8.1 Climate change

• Greenhouse gases: gases in the atmosphere that absorb infrared radiation

  • e.g) Water vapour, CO2, CH4

  • CH4 is 28x more effective at holding heat than CO2

Human sources of greenhouse gases

• Combustion of fossil fuels (CO2 + water vapor): releases CO2 underground + into the atmosphere; created water vapor during combustion

  • Coal is the most polluting fossil fuel

• Rice & livestock farming (methane): methane is released when organic material is broken down

  • Rice farming in flooded fields blocks O2 from getting to the soil, which creates conditions for bacteria decomposing vegetation to release methane

  • Livestock eat vegetation → break it down & release methane

  • Deforestation for livestock → adds to CO2 levels

  • Warming climate → permafrost melts → releases CH4 → causes more permafrost to melt

• Landfill gas (methane): by-product of decomposition of organic material found in buried waste → releases CH4 + CO2

Enhanced greenhouse effect

• Increased amount of infrared radiation being retained in the atmosphere due to human activities, which increase GHGs in the atmosphere

Difficulties monitoring + predicting climate change

• Historical data: relies on limited amount of proxy data — relies on natural records from the environment

  • Ice cores: drill from deep in the ice; analyse for info on past temperatures, precipitation, volcanic activity etc.

  • Corals: build skeletons out of calcium carbonate; can determine water temperature at the time the coral grew

  • Tree rings: can determine climatic conditions at the time of tree growth; composition of rings reflect change in the climate

  • Historical accounts provide qualitative + quantitative data that can determine climate conditions of the past

• Computer climate models: use data on variables, like temperature & precipitation, to predict future climate; wide range of possibilities makes creating models difficult

• Climate feedback models: can speed up/slow down factors that drive climate change; difficult to predict the impact of feedback mechanisms on the climate — they aren’t fully understood & can be unreliable

• Time delay b/t cause and effect: can take years/decades to see the impact of increases GHGs

  • Can make computer modeling complicated & uncertain

• Data uncertainty: different opinions on future potential changes in the climate within the politics + science

8.2 The impacts of climate change

Environmental impacts

• Increase temperatures

  • Impact frequency + intensity of precipitation

• Sea level rise: melting land ice + ice sheets cause more water to enter the oceans

• Ocean circulation: disrupt ocean currents → can increase precipitation in N. Atlantic & melt polar ice sheets + glaciers

• Melting ice: reduced albedo effect = increased amount of solar energy absorbed, melting of permafrost = increased methane

• Species distribution and biodiversity: can alter habitats

Human impacts

• Increased frequency + severity of extreme weather, which causes: flooding, strong winds, loss of land + lives

  • Less precipitation + increases temps = drought + wildfires

• Forced migration: natural disasters make certain parts of the world difficult to live in, causing people to migrate

• Impacts on crop yields: can decrease due to increased temps + changes in rainfall patterns

  • Climate change can cause outbreaks of insects, like locusts, which decrease yield

• Threatens water + energy security:

  • Increased evaporation + fluctuating levels of precipitation (e.g. increase can spread disease)

  • Need to implement renewable energy sources to combat climate change, which can be challenging + cause energy insecurity

8.3 Managing climate change

• Reduction of global and individual carbon footprint

  • Fewer children per woman: lower carbon emissions + energy consumption

  • Plant-based diet: less CO2 emissions for transport + less CO2 & CH4 emissions by not eating meat

  • Energy-efficient lifestyle: timers on showers, energy-efficient light bulbs, etc

• Low-carbon fuels: lower carbon content than petroleum fuels (e.g. natural gas & biofuel)

  • Reduce CO2 emissions, BUT increased land use for biofuels (e.g. corn + sugarcane)

• Reducing the use of fossil fuels + individual (e.g. public transport) & gov’t (e.g. clean energy policies) actions

• Using alternative forms of energy (e.g. wind, solar, geothermal)

• Transport policies: need to consider reduction of CO2 emissions + improved fuel efficiency

  • Catalytic converters, sustainable biofuels (e.g. biogas), & improved public transportation

• Use of carbon capture and storage: capturing CO2 before it’s released into the atmosphere & storing it

  • Pre-combustion: before fossil fuels are burned → fossil fuels into CO2 and hydrogen

    • Requires significant modification to power plants

  • Post-combustion: removes CO2 after burning fossil fuels

  • Oxyfuel technology: burning fossil fuels with nearly pure oxygen, producing CO2 + steam

  • Technology is expensive & possible CO2 leakage at storage sites

• Reducing deforestation: reforestation/afforestation increase tree biomass + carbon stored

  • Cost-effective + improves water security (increased transpiration & less runoff, which recharges aquifers)

• Energy efficient buildings and infrastructure: take advantage of sun’s energy, well-insulated, low-energy consumption features

  • Passive buildings: eco-friendly; consume low amounts of energy + make use of energy sources in the building

• Adaptation to climate change

  • 

• National and international agreements:

  • Kyoto Protocol: reduce GHG emissions by acknowledging that global warming exists & human-caused emissions are the underlying cause

  • Paris Agreement: UN agreement addressing GHG emissions starting in 2020

Geo-engineering / Solar radiation management (SRM)

• Reflect some incoming solar radiation & limit the amount of energy trapped by GHGs

• Albedo enhancement: large pumps to introduce microbubbles into bodies of standing water & reflective films on top of the ocean surface

• Stratospheric aerosols: sulfate aerosols spray aerosol into the atmosphere into the stratosphere by using a tethered balloon, which reflects sunlight

  • Simple, inexpensive, & technologically feasible, BUT may cause drought/flooding, limited research available, untested, & short-term

• Space reflections: reflect incoming solar radiation rays before getting trapped in the atmosphere