#2 - Global Climate: Vulnerability & Resilience

Climate change

A long term shift in global weather patterns & temperatures

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

How cold would the earth be without GHGs?

-18*C

What external factors could be causing climate change?

1) Changes in the Sun’s activity

2) Earth's distance from the Sun decreasing

Positive feedback

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

Negative feedback

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

Example of positive feedback

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 means more global warming

Example of negative feedback (5)

1. Increased use of fossil fuels = more CO₂ emitted

2. More CO₂ = more global warming

3. More warmth = plants grow more

4. More plants = more CO₂ is absorbed

5. Less CO₂ = temperatures decrease

What is global dimming?

The reflection of sunlight due to tiny solid particles and particulates in the air

Reasons for variation in solar radiation (4)

1) Volcanic emission

2) Changes in solar radiation

3) Changes in earth's orbit

4) Cosmic collisions

What are the Milankovitch cycles?

The Earth's axis wobbles, changing over 22,000 years bringing climate change

What is a sunspot?

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

Albedo

How much solar radiation a surface reflects

What kind of surface has the highest albedo?

• White surfaces = higher albedo, reflecting more solar radiation

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

Example of negative feedback with ice

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

2. Increased evaporation

3. More clouds

4. Clouds reflect sunlight, so ocean temp decreases

5. Sea ice reforms

6. Albedo increases

7. More solar radiation reflected etc

Describe the issue of permafrost thawing

• The vast permafrost ring around the Arctic Ocean has already begun to thaw in places where temperatures have risen by several degrees

• This melting is releasing vast amounts of carbon dioxide & methane, potentially affecting the global climate further (positive feedback loops)

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

How can humans cause global warming?

- Fossil fuels

- Deforestation

- CFCs

- Atomic bomb testing

- Traffic pollution

What is a biome?

Large plant and animal communities covering vast areas

Causes for sea level rise

- Thermal expansion of water

- Ice caps melting

How much has sea levels risen since 1900?

200mm

What kinds of extreme weather can occur?

Floods, cyclones, droughts and landslides

Why are there likely to be more floods?

More water is being evaporated so more rain will fall and cause a 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?

There will be more heatwaves and water evaporated

Example of a biome

Rainforest

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

Health hazards

Malaria may move to other places as the mosquitoes move, food insecurity

How might climate change affect population?

It can cause people to migrate, putting pressure on other countries

Per capita carbon footprint

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

Cryosphere

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

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

Why is the EUETS (EU emissions trading system) not effective?

World’s largest CET (carbon emissions trading) scheme has been criticised for giving out too many credits

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 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

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

Human activities that increase CO2 levels

Respiration, combustion and deforestation

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 and sulphur dioxide particles for the water to bind to.

2. This creates many small water droplets, more so than in normal clouds

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

Effects of global warming

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

2) Increased frequency of extreme weather events (e.g. drought, cyclones, landslides)

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

4) Increased disease (e.g. malaria)

5) Change in in biome distribution - species migrate towards poles

Low lying areas that could flood

Maldives, Bangladesh and Netherlands

How much is it predicted that sea levels will rise by 2100?

Between 40cm and 80cm

What is happening to sea ice?

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

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

Examples of mitigation strategies (6)

1) Carbon taxes

2) Carbon trading

3) Carbon offset schemes

4) Geo engineering

5) Ocean fertilisation

6) Carbon capture and sequestration

Carbon trading

Permits to emit CO2 are given out, and you can only use what your permits allow you - but permits can be traded or bought from other companies

Ocean fertilisation

Fertilising the oceans with iron nitrogen and phosphorus increases the number of nutrients available to organisms and can trigger an algal bloom that can trap carbon dioxide

Geo engineering

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

Carbon taxes

A tax on fossil fuels that will encourage people to use alternatives

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, 183 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, 174 countries signed an agreement to limit temperature increase to 2°C compared to pre industrial levels

Three factors affecting 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

Problems that low lying areas face

- Increased coastal erosion

- Saltwater intrusion into groundwater

- Damage to coral reefs

- Out migration of people

- A decline in economic activities

Describe global geopolitical efforts (5)

1988 - The IPCC (Intergovernmental Panel on Climate Change) was set up

1992 - Rio Earth Summit, 190 countries signed a treaty agreeing to stabilise atmospheric GGs 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 particulates (aerosols) into the troposphere & stratosphere.

2. These particulates will have several temporary effects on climate (e.g. formation of dust veils absorbing & back-scattering incoming radiation)

3. Volcanic particulates also thought 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 and tend to 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 approved by the Science Based Target Initiative (SBTI):

• 100% renewable energy by 2025 → no more coal

• 40% GHG intensity reduction by 2025

• 80% GHG intensity reduction by 2050

2) Partners w/ farmers in Europe + US on Caring Dairy programme & Low Carbon Dairy pilot project to promote regenerative agriculture

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

Case studies - Compare Kiribati and Norway’s vulnerability to climate impacts

Impact	Kiribati	Norway
Environmental	Sea level rise → erosion degrading beaches + nesting habitats (seabirds & turtles endangered)	Mountainous terrain (w/ fjords) that buffer coasts  <10% population at flood risk
Social	Flooding reduces habitable land & forces internal migration toward South Tarawa → stress on housing + services	Since 2013, National Landslide Early Warning Service (Varsom)  Real-time alerts for landslides, avalanches based on rainfall, snowmelt levels Near-zero annual fatalities from landslides
Economic	Storm surges submerge + damage infrastructure, homes → losses & repair costs strain government budget  Tarawa alone face coastal-related losses of $8-16 million SS potentially causing up to $430 million in capital losses	Climate-related losses often below 1% of GDP Sovereign wealth fund >$1.5 trillion, used to achieve Paris Agreement goals (e.g. no biodiversity loss, companies achieve net-zero GHG emissions)