Earth Sciences 2024
Earth Sciences Revision
The Earth Cycles:
· The four spheres that matter can cycle through
o Lithosphere – outermost layer of the earth – part of the earth’s crust
o Atmosphere – thin layer of gases that maintains and sustains life
o Hydrosphere – all of the earth’s water
o Biosphere – all living things on earth
· The processes that transfer carbon between spheres
o Geological carbon cycle – long cycle resulting in being locked in rocks (fossil fuels)
o Biological/physical carbon cycle – short cycle where the carbon cycles through photosynthesis and cellular respiration
· Carbon cycle diagrams
o Photosynthesis – plants absorb CO2 from the atmosphere and release oxygen in return
o Respiration – both plants and animals consume oxygen and organic matter to produce energy, releasing CO2 back into the atmosphere
o Decomposition – when organisms die, their bodies break down and release CO2 into the soil and atmosphere
o Combustion – the burning of fossil fuels releases stored carbon as CO2
o Ocean-atmosphere exchange - CO2 is exchanged between the two. Oceans can absorb CO2, where it can be stored and used by marine organisms.
o Sedimentation and burial – over long periods, organic carbon can be buried and stored in sedimentary rocks and fossil fuels
Greenhouse Effect and Global Warming
· The wavelengths of the electromagnetic spectrum
o Infrared
§ Longer wavelengths (the size of a needlepoint)
§ Some wavelengths penetrate the earth’s atmosphere
o Visible light
§ Middle wavelengths (size of protozoans)
§ All wavelengths penetrate the earth’s atmosphere
§ Visible light from the sun is absorbed by the surface of the earth and radiated back as infrared
o Ultraviolet
§ Shorter wavelengths (size of molecules)
§ up to 10% of UV light penetrates the earth’s atmosphere
· Examples of greenhouse gases (DON’T FORGET TO DESCRIBE MORE)
o Carbon dioxide (CO2)
§ Burning and usage of fossil fuels
§ agriculture
o Methane (CH4)
§ Escaping natural gas
§ Agriculture (livestock
o Nitrous oxide
§ Agriculture
o Water vapour
§ evaporation
o Ozone
§ Chemical plants
§ Gasoline pumps
§ Heat and sunlight causing chemical reactions
· The differences between short and long- wavelength radiation
o Short wavelengths
§ Shorter
§ Higher frequency
§ Higher energy
o Long wavelengths
§ Longer
§ Lower frequency
§ Lower energy
· The process of the natural greenhouse effect
o The Sun sends infrared, visible, and infrared light onto the Earth
o The visible light is absorbed off the surface and then reflected off the Earth as infrared radiation, going back into our atmosphere.
o The greenhouse gases in our atmosphere sometimes are hit by the infrared radiation and the radiation is absorbed and reradiated back towards Earth, trapping the heat.
· The causes of the enhanced greenhouse and how that leads to global warming
o Causes:
§ Burning of fossil fuels, releasing large amounts of CO2 into the atmosphere.
§ Deforestation, destroying the trees that are needed to absorb CO2
§ Agriculture, where livestock, particularly cattle produce large amounts of methane during digestion
o How it leads to global warming
§ More heat is trapped in the atmosphere due to the higher concentrations of greenhouse gases. (enhanced greenhouse effect).
§ The global temperatures are rising as more heat is retained in the atmosphere
· Weather, climate, global warming, and climate change
o Weather – the conditions in the lower part of the atmosphere at a given time or place
o Climate – the average weather conditions in a particular region over an extended period
o Global warming – increase in the earth’s temperature due to the presence of certain human-made gases
o Climate change – a change in global or regional climate patterns
· Maintaining an equilibrium of carbon dioxide
o Due to an increase in CO2, the carbon cycle is unbalanced, and the remaining carbon has nowhere else to go except into the atmosphere where it traps heat, which warms the planet.
· How global warming can affect life on earth
o Biodiversity loss
§ Climate change has disrupted the distribution and number of species – possible extinction.
§ Increased land temperatures isolating populations to live in certain places
o Agriculture
§ Increased periods of drought and disruption to rainfall
§ Rising temperatures result in decreased crop yield
o Rising sea levels
§ Higher temperatures causing ice sheets and glaciers to melt
§ The melting of land-based ice and thermal expansion of water = rising sea levels
§ Sea ice declining a rate of 13% every decade
o Natural disasters
§ Number of extreme weather events increasing
§ More extreme rainfall and wind
§ Cyclones reaching category 4-5 increased by 15% over the past 20 years – cyclones intensify over warm ocean waters
§ Destructive flooding and disappearing islands and coastlines
