Geography SL - Climate Change (Core Unit)

Atmospheric System

Gases that form 4 distinct layers around the Earth

Name the 4 atmospheric layers (from top to bottom)

• Thermosphere

• Mesosphere

• Stratosphere

• Troposphere

Thermosphere (function & temperature)

Protects Earth from sun’s harmful radiation, x-rays and ultraviolet rays
Temp. = 500 to 2000 degrees celcius (hottest layer)

Mesosphere (function & temperature)

Protects earth from comets and meteorites
Temp. = -2.5 to 90 degrees celcius (2nd hottest layer)

Stratosphere (function & temperature)

holds ozone layer and protects from sun’s ultraviolet rays (UV)
Temp. = -51 to -15 degrees celcius (coldest)

Troposphere (function & temperature)

Provides oxygen & keeps Earth at habitable temperature. Allows weather to occur
Temp. = -51 to 17 degrees celcius (decreases as you climb)

Tropopause

Boundary between troposphere and stratosphere

Stratopause

Boundary between stratosphere and mesosphere

Mesopause

Boundary between mesosphere and thermosphere

Atmosphere

Open energy system receiving energy from the sun and earth

Insolation

Incoming solar radiation

Energy flow in the atmosphere

balance between inputs, outputs and transfers of energy. Earth is neither heating up or calling down

Short wave radiation

radiation and wavelengths of less than 4 microns. Enters Earth by reflecting off clouds being absorbed by the atmosphere

Long wave radiation

electromagnetic energy radiated outwards by Earth when the atmosphere warms and heat is emitted, partly radiating into space

How short wave radiation is used

Given out by the sun. The hotter the energy-supplying body, the shorter the wavelength.
Can be absorbed at:
- Surface
- Reflected back from surface
- Reflected to space from cloud & gases
- Reflected to surface as diffused radiation

How long wave radiation is used

Given out by surface to eventually leave the atmosphere. Transferred back to surface if there is a cloud cover or greenhouse gases that trap it

Factors affecting earth-atmosphere energy balance

• Short-wave radiation reaching surface

• Long-wave radiation leaving atmosphere

How the factors affect earth-atmosphere energy balance

• Latitude (solar radiation) & albedo

• Cloud cover (solar & long-wave radiation)

• Atmosphere characteristics → gas, water vapour, dust/sand (solar & long wave radiation)

Latitude

Measures distance North/South of equator

Latitude effects on solar radiation

• Energy distributed unevenly

• Far away from equatorial line = lower energy input

• If long distance, short waves may be reflected or not reach surface. Lost heat-energy

Albedo effect

ability of surfaces to reflect sunlight. Depends of colour of surface (rainforest/desert) & characteristics (thin/thick clouds)

Clouds

reduces solar (short wave) radiation reaching the surface & long wave leaving the atmosphere

Clouds + Albedo

• Clear sky albedo → albedo without clouds

• Total albedo → albedo with clouds

• Cloud cover impact on albedo

  • the lighter the colour, the more solar radiation reflected to space

Atmosphere characteristics

Gases → can reflect and absorb solar radiation. Also reflects long-wave radiation (Greenhouse effect)

Water vapour → absorbs & reflects solar radiation. Is the cause of 36-66% of the greenhouse effect

Dust/sand → particles in suspension lead to reflection and scattering of solar radiation

Greenhouse gases

gases that trap heat in the atmosphere. It is re-emitted as heat energy into space
e.g. water vapour, carbon dioxide, methane, ozone, etc.

Anthropogenic gases

Greenhouse gases that are human induced

Greenhouse effect

a natural process that warms the Earth’s surface

Greenhouse effect process

When the sun’s energy reaches the atmosphere, some is reflected back to space. The rest is absorbed & re-radiated by greenhouse gases. This keeps Earth 33 degrees warmer than it would be otherwise.

Cause of climate change

increase in greenhouse gases

Carbon dioxide

increasing due to fossil fuels being burned for energy. Human induced CO2 has risen by 50% since the 18th century. Human emissions could reach 75 billion tons per year by end of century. China emits the most. Without CO2, the greenhouse effect would be too weak to keep global average temperature above freezing

Methane

increasing due to agriculture, fossil fuels and landfill waste. Concentration doubled over the past 200 years. Projected 9 million tonnes per year by 2030. China emits the most. Responsible for +25% of global warming. Traps more heat in atmosphere than CO2

CFC’s

increasing due to aerosols and waste (air conditioners & fridges). CFCs were banned a decade ago but production has been increasing. China emits the most. CFCs enhance atmospheric greenhouse effects

Nitrous oxide

increase due to agriculture, fuel combustion, wastewater management & industrial processes. Reached new high of 334 ppb in 2021. China emits the most. Contributes to greenhouse effect due to positive radiative forcing effect

Natural factors of climate change

• Variations in solar energy (sunspots release increased solar radiation)

• Volcanic eruptions → short-term (1-3 years) cooling effect

• Variation in Earth’s orbit (distance from sun changing)

• Clouds/water vapour → absorbs/reflects solar (short wave) radiation

Human factors of climate change

• Burning fossil fuels (coal, gas, oil)

• Deforestation (effects carbon dioxide)

• Increased cattle ranching (methane)

• Fertilisers in agricultural systems (higher nitrous oxide (N2O) concentrations)

Milankovitch Cycle

periodic changes in the orbital characteristics of a planet that control how much sunlight it receives

Eccentricity

changes in orbit shape. Earth’s rotation is not perfectly circular (more elliptical). When more elliptical, more solar radiation enters the atmosphere. Cycle = 100,000 years

Obliquity

most important, the earth’s tilt. Varies between 22.1 to 24.5 degrees. The more tilt, the more extreme seasons. Is the main reason for seasons. Cycle = 41,000 years

Precession

Axial precession. As earth rotates, it wobbles slightly upon its rotational axis. Due to tidal forces caused by gravitational influences of the sun & moon. Cycle = 23,000 years

Long-term changes in energy balance

Ice age → expansion of ice sheets and alpine glaciers due to long period of reductions in Earth’s surface & atmosphere temperature. 110,000 - 10,000 years ago

Jurassic period → atmosphere was warmer and thicker than today. Carbon dioxide levels were likely 4x higher. 119.6 - 145.5 million years ago

Short-term changes in energy balance

Volcanic eruptions → ash & sulfric acid prevent sunlight from reaching surface. Creates cooling affect

Short-term carbon cycle → Plants “fix” carbon out of atmosphere through photosynthesis

Sunspots

Short-term variation in solar energy. Huge magnetic storms on sun’s surface which increases solar radiation to earth

Negative feedback

system that returns to the original “balanced” situation through a self-regulating method of control. Same state of equilibrium.
e.g. global cooling, ice growth, increased albedo, less insolation absorbed

Positive feedback

System that takes a new “balanced” situation through permanent changes in the state of the system. New state of equilibrium
e.g.

Carbon cycle

series of processes by which carbon compounds are interconverted in the environment, involving incorporation of CO2 into living tissue by photosynthesis and its return to atmosphere through respiration, the decay of dead organisms and burning fossil fuels

MEDC Economy & emissions

Portugal:
emissions per capita = 4.05 metric tons
GDP per capita = $26,878.87
Trade balance of goods = -$32.31 billion

LEDC Economy & emissions

Kenya:
emissions per capita = 0.46 metric tons
GDP per capita = $2,187.65
Trade balance of goods = -$14.03 billion

Implications of climate change

• rising sea levels

• increasing storm activity

• agricultural patterns will change

• less rainfall

• up to 40% of species will go extinct

Atmosphere

thin layers of gases surrounding earth. protects from UV radiation, monitor temperatures & provides animals with CO2 and oxygen. Climate change worsens air quality within the atmosphere

Hydrosphere

all water covering earth; liquid & solid. 71% of earth is covered in water. Climate change melts glaciers and ice sheets

Biosphere

all life on earth; humans, plants and animals. Climate change causes some habitats to be too warm or dry for animals to survive

Atmosphere/hydrosphere case study

Shishpar glacier in North Pakistan was thawing due to a record heat-wave which flowed into a nearby lake. Water levels grew too high and triggered a flood that destroyed a nearby village

Changes to atmosphere

• increased greenhouse gases = warmer air

• More atmospheric energy = increased storm activity

• Change in temperature, wind, pressure, precipitation & humidity

Changes to hydrosphere

• rising sea levels could displace 200 million people

• Floods from glacial melt threaten 4 million sq/km (5% of population home)

• Changes in sea ice

• Acidification → changes in carbon stored in ice & oceans

Changes to biosphere

• vegetation could increase or decrease

• Thawing of permafrost

• Changes in biomes (too fast = migration/extinction)reduction in biodiversity

Consequences of climate change

• 75-250 million projected to be exposed to increase in water stress by 2020

• Agricultural production projected to be compromised by climate variability and change. Affects food security exacerbate malnutrition

• Some African countries, yields from rain-fed agriculture reduced by 50% by 2020

Consequences of climate change case study: Asia

Freshwater availability across Asia projected to decrease. Could affect +1 billion people by the 2050s. Coastal areas, especially heavily populated mega-delta regions will be at greatest risk due to regions rapid urbanisation, industrialisation and economic development

Consequences of climate change case study: America and hurricanes

Caused by thunderstorms (use ocean heat as fuel) and warming oceans (storms pull in more water vapour & heat) which makes stronger winds, rainfall and flooding. Some hurricanes cause up to $1 billion in damage and displacement due to damage of housing. Hurricanes spread bacteria which leads to mini outbreaks of diseases

Risk

both the possibility of danger and simultaneously its potential consequences

Vulnerability

conditions determined by physical, social, economic and environmental factors which increase susceptibility to the impacts of hazards

Adaptation

anticipating adverse effects of climate change and taking appropriate action to prevent or minimize the damage

e.g. America invest in robust coastal defence infrastructure to minimize damage caused by hurricanes

Mitigation

reducing climate change by reducing sources of the problem

e.g. America build energy-efficient, green building techniques to reduce emissions from electricity generation

Exposure

the degree to which people are exposed to climate change

Sensitivity

the degree to which they could be harmed by exposure to climate change

Disparities in exposure case study

Netherlands = MEDC, HIC. Located in Europe. One of the most flood-prone countries in the world. exposed = land captured by the sea. vulnerable = lives &homes at risk from flooding. Dutch adapt by reinforcing dikes and dunes. Dutch want to reduce greenhouse emissions by 49% by 2030

Bangladesh = LEDC, LIC. Located in Asia. one of the most flood-prone countries in the world. exposed = losing land due to rising sea levels. vulnerable = flat topography causes more extreme flooding, destroying infrastructure. government has implemented 726km of river-bank protection. Wants to increase tree cover from 22% to 25% by 2030

COPs

conference of the parties. Members make plans for their countries on how to reduce emissions and impacts of climate change. They meet every year to review each country’s progress. formed 1995

Paris Climate agreement

• Keep warming below 2 degrees celcius

• Rich countries must invest $100 billion from 2020

• Developing countries encourages to “enhance efforts”

• Developed countries must provide financial support

• Review progress every 5 years

Mitigation strategies

• reducing energy consumption

• reducing emissions of Nitrous Oxide and methane from agriculture

• geo-engineering

• using alternatives to fossil fuels

• using biomass as a fuel source

Carbon sinks

anything that absorbs more carbon from the atmosphere than it releases
e.g. trees

geo-engineering

deliberate large-scale intervention of earth’s natural system to counteract climate change
e.g. sunshades in earth’s orbit that reflects sunlight back into space

pollution management/control

• stopping forest clearance

• improving public transport

• setting national limits on carbon emissions

Carbon taxes

taxes levied on the carbon emissions required to produce goods and services

Carbon trading

use of a marketplace to buy and sell credits that allow companies to emit a certain amount of CO2 per year

Carbon offset schemes

reduction/removal of emissions to compensate for emissions released elsewhere

Civil society

aggregate of NGOs and institutions that manifest interests and will of citizens

TNC climate change action

McDonalds → committed to reducing greenhouse gas emissions caused by its restaurants and offices by 36% by 2030

Civil society climate change action

Save the Children → committed to reducing their own greenhouse gas emissions and environmental impacts