global warming → major implications for human civilisation. extreme weather phenomena like typhoons and tornadoes will become stronger and occur more frequently. parts of world currently fertile will quickly become arid and barren. rising sea levels from melting polar ice sheets and thermal expansion of ocean water.
Global Warming
trend of temperature increase is accelerating
Definition
global warming is the increase in average temperature of the earth’s surface due to increasing amounts of greenhouse gases in the atmosphere. #ChemistryDefinitions
Greenhouse Effect
radiation from sun reaches earth in variety of wavelengths.
- short wavelength radiation is absorbed by the earth and converted to long wavelength radiation
- some of this radiation escapes into space but remainder is trapped by greenhouse gases in atmosphere as heat.
- similar to how heat is trapped within a greenhouse to grow crops that require warmer temperatures.
- solar radiation reaches earths atmosphere. some of it is reflected into space and some of it passes through atmosphere and becomes heat
- as earths surface is warmed, some of the heat rises and escapes into space
- remaining heat is trapped in the atmosphere by greenhouse effect, further warming the planet
certain amt of greenhouse effect is essential to life on earth. if atmosphere did not trap heat, earth would be too cold to support life (e.g. mars and icy moons of outer planets) too strong greenhouse effect make earth very hot like planet venus, temp hot enough to melt lead fine balance needed to maintain planetary conditions that allow life to thrive
carbon dioxide makes up 0.04% of clean air by volume.
- most common greenhouse gas
carbon cycle regulates amt of carbon dioxide present in the atmosphere → human activities cause output of carbon dioxide to surpass its intake.
combustion of fossil fuels in factories, power plants, vehicles → major contributor of atmospheric carbon dioxide. clearing of forests for agriculture is also a large contributor to CO2 emissions.
- has added effect of reducing number of plants available to absorb and retain carbon
cattle are significant source of methane - even stronger greenhouse gas than co2.
- greenhouse effect of methane 80* as strong as carbon dioxide
| Greenhouse Gas | Major Sources |
|---|---|
| Carbon dioxide | combustion of fossil fuels in power plants, industries, vehicles. deforestation |
| Methane | waste gasses from cattle leakage from methane reservoirs under arctic tundra and from oceanic methane ice |
Climate Change + Consequences
climate - weather conditions over a period of time.
- influenced by ocean temp, wind speed and direction, humidity
Change in Rainfall Patterns
- caused by shifting wind patterns
- lush areas might begin receiving too little rain - turn into deserts
- other areas receive too much rain - flood more often
- fertile land become barren - no longer able to produce food, cause food shortages
Heat Waves
- some parts become too hot for humans to live in
- can make destructive wildfires more common - could destroy entire ecosystems
Tropical Storms
- warmer oceans = stronger such storms
- endanger human lives destroy property damage farmland due to increase in slat content brought by salt water
Ocean Warming and Acidification
- coral reefs - high temp - bleach and die
- reduces marine biodiversity as habitats are lost.
- population of fish species, which humans depend on, severely cut
- warmer ocean water - absorb carbon dioxide faster - forming carbonic acid - decrease pH of water.
- crustaceans (crabs, corals, oysters, plankton) - impacted.
- depend on carbonate minerals to form their shells.
- acidified water removes carbonate minerals from ocean via acid carbon reactions Acid + Carbonate
- existing shells might also dissolve - killing org / making them more vulnerable to injury and predation
Glacial Retreat and Melting Polar Ice Caps
- increase temp cause melt
- many comm rely on steady stream of melt water from glaciers for drinking + irrigation
- lives affected if glaciers deplete faster than replenished
- water level rise at first, but as ice depletes, rivers eventually dry up