earth's spheres and climate change ༄˖°.🍂.ೃ࿔*:･

Atmosphere

The gas layer surrounding Earth (78% nitrogen, 21% oxygen, 1% trace gases) that protects life and regulates temperatures.

Lithosphere (Geosphere)

The solid, rocky outer layer of Earth consisting of the crust and rigid upper mantle.

Hydrosphere

All water on Earth (approx. 97% oceans, 2% glaciers/ice caps, 1% other sources).

Biosphere

All living organisms and their habitats where the atmosphere, lithosphere, and hydrosphere interact.

Matter and Energy Transfer

Earth's spheres interact through the continuous exchange of matter and energy.

Matter transfer and energy transfer

1. The movement of physical substances between spheres.

Example: Water evaporates from the hydrosphere into the atmosphere.

2. The movement of heat or radiation between spheres.

Example: Solar energy heats the land (lithosphere), which transfers heat to the air above it (atmosphere) through conduction.

Key rule:

Matter cycles through Earth's spheres.

Energy flows through Earth's spheres.

Carbon sink

A reservoir that absorbs more carbon than it releases.

Examples: Oceans and rainforests.

Carbon source

A reservoir or process that releases more carbon than it absorbs.

Examples: Burning fossil fuels and volcanic vents.

Flux

The movement or change of a substance.

Carbon Flux

The rate and direction of carbon moving between reservoirs.

- Uptake (removal):

Carbon moves from the atmosphere into the biosphere or hydrosphere.

Example: Plants absorb CO₂ through photosynthesis.

- Release (addition):

Carbon moves from the biosphere, lithosphere or hydrosphere into the atmosphere.

Example: Burning fossil fuels releases CO₂.

Dynamic equilibrium:

When carbon uptake and release are balanced, the system remains in dynamic equilibrium. If uptake and release become unbalanced, atmospheric CO₂ levels can change, contributing to climate change.

Fossil Fuel Combustion Impact

Transfers stored carbon from the lithosphere to the atmosphere rapidly, disrupting the carbon cycle.

Deforestation Impact on Carbon

Deforestation has a double impact:

1. Loss of carbon sink: Fewer trees means less CO₂ is absorbed through photosynthesis.

2. Creation of carbon source: Burning or decomposition of cleared trees releases stored carbon into the atmosphere.

Greenhouse Gases (GHGs)

A gas that absorbs infrared radiation, causing its molecules to vibrate and re-radiate heat energy, which traps warmth in the atmosphere.

Natural vs. Enhanced Greenhouse Effect

The natural effect keeps Earth habitable (~15°C); the enhanced effect is human-driven intensification causing global warming.

Oceans as Carbon Sinks

Oceans cover ~71% of Earth and absorb over 30% of human CO₂ emissions, slowing atmospheric warming.

Ocean Acidification Process

Atmospheric CO₂ dissolves in seawater, forming carbonic acid which releases hydrogen ions and lowers pH.

Impacts of Ocean Acidification

Reduces carbonate ions, leading to coral reef degradation, weaker calcium carbonate shells, and disrupted marine food webs.

Urbanisation what is it? What are the effects?

The growth of cities often involves clearing land and increasing energy use.

Reduces vegetation that absorbs CO₂.

Increases emissions through transport, buildings and energy use.

The Enhanced Greenhouse Effect

The human-driven intensification of heat trapping in Earth's atmosphere.

1. How it happens:

- Humans burn fossil fuels and clear forests.

- More CO₂ and other greenhouse gases enter the atmosphere, while fewer trees absorb CO₂.

- Higher greenhouse gas concentrations mean more outgoing infrared radiation is absorbed and re-emitted.

- Less heat escapes directly into space.

Earth's average temperature rises.

How the enhanced greenhouse effect links to the carbon cycle

The combustion of fossil fuels transfers carbon from the lithosphere to the atmosphere, increasing atmospheric CO₂ concentrations. Deforestation also reduces carbon uptake by the biosphere. These changes disrupt the balance between carbon uptake and release, strengthening the greenhouse effect and contributing to global warming.

Global warming

A gradual increase in Earth's average temperature, mainly caused by the enhanced greenhouse effect.

Climate change

Long-term changes in climate caused by natural processes and human activities. It includes global warming and other changes to weather patterns, rainfall and extreme events.

Remember: Global warming is one part of climate change.

Earth's vital signs

- Surface temperature: Increased by about 1.1°C since 1880.

- Ocean heat content: At record historical highs.

- Arctic sea ice: Declining at approximately 12.2% per decade for the relevant September minimum measurement.

- Global sea level: Rose by more than 20 cm over roughly the last century.

Atmospheric dissolution:

CO₂ moves from the atmosphere into the hydrosphere by dissolving in surface seawater.

- CO₂ continually dissolves into and escapes from ocean surface water.

- Higher atmospheric CO₂ concentrations generally increase the rate at which CO₂ dissolves into the ocean.

- Dissolved CO₂ reacts with water, leading to chemical changes.

Ocean Acidification 

Ocean acidification occurs when carbon dioxide from human activities enters the atmosphere and is absorbed by the ocean, lowering its pH.

• Higher atmospheric CO₂ dissolves into seawater, forming carbonic acid that lowers pH and depletes carbonate ions needed for shell building.

Land ice vs Sea ice

Sea ice 

• Already in the ocean

• Melting → no sea level rise

Land ice 

• Stored on land (glaciers, ice sheets)

• Melting → adds water to oceans

• Sea levels rise