of
"highest & lowest", "daily mean" & "monthly mean" respectively
o Daily & annual range of temperature: difference between
highest & lowest "daily temp." & "monthly mean" respectively
2. Relation between Insolation & Air Temperature:
- Higher insolation --> higher air temperature
- Noon's highest insolation --> max air temperature 1-2 hours later
- ^It takes time for heat to be transferred from the surface to the air
- No insolation after sunset --> air loses more heat that it receives
- Above concepts are applicable to different seasons
(IV) More on temperature patterns
1. World Distribution of Temperature Patterns:
- Isotherms are lines joining places with the same mean temperature
- Isotherm maps show temperature distribution patterns over an area
o Curves; variation of air temperature at certain latitudes
o Close spaces; large air temperature variation
o Open spaces; small air temperature variation
- Air temperature is higher in low-latitude regions
- Winter temperature variation in the Northern Hemisphere is higher
- Places at the same latitude may have different air temperatures
- There is seasonal pattern in air temperature
2. Factors Affecting Global Temperature Patterns:
A. Insolation:
o All insolation factors (part II) also influence air temperature
B. Land & Sea:
o Isotherms over the land bend polewards in summer &
equatorwards in winter
o They do not share same temperatures even in same latitudes
Heat transfers quicker on land via conduction
Ocean water is heated by convection (which transfers slower)
Inland areas have larger annual temperature ranges
Coastal areas have smaller annual temperature ranges
Continental climate developed in the continental interior
Maritime climate is strongly affected by ocean conditions
Annual temperature range increases with latitude &
distance from sea
o Continental area is larger in Northern Hemisphere --> annual
temperature range varies more
o
o
o
o
o
o
o
3. Factors Affecting Local Temperature Patterns:
A. Winds:
o Have seasonal patterns
o Split into onshore & offshore winds
B. Ocean Currents:
o Refers to seawater flowing along fixed routes
o Poleward flows are warm currents
o Equatorward flows are cold currents
o When warm currents flow into colder areas, the air above
becomes warm as well, bringing warmth to the area
o Places with warm currents have higher temperatures
C. Aspect:
o Refers to direction a slope faces in relation to the Sun
o Northern Hemisphere south-facing slopes strike larger angles,
receive more insolation & are warmer than north-facing slopes
D. Altitude:
o Lowland has denser air & therefore warmer air temperature
o Higher altitudes have less dense air & colder air temperature
o The environmental lapse rate is 6˚C/1000m
E. Cloud Cover:
o Thicker cloud covers --> larger reflection & insolation loss
o ^These areas have lower daytime temperatures
o Cloud covers absorb heat released from the surface
o Air temperature does not drop significantly at night
o Places without them have huge daily temperature ranges
o ^i.e. 58˚C in the Sahara Desert
7.3: Global Warming Causes
(I) The greenhouse effect
1. Basics:
- Greenhouse gases act as blankets keeping the lower atmosphere warm
- Incoming & outgoing radiation have been at balance at
- The Earth's average temperature is 15˚C before the 19th Century
- Greenhouse gases block long wave radiation from leaving the earth
2. Carbon Dioxide (CO2):
- Principal greenhouse gas
- CO2 moves in a carbon cycle:
o Released naturally from human & animal respiration
o Captured, transformed & stored in plants & oceans via
photosynthesis after reaching the atmosphere
3. Methane(CH4):
- When plants decompose in areas with insufficient oxygen
- Produced naturally in wetlands & oceans
4. Nitrous Oxide(N20):
- Released naturally from oceans & bacteria in soils
(II) Human factors
1. Burning Fossil Fuels:
- Atmospheric CO2 increased over 32% since 1750
- ~75% of human-induced CO2 emissions are from burning fossil fuels
- Burned mostly in factories, power plants & vehicles
2. Deforestation:
- Burning process releases CO2
- Fewer trees available for absorbing extra amounts of CO2
- Carbon cycle is disturbed, affecting climate patterns
3. Agriculture:
- Atmospheric methane increased over 130% since 1750
-
Rice growing & cattle rearing produce all 3 greenhouse gases:
o CO2; burning organic waste & cattle breathing
o Methane; digestive process of cattle & paddy growing
o Nitrous Oxide; nitrogen fertilizers
- Agricultural activities increased due to rapid population growth
4. Garbage Treatment:
- Garbage decomposition in landfills releases methane
- Incineration emits CO2 & nitrous oxide
5. Industrial Activities:
-
Manufacturing produces man-made greenhouse gases
CFCs are chemical components (greenhouse gases) which damage
the ozone layer
- HFCs replaced CFCs in the 1980s to produce foams & solvents
- Aluminum smelting & magnesium production release PFCs &
SF6s (man-made greenhouse gases)
- Nylon production releases nitrous oxide
(III) Non-human factors
1. Change in Earth's Orbit's Shape:
- The earth's orbit is generally elliptical
-
A 100,000-year-cycle changes the earth's orbit from nearly circular
to elliptical & back again
Solar radiation varies the most when the orbit is most elliptical
2. Change in Earth's Axis's Tilt:
- The obliquity of the Earth's axis ranges from 22.8˚ - 24.4˚ over a
41,000-year-cycle
- High obliquity allows stronger summer & weaker winter suns;
larger seasonal temperature differences (especially at high altitudes)
- Low obliquity causes polar regions to receive less solar radiation
3. Amount of Aerosols in the Atmosphere:
-
Aerosols are tiny particles suspended in the air
Induced naturally & by human activity
Most are involved with reflecting radiation back to space
Volcanoes induce aerosols
7.4: Global Warming Effects
(I) Global warming consequences
1. Rising Sea Levels:
- Snow & ice covers melt notably in the Arctic & Antarctica,
causing meltwater to run into the oceans
- Thermal expansion of seawater when the earth gets warmer
- Global average sea levels risen 1.8mm/yr between 1961-2003
- Predicted rise by 1m by 2100
2. Climate Change:
A. Precipitation Patterns:
o Melting of ice caps releases more water into water cycle
o Higher evaporation rates due to higher temperatures
o Globally more precipitation, with some experiencing less
o Warming of oceans increases water vapour in atmosphere
o Water vapour in atmosphere has been increasing since 1900s
B. Climatic Regions:
o Tropical areas extend polewards for hundreds of km
o Originally temperate climates become hotter
o Global average temperature increases 2˚C --> temperate areas
shift polewards as much as 300km
C. More Frequent Extreme Climate Events:
o Tropical cyclone formation is closely linked to tropical
ocean temperatures
o Warmer ocean temperatures --> tropical cyclones intensify
o Warm air --> higher evaporation rate & intensity --> more
frequent intense rainfall & snowfall & therefore flooding
o Changes in air temperatures -->Pressure & wind patterns
affect moisture brought by wind --> affects precipitation
patterns --> drought
o Warmer world --> Instability in atmospheric processes -->
increased unpredictability of climate
3. World Ecosystem Changes:
A. Desertification:
o Rise in evaporation rate reduces soil moisture
o More soil erosion threatens arid & semi-arid areas
o Pace of desertification increases
B. Extinction of Species:
o Climate change --> affects habitats
o Habitats that do not adapt will die out
o Extinction / rapid growth of species disturbs food chain
C. Coral Bleaching:
o Warmer water is unfavourable for coral growth
o Warm water kills algae --> coral loses colour --> corals die
(II) Its effect on humans
1. Health Risks:
- Distribution pattern of carriers of infectious diseases is altered
- Tropical diseases travel to more temperate areas
- Hotter summers --> more heat-related health problems & more
heat waves --> more deaths
2. Coastal Flooding:
- Rising sea levels erode coasts --> more storm surges & flooding
-
1m rise in sea level brings disaster to billions in coastal & low-lying
countries (e.g. Maldives)
3. Agriculture & Food Supply:
- Higher evaporation rates --> loss of soil moisture --> decrease in
land's productivity
- Rising sea levels flood coastal lowlands & deltas
- Warmer & shorter winters --> more active pests
- Risk of droughts & floods lower crop yield
4. Recreation & Tourism:
- Glaciers on high mountains will melt --> affects ski resorts
- Mild Mediterranean climate becomes too hot for tourists
- High-latitude regions get temperate climate --> more popular
5. Freshwater Supply:
- Higher evaporation rates --> accelerated water loss of lakes & rivers
- Decrease in precipitation --> freshwater supply shortage
- Glaciers & ice caps serve 16.6% of global population
(III) Different stakeholders on global warming
- Winters in cold areas lose severity --> cold-related deaths decrease
- Rainfall in some areas increase --> ease water shortages & create
better economic development environment
- Melting of Arctic ice --> short shipping routes & easy oil drilling
- Longer growing seasons & frost-free periods --> crop yields of
temperate areas increase + New plants can grow near polar areas
- LEDCs rely on agriculture, have less resources --> major losers
7.5: Global Warming Solutions
(I) Global warming solution methods
1. Replace Fossil Fuels with Renewable Energy:
Energy Type
Description
Benefits
Solar
Solar panels to Clean & safe
collect sunlight
Costly & relies on
climatic setting
Wind
Windmills moved Clean & cheap
by wind drive the
turbines
Interferes
with
reception, poses
danger to birds &
"visual pollution"
Geothermal
Extracted
from N/A
heat inside earth
Higher cost than
natural gas
Tidal & Wave
Energy
from N/A
masses of moving
water
Costly
Biofuel
Refined
from CO2
released
corn, sugar cane from
burning
& soybeans
biofuel captured
by the plants they
Farmlands
produce fuel crop
instead of food
crop; biodiversity
are made from
Drawbacks
decreases
2. Reduce Greenhouse Gas Emissions:
A. Improving Energy Efficiency:
o Over 60% of energy is lost while burning fossil fuels
o CO2 is reduced when efficiency is improved
B. Improving Transportation:
o Most transport is powered by fossil fuels
o Transport generates 25% of global greenhouse gas emissions
o Magnetically levitated trains use 10% of energy used in
regular trains
o Mass transit systems & encouraging public transport
reduces private car use --> lower carbon emission
o Hydrogen powered cars are eco-friendly
C. Recycling:
o Reduce greenhouse gases from landfills & incinerators
o Manufacturing recycled materials saves energy
o Less energy used --> less CO2 emissions
D. Raising Public Awareness via Education:
o Educate disastrous effects of Global Warming
o Provide better living environment for future generations
2. Engage in Large-Scale Afforestation:
- Trees absorb CO2 during photosynthesis
- Global Warming is eased in the long run
- China has carried out afforestation with promising results
3. Sustainable Development:
- Farm sustainably; reduce nitrogen fertilizers
- Population control policies reduce fossil fuel demand
- Develop green technology; use renewable energies economically
- Develop cities that keep greenhouse gas emissions low
(II) The international community
1. Kyoto Protocol:
-
Signed in 1997, ratified in 2002 & enforced in 2005 as an agreement
to reduce emissions:
- Committed MDCs reduce collective emissions by 5% from 1990
levels before 2012
- LDCs exempted from tight emission controls set
- "Trading system" for countries that help LDCs cut emissions
2. Obstacles in International Cooperation:
-
-
Some MDCs did not follow their commitment (e.g. US, Aus, UK)
US was reluctant to sign & help combat Global Warming:
o LDCs not required to take responsibility
o LDCs' rate of greenhouse gas emissions increased a lot
o Reducing emissions incurred extra costs; living standards &
economic growth of MDCs were affected
LDCs argue MDCs should bear more responsibility:
o Build-up of greenhouse gases mainly caused by MDCs;
LDCs in early stages of industrialisation feel "penalised"
o MDCs exploit rights of LDCs to further develop the economy;
LDCs find it unfair to be forced to reduce emissions
o Some LDCs have higher emission levels but lower per-capita
emissions levels when compared to MDCs
o MDCs have more technology & capital to combat the problem
- International cooperation is hindered mainly by costs incurred
3. The Bali Convention:
- Held after IPPC published the Fourth Assessment Report in 2007
-
Representatives from over 180 countries attended
-
The agreement:
o Long-term cooperative action is necessary
o Both MDCs & LDCs are responsible to combat global warming
o Deep cuts in greenhouse gas emissions
Due to differences in capability, levels of responsibility between
MDCs & LDCs will vary
"Bali Roadmap" adopted in 2009 to replace Kyoto Protocol targets
-