#2 - Global Climate: Vulnerability & Resilience

Define climate change

A long term shift in global weather patterns & temperatures

Give example of greenhouse gases

Carbon dioxide, methane, water vapour, nitrous oxide

How do greenhouse gases work? (3)

1. Layer in atmosphere allows sunlight (short wave) to pass through & warm Earth’s surface

2. Earth radiates heat as long wave infrared upward towards space

3. GHGs absorb this radiation & re-emits it in all directions, delaying escape into space

What external factors could be causing climate change?

1) Changes in the Sun’s activity

2) Earth's distance from the Sun decreasing

Define positive feedback

Knock on effects in natural systems which accelerate changes that have already started to occur

Define negative feedback

When a system adjusts itself in a way that lessens or cancels out the effects of the original change, restoring equilibrium

What happens to carbon in oceans during climate change?

1. Global temperatures rise which warms the oceans

2. Oceans are less able to store dissolved gas

3. CO₂ stored in oceans is released to the atmosphere

4. More CO₂ = more climate change

Describe an example of negative feedback with plants (5)

1. Increased use of fossil fuels = more CO₂ emitted

2. More CO₂ = more global warming & CC

3. More insolation = plants grow more

4. More plants = more CO₂ is absorbed

5. Less CO₂ = temperatures decrease, slowing CC

What is global dimming?

The gradual decrease in ‌the amount of sunlight reaching the Earth's surface due to an increase in atmospheric pollutants

What are reasons for variation in solar radiation? (3)

1) Volcanic emission - releases sulphur dioxide into stratosphere forming aerosols that reflect insolation into space

2) Changes in Earth's orbit around sun

3) Cosmic collisions - injects stratospheric dust & aerosol that scatter & absorb sunlight

What are the Milankovitch cycles?

Long-term periodic changes in Earth’s orbit & rotation, affecting solar radiation received & bringing climate change

What is a sunspot?

Dark areas on the sun where intense magnetic storms are happening, causing an increase in solar output

Define albedo

How much solar radiation a surface reflects

Compare the albedo of different surfaces (2)

• White surfaces = higher albedo, reflecting more solar radiation

• Black surfaces = lower albedo, absorbing more solar radiation & retaining heat

Describe negative feedback with sea ice (6)

1. Sea ice melts & darker ocean begins to absorb sunlight

2. Increased evaporation & condensation forming clouds

3. Clouds reflect sunlight, so ocean temp decreases

4. Sea ice reforms

5. Albedo increases

6. More solar radiation reflected etc

Describe positive feedback with permafrost thawing (3)

1. As temperatures rose several degrees, permafrost ring around the Arctic Ocean has already begun to thaw

2. This melting releases vast amounts of carbon dioxide & methane

3. These gases build up a layer in atmosphere, trapping & reflecting sunlight → more global warming

What evidence do we have for climate change?

Ice cores, fossils, ice cover, glacial retreats

How can we draw conclusions from ice cores?

Ice cores with high number of oxygen 18 isotopes mean the ice was formed when the temperature was cooler

What human activities drive global warming? (3)

1) Combustion of fossil fuels → releases CO₂

2) Deforestation → less trees to absorb CO₂ = build up layer in atmosphere

3) Traffic pollution → releases carbon monoxide, nitrogen dioxide, fine particulate matter

What is a biome?

Large plant and animal communities covering vast areas

What are causes for sea level rise?

1) Thermal expansion of water

2) Ice caps melting

What kinds of extreme weather can occur?

Floods, cyclones, droughts and landslides

Why are there likely to be more floods?

More solar radiation → more water evaporation & condensation → intense hydrological cycle → more rainfall → flood

Why is there likely to be more cyclones?

Cyclones draw strength from heat in the oceans

Why is there likely to be more droughts?

Increased solar radiation → more heatwaves → surface water evaporated

How does climate change affect biomes?

It means that as temperatures get warmer, the biomes will migrate either north, south or to higher altitudes to avoid the heat

How to work out risk?

Hazard x vulnerability / capacity to cope

Define carbon footprint per capita

The amount of carbon dioxide emissions an average person in a country is responsible for

What is the cryosphere

The portions of the Earth's surface where water is in solid form

What is anthropogenic carbon flow

The current amount of carbon emission released annually by a country

Anthropogenic carbon stock

The total size of the store of anthropogenic carbon emissions released since 1750

How has the EU pledged to reduce carbon emissions?

Pledged to cut emissions by 20% by 2020 (compared to 1990)

Describe cap and trade

An environmental policy that sets a cap on total greenhouse gas emissions & issues a limited number of emission allowances to emitters

• Emitters must hold enough to cover their emissions

• Don't have enough credits = cut their emissions, or incur fines which will increase production costs of their products

• Can sell unused allowances to one another → incentivises cleaner energy sources

Why would companies want to limit their carbon emissions?

So they can sell unused carbon allowances for extra profit

What is the EUETS (EU emissions trading system), and why is ineffective?

• World’s largest CET (carbon emissions trading) scheme

• Has been criticised for giving out too many credits → hard to deter emitting activities

Define carbon offsetting

Compensating for one’s emissions by doing something that takes carbon emissions out of the atmosphere elsewhere

• Example: Airlines calculate carbon footprint of passengers & can offset it by paying a fee which funds eco-friendly projects (e.g. planting trees)

Why is most water vapour found in the first 15km of the atmosphere?

Because any higher up and the air has too low pressure to hold the water vapour

What kind of radiation does the atmosphere absorb & emit?

• Absorbs short wave

• Emits long wave

Define insolation

Incoming solar radiation

Greenhouse effect

Natural situation in which heat is retained in Earth's atmosphere by greenhouse gases

Most common greenhouse gas

Water vapour

How do CFCs increase the greenhouse effect?

They destroy ozone and absorb long wave radiation from the Earth

Planetary albedo

Reflection from the Earth's surface (about 7%)

How does pollution lead to global dimming?

1. The polluted air has more soot, ash & sulphur dioxide particles generated by volcanic eruptions & human activities

2. Water vapour will bind to these to create many small water droplets in clouds → increasing its albedo

3. Therefore, more solar radiation is reflected by the cloud

Describe the effects of global warming (5)

1) Melting ice caps + rising sea levels → ⬆ flooding so rapid hydrological cycle | impacts coastline populations, loss of freshwater supply

2) ⬆ Extreme weather events (e.g. drought, cyclone, landslide)

3) Agricultural patterns will change - vigorous hydrological cycle = soil erosion makes land less fertile, reducing crop yields

4) ⬆ Heat/water-related disease (e.g. malaria)

5) Change in biome distribution - species migrate towards poles

Low lying areas that could flood

Maldives, Bangladesh and Netherlands

What is happening to sea ice?

It is decreasing and in 2016 it was at its lowest recorded

Describe positive feedback with sea ice (4)

1. Temperatures increase

2. Sea ice melts

3. Lack of sea ice means bigger waves can form

4. These big waves break up the ice further → lower albedo

List examples of mitigation strategies for climate change (6)

1) Carbon taxes

2) Carbon trading

3) Carbon offset schemes

4) Geo engineering

5) Ocean fertilisation

6) Carbon capture and sequestration

What is carbon trading?

• Permits to emit CO₂ are given out, and one can only emit what their permits allow

• Permits can be traded or bought from other companies

What is ocean fertilisation?

Fertilising the oceans with iron nitrogen and phosphorus:

• Increases the number of nutrients available to organisms

• Trigger an algal bloom that can trap carbon dioxide

What is geo engineering? Give an example

Large scale engineering schemes that increase global dimming (e.g. placing huge mirrors in space to deflect the incoming rays)

What are carbon taxes?

A tax on fossil fuels, encouraging people to use alternatives

What is carbon capture and sequestration?

A method of capturing CO₂ from the atmosphere & storing it underground:

1) It separates CO₂ from other gases emitted from industrial processes

2) It is transported to oil & gas fields, where rocks beneath Earth’s surface retain the CO₂

What was the Kyoto Protocol?

In 1997, countries signed an agreement which stated they would try to cut greenhouse gas emissions by 5% by 2012

What was the Paris Climate Agreement?

In 2015, countries signed an agreement to limit temperature increase to 2°C compared to pre industrial levels

What three factors affect human vulnerability?

- Degree to which people are exposed to climate change

- Degree to which they could be harmed

- Degree to which they could mitigate the potential harm

What are problems that low lying areas face? (5)

1) Increased coastal erosion → risk of flooding

2) Saltwater intrusion into groundwater → contaminates freshwater aquifers = ❌ drinking, irrigation

3) Damage to coral reefs → ecosystem threatened, biodiversity loss

4) Out migration of people

5) A decline in economic activities (e.g. tourism, fishing)

Describe examples of global geopolitical efforts (5)

1988 - The IPCC (Intergovernmental Panel on Climate Change) was set up, provided policymakers w/ scientific assessments on CC’s risks & mitigation strategies

1992 - Rio Earth Summit, 190 countries signed a treaty agreeing to stabilise atmospheric GG concentrations to prevent dangerous interference w/ climate system

1997 - Kyoto Protocol: In Kyoto, 183 countries signed an agreement that they will try cutting greenhouse gas emissions by 5% by 2012

2015 - COP 21 (UN 2021 Climate Change Conference): 195 countries signed a treaty to limit warming by 2°C, each country set their own targets

How do volcanic eruptions cause temporary changes in global climate? (5)

1. Volcanic eruptions eject aerosols into the troposphere & stratosphere

2. These particles will have temporary effects on climate (e.g. formation of dust veils absorbing & back-scattering insolation)

3. Volcanic particulates also deplete ozone in the lower layers of the stratosphere → forms ozone holes

4. The changes are temporary as volcanic particulates are deposited back on the land/ocean

5. Volcanic dust settling on ice → reduce ice’s albedo + increase rate of melting

Non-governmental stakeholder’s action towards climate change - Ben & Jerry’s

• Ben & Jerry’s is a US ice cream company

Actions:

1) Established climate targets (by 2025) approved by the Science Based Target Initiative (SBTI):

• 100% renewable energy → no more coal

• 40% GHG intensity reduction

2) Partners w/ farmers in Europe + US on Caring Dairy programme to promote regenerative agriculture

• Cover cropping, reduced tillage, low synthetic input → increase soil carbon sequestration & enhance soil quality

Case studies - Describe two LICs’ vulnerability to climate impacts

Kiribati -

ECONOMIC: Storm surges damage infrastructure, homes → losses & repair costs strain gov. budget 

• Tarawa alone face coastal-related losses of USD 8-16 million

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Burundi -

ENVIRONMENTAL: Floods lead to soil degradation → threatens ecological health

• Between 2001-2023, ⬇ 6.6% of vegetation so local species (e.g. Eastern chimpanzees) lose food source  

Case studies - Describe two HICs’ vulnerability to climate impacts (6)

Norway -

SOCIAL: Precipitation up by 18% since 1900 → ⬆ landslide risk for fjord + valley regions

In 2013, introduced National Landslide Early Warning Service (Varsom) 

• Real-time alerts for landslides, avalanches based on rainfall, snowmelt levels → near-zero annual fatalities from landslides 

Switzerland -

ENVIRONMENTAL: From 2022-2023, 10% glacier loss → ⬆ flooding frequency, sediment deteriorates rivers & lakes

• Spends CHF 300 million on flood protection annually, preserving aquatic ecosystems