P2 9 Atmosphere

• nitrogen 78% • oxygen 21% • other 1% -> carbon dioxide 0.04% -> argon/ water vapour/ noble gases

• intense volcanic activity • produced water vapour and gases (largely carbon dioxide, as well as methane/ ammonia/ nitrogen) (similar to the current atmospheres of Mars+Venus)

• the earth’s early atmosphere contained water vapour • which condensed as the earth began to cool • formed rain clouds which precipitated to form oceans in basins

• CO2 dissolved in the ocean water 1. carbonates were precipitated (sank to bottom of ocean as solids) producing sediments, sedimentary rock formed - limestone (calcium carbonate) 2. algae (water plant) replaced CO2 with O2 by photosynthesis 3. dead plants / small organisms ‘locked up’ CO2 when they died+ compressed into fossil fuels / sedimentary rock • so CO2 levels decreased

• algae evolved 2 billion yrs ago (+ other plants) • replaced CO2 with O2 through photosynthesis -> increase % of oxygen in atmosphere allowed animal life to develop • died to form fossil fuels - locked up CO2

• early plant species (algae) replaced CO2 with O2 through photosynthesis, then oxygen reacted with ammonia in atmosphere to form nitrogen (+water) • nitrogen is unreactive so levels remain constant

• dissolved in oceans, carbonates precipitated as solids, form sedimentary rock at bottom of seabed (limestone) • animals eat plants containing CO2, carbon used to make bones/shells, left as remains when dead, bones/shells compressed by mud/rock to form sedimentary rock (limestone) • plants containg CO2 die, remains compressed by mud/rock, forms fossil (coal) • algae containing CO2 die, remains compressed by mud/rock, forms fossil (crude oil / natural gas)

• water vapour • methane • carbon dioxide

• greenhouse gases allow short wavelength radiation to pass through from Sun • earth absorbs short wavelength radiation, heat is radiated from earth as long wavelength (infrared) radiation • some of this radiation is absorbed by greenhouse gases, so atmosphere’s temp rises

• burning of fossil fuels for energy - releases CO2 • livestock and rice farming - methane released by animals during digestion / decomposed matter in flooded rice fields • deforestation - fewer trees replacing CO2 in atmosphere

• simplified models of the atmosphere don’t fully explain the theory - misleading • speculation - media reports may only present parts of evidence • media/opinions may be biased - eg. people from industries producing greenhouse gases will lie

• melting ice caps - polar habitat loss - extinction • extreme weather + change in precipitation patterns - damage to crops, interferes with animal breeding/migration patterns - food shortage, less biodiversity • rising sea levels - due to rising sea temp + land-based ice loss - coastal flooding, marine life extinction

the total amount of greenhouse gases emitted over the full life cycle of a product/person/service/event

• renewable energy sources - lower emissions -> biofuel - carbon neutral • energy-efficient appliances - conserves energy, reduces emissions • taxing emissions, companies don’t pay if they plant trees instead • carbon capture+storage - CO2 released by industry/energy production is stored underground • recycling - conservation of natural resources • reduce consumption eg. walking over driving

• countries rely on fossil fuels for profit • renewable energy sources are expensive+ unreliable • requires lifestyle changes - some unwilling

• carbon monoxide: incomplete combustion • particulates (soot - unburned hydrocarbons): incomplete combustion • sulphur dioxide: sulphur impurities in fuel reacting with oxygen • nitrogen oxides: nitrogen+oxygen in air is heated

• carbon monoxide: toxic gas, colourless/odourless so not easily detected • particulates: global dimming (block sunlight), respiratory problems (particles inhaled), cancer • sulphur dioxide: acid rain, respiratory problems • nitrogen oxides: acid rain, respiratory problems

hydrocarbon + oxygen -> carbon dioxide + water

hydrocarbon + oxygen -> carbon dioxide + carbon monoxide + carbon (soot) + water