UNIT 2: CLIMATE CHANGE - KEY CONCEPTS

State the ‘Spheres’ of the Earth

There are four major subsystems

• "lithosphere" (land)

• "hydrosphere" (water)

• "biosphere" (living things)

• "atmosphere (air)

Explain the importance of Atmosphere in agriculture

The atmosphere consists of gases and tiny water particles that are helf in place by Earth’s gravitational force.

Without gravity, gases would escape into space. Therefore, planets with weaker gravity cannot hold onto their atmospheric gases as effectively, resulting in thinner or less dense atmospheres.

Identify the compositon of the atmosphere

Nitrogen, Oxygen, Argon, carbon dioxide, water vapour, and trace gases

Explain Shortwave radiation

Can be known as: Incoming Solar Radiation or ‘insolation’

These are powerful energy emitted by the sun, in the form of visible light and UV light.

Distribution: Unevenly spread. The equator receives more radiation than the poles, due to the relative distance from the sun and the surface area.

This incoming radiation is then absorbed and circulated by the atmosphere and oceans, powering the planet’s weather and climate.

Absorption: Some incoming shortwave radiation is absorbed by atmospheric gases.

Reflection: Some incoming shortwave radiation is reflected by clouds.

Explain Longwave radiation

Relatively weaker energy emitted by the earth, in a form of infrared rays

How does this work: Powerful high-frequency shortwave radiation from the sun is absorbed and then re-emitted from both particles in the atmosphere and the surface of the earth at a lower, less powerful frequency (i.e. longer waves).

Absorption: Clouds in the troposphere absorb and prevent longwave radiation from escaping into space. If no clouds, 80% of emitted longwave radiation is lost to space. This is why clear days and nights in winter are so cold.

Greenhouse Gases: Water vapour, carbon dioxide and ozone absorb long-wave radiation very well, heating the earth. This is why they are known as ‘greenhouse’ gases.

What is the Greenhouse Effect?

A natural process that warms the earth’s surface.

Greenhouse gases absorb and reradiate longwave radiation that was initially shortwave, entering Earth’s atmosphere.

The absorbed energy warms the atmosphere and surface, maintaining the average global temperature at around 33°c

State all the GREENHOUSE GASES (GHGs)

A gas that absorbs and emits longwave radiation

Note: they do not absorb/emit shortwave radiation, it passes through them on their way to the earth’s surface.

GHG by concentration

1. Water vapour

2. Carbon Dioxide

3. Methane

4. Nitrous Oxide

5. Ozone

6. CFCs

What is Global Warming Potential?

A GHG potency in terms of how much heat it can re-radiate varies, as does its concentration in the atmosphere and the period it remains there. This is called ‘Global Warming Potential’

CO2 absorbs less heat than methane but remains in the atmosphere for a lot longer.

Which GHG has the biggest impact in the atmosphere?

Water vapour and carbon dioxide have the largest overall warming effect within the atmosphere.

Methane and nitrogen oxides have a lesser overall warming effect

What is meant by feedback loops?

All systems need to be balanced, to achieve this they need to self-regulate through feedback loops

Explain positive loops and provide 2 examples

A positive feedback loop increases the amount of change with each loop. This leads to an imbalance with the system spiralling out of control. (Less common in nature) = Unstable

Melting ice

As the planet warms, ice melts, revealing darker land or water that absorbs more heat. This causes more ice to melt, which leads to more warming, and so on.

Permafrost melting

As the planet warms, more permafrost melts, releasing methane, a greenhouse gas that traps heat in the atmosphere

Explain negative loops and provide 2 examples

A negative feedback loop decreases the amount of change by reducing some of the inputs with ‘checks’, returning the system to stability. Keeping it in a dynamic equilibrium = Stable

Coastal erosion:

If a storm erodes a large portion of a beach, the newly exposed cliff face can protect the base from further erosion, stabilizing the coastline

Predator-prey dynamics:

When a predator population increases, it puts pressure on the prey population, causing it to decline, which then leads to a decrease in the predator population.

Explain the Albedo Effect

In the context of climate change, it’s a measure of how much shortwave radiation from the sun is reflected back into space.

‘Bright white reflects light”

Lighter = High Reflectivity = High Albedo

Darker = Low Reflectivity = Low Albedo

What does Permafrost contain?

Permafrost contains vast quantities of frozen, undecomposed, organic material (vegetation, bacteria, organisms, etc.) from when these regions were warmer - this is almost 50% of total global organic soil matter.

What is permafrost?

Any ground that remains completely frozen -0*C or colder for two consecutive years

• A combination of soil, rock, and sand are held together by ice

• There doesn’t need to be snow on the ground for the earth below the surface to be frozen.

What is the Solar Cycle?

The solar cycle is the cycle that the Sun’s magnetic field goes through approximately every 11 years.

How does the solar cycle alter climate?

Solar Minimum: The cycle where the sun has least sunspots

Solar Maximum: Middle of the cycle where the sun has the most sunspots

• Variation in solar irradiance:

  During a solar cycle, the Sun's overall brightness fluctuates slightly, with more energy emitted during solar maximum and less during solar minimum. 

• Impact on temperature:

  This variation in solar radiation can cause a small change in Earth's average temperature, usually less than 0.1 degrees Celsius. 

What is global dimming?

When incoming shortwave radiation is reflected back into space, preventing it from reaching the earth’s surface due to visible air pollution, such as soot, ash, sulphur compounds and other pollutants.

What are the issues caused by global dimming?

Changing Cloud Albedo: More shortwave radiation is reflected back into space due to polluted particles ‘seeding’ clouds, making the clouds denser and therefore changing their albedo.

Ocean Currents: Oceans absorb and release heat, driving the global climate system and making earth habitable. These clouds shield the oceans from shortwave radiation thus disrupting weather systems.

Regional Drought: This changing of weather patterns is suspected to have been responsible for many of the world’s droughts over the last 50 years.

Global Dimming Paradox: The big one - due to the dimming effect reducing temperatures we may well be underestimating the effects of manmade climate change.

What does Globlal Warming Potential mean?

Global warming potential is the calculation of the amount and time of gas that remains in the atmosphere.

CO2 is the benchmark gas for comparing GWP as it is the most abundant GHG in the atmosphere

The higher the GWP number, the greater potential warming impact it has.

What does anthropogenic climate change mean?

Anthropogenic means ‘man-made’ climate change

A theory that explains the long term increase in the average temperature of the Earth’s atmosphere as an effect of human industry and agriculture. AKA ‘the enhanced greenhouse effect’.

though industry, agriculture and transportation

What is the Hydrosphere?

The hydrophere is the total amount of water on the planet. This includes liquid, vapor, ice, ice sheets, glaciers, clouds, etc.

What are ‘Continental Glaciers’

This is also known as ‘ice sheets’, these are glacial land ice that extends more than 50,000km2

It is presently found on Greenland and Antarctic - due to these being the coldest regions of Earth

• Contains 70% of all freshwater on Earth

• Sea level rise, it will increase greatly if ice sheet completely melted

• Ice sheets regulate temperatures that affect global climate patterns (due to albedo effect)

What is an ‘‘Ice Cap'“

A mass of glacial land ice that extends less than 50,000km2

Commonly in regions with cold temperatures

Melting ice caps provide essential water for many of the world’s densely populated regions, especially from the Himalayas to India, Bangladesh, China, and SE Asia.

• Energy: Many glacially fed rivers are dammed for hydroelectric power, providing energy for industry.

What is the Cryosphere?

Locations on the planet where liquid water is turned into soil form

It can be found in extreme latitudes like the arctic/antarctic

• Permafrost

• Sea ice

• Snow

• Land cover

• Ice sheets

Cryospheres include glaciers, ice, snow, icebergs, permafrost, mountains, etc.

Define the ‘Carbon Cycle’

The process in which carbon atoms continually move from the atmosphere to the earth and back again. There are two types of carbon cycles: Slow and Fast

Explain the slow carbon cycle

Over years, carbon moves between the atmosphere, lithosphere and oceans. Rocks are weathered and enter the atmosphere, and rivers. This solid matter: rocks (sediment) reaches the ocean floor and absorbed into the earth’s crust, then reentering the atmosphere and lithosphere through volcanic eruptions.

Explain the fast carbon cycle

Absorb atmospheric carbon dioxide through photosynthesis, as it is moved through the good chain and released through respiration. Prior to this, organisms use carbon to build cells, proteins and and DNA molecules. Fast carbon moves 1000 times more carbon per year than slow carbon cycle

What are extreme weather events?

Weather that is significantly different from the usual weather pattern in a given place over a period of day or longer.

Including unexpected, unusual, severe or unseasonal weather.

E.g. heatwaves, cold waves, droughts, temperate cyclones, tropical cyclones /8typhoons, hurricanes & cyclones)

CAUTION: Floods(caused by extreme weather), tsunamis, and earthquakes are not extreme weather, but are natural disasters

What are droughts and its different categories

Metrological drought Occurs when there is a prolonged period of time below average precipitation, it comes before the following

Agricultural drought: initially can be caused below average precipitation, but exacerbated by poorly planned irrigation systems and farming practices.

Hydrological drought: Caused by below average rainfall, followed decreases in quivers, lakes and reservoirs falling below replenish-able levels .

What are economical impacts of droughts?

• Food insecurity

• Energy insecurity

• High food production costs

• Reduction or loss of industrial production

• Loss of tourism revenue

What are environmental impacts of droughts?

• Lower water levels

• Increased concentration of pollutants in water

• Drying out of ecologically essential wetlands

• More intense bushfires

• Loss of biodiversity

What are the social impacts of droughts?

• Direct effect of heat waves

• Reduced access to drinking water

• High food prices in supermarkets

• Stress caused by failed harvests

• Increase inequalities between HIC & LICs

What are biomes?

A community of plants & animals (flora & fauna) that have common characteristics for the climate or landscape that they live in

Different types of flora and fauna in each biome depends on the following:

• Temperature range

• Precipitation levels

• Soil fertility

What are habitats?

A type of natural environment in which a particular species or organism lives. it provides food, shelter, protection and potential reproduction.