Chemistry of the Atmosphere

What was the process of production of gases in early atmosphere?

• 4.6 billion years ago, as the earth formed, volcanoes began to form which released, CO2, nitrogen, ammonia, and water vapour.

• As the earth cooled, water vapour condensed into oceans and seas.

• Earth’s early atmosphere had little to no oxygen, and vast amounts of carbon dioxide.

How did Carbon Dioxide levels decrease?

• Carbon dioxide dissolved in the oceans, forming a weak acid that reacted with the minerals in the ocean to form a precipitate,

• Over time this formed sedimentary of carbonate rock on the sea bed.

• Dissolved carbon dioxide forms corals and shells of organisms such as mussels.

• As the organisms died, the carbon dioxide formed limestone.

How did Oxygen levels increase?

2.7 billion years ago, photosynthetic algae formed, which used CO2 to produce Oxygen, meaning animals could evolve.

How is coal formed?

• Made up of dead ferns and trees

• That couldn’t be decomposed by bacteria in marshy areas due to lack of oxygen and acidic conditions.

• The plants get compressed under high pressures and temperatures to form coal.

How is crude oil formed?

• Made up of dead plankton.

• Plankton gets washed up in the mud on the sea bed, cannot decompose due to lack of oxygen

• Plankton gets compressed by sediment in high pressures.

How are natural gases formed?

• Made up of dead plankton.

• Similar formation as crude oils, though are mainly methane and found in deposits next to oils.

• Made up of carbon from fossil fuels when plants photosynthesise.

What are some examples of greenhouse gases?

Carbon dioxide

Methane

Water Vapour

What is the greenhouse effect?

• From the sun, short wavelength waves, such as UV and visible light enter the atmosphere.

• Some of the waves are reflected by the atmosphere.

• Most waves directly travel through the atmosphere and onto the earth’s surface, as short wavelength waves do not interfere with greenhouse gas molecules.

• The waves are then radiated out by the Earth’s surface, though most gets trapped by the greenhouse gas molecules, as longer wavelength waves interact with gas molecules.

• This trapped energy would ultimately heat up the earth’s atmosphere.

How could carbon dioxide increase?

• We use produce CO2 through burning using fossil fuels.

• Such as coal for electricity, diesel and oil for fuelling cars, and gases for heating homes.

• Carbon dioxide is also produced through deforestation - trees absorb CO2 through photosynthesis and is released when chopped down.

How could methane increase?

• Cow fart.

• During agriculture, such as growing wheat on flooded, padded land.

What are some dangers of rising climate change?

• Higher temps melts polar ice glaciers and sheets, rising sea levels and causing flooding.

• More storms in the UK

• Less distribution of insects and insect-borne diseases, such as malaria.

What is peer review?

Evidence containing theories that must be shared between scientists to avoid bias or invalid results.

Why is climate change difficult to model?

Change in climate is so complex, evidence produces speculation, it causes oversimplification in the media, or even bias.

This means scientist must work harder to communicate ideas of the future of climate change.

Definition of carbon footprint.

The total volume of carbon dioxide or other greenhouse gases that are emitted during the full life cycle of a product, service, or event.

3 ways we could reduce Carbon Dioxide production?

• Heating our homes (Natural Gas): We could use insulation to prevent heat loss, or just turn down the heating.

• Driving cars (Oil, diesel): We could use public transport or trains, as this would decrease carbon dioxide per passenger.

• Producing electricity (Coal): We could use renewable energy sources, such as wind or solar power. We could also switch plugs off, instead of leaving them on standby.

Why are CO2 reduction methods unfavoured?

• Expensive, people are reluctant to pay.

• Inconvenient, people will not be willing to take public transport in place of driving themselves.

2 ways we could reduce Methane?

• Agriculture: Cows fart produces methane, we could reduce consumption of dairy products or beef.

• Landfill: Decomposition of landfill waste produces methane, we could trap the methane and burn it for electricity - great idea as methane is a stronger greenhouse gas than CO2.

Why are methane reduction methods unfavoured?

• People will not be willing to change their diet and people enjoy eating beef.

• Burning methane is expensive.

How is water vapour and Carbon dioxide formed from combustion of fuels?

In fuels, such as coal, when the fuel is combusted they release carbon and hydrogen that gets oxidised with the oxygen air particles.

This leads to increased greenhouse gases in the air which leads to climate change.

CH4 + 2O2 → CO2 + H2O

How is sulphur dioxide and NOx produced from combustion?

When coal is burnt it releases sulphur which gets oxidised to form sulphur dioxide.

In car engines, nitrogen is produced, under high temperatures many forms of oxides of nitrogen from, which scientists call ‘NOx’.

Why are NOx and Sulphur dioxide harmful?

• Breathing problems

• Dissolves in rainwater to form acid rain which is harmful to trees, and corrodes buildings made of limestone.

What are particulates?

Carbon particles and unburned hydrocarbons

Why are particulates harmful?

• Cause lung disease

• Heart disease

How do particulates affect the climate?

Particulates reduce the amount of energy from the sun that reaches the earth surface, causing global dimming.