Session 3: Climate Change Flashcards
Describe the albedo effect.
Albedo is the ability of a surface to reflect sunlight - light coloured surfaces have high albedo and reflect more, dark coloured surfaces have low albedo and absorb light more than reflect it. Global climate is linked with global albedo (earth’s ability to absorb/reflect light). E.g. Ice and snow have high albedo (north and south poles) and so less ice/snow caps means earth is absorbing more light and heat.
Describe ocean acidification.
The reduction of the pH of the ocean over an extended period of time due to increasing CO2 levels in the atmosphere because the ocean absorbs the CO2.
Describe the greenhouse gases that have the largest warming effect within the atmosphere.
Water vapour: not just clouds but mainly clouds, created via evaporation of water bodies and transpiration (removed via precipitation)
CO2: made by cell respiration and burning of fossil fuels (removed by photosynthesis and absorption by oceans).
Describe the other greenhouse gases (not CO2 and not water vapour) and why they are not considered larger contributors to global warming.
methane: emitted from waterlogged habitats like marshes and landfills, also a gaseous waste produced by ruminants
nitrogen oxides: released naturally by certain bacteria and also emitted in the exhaust of certain vehicles
They are minor greenhouse gases because they have less of an impact on global warming because they are in much smaller quantities compared to CO2 and water vapour.
What happens on Earth when it receives radiation from the sun?
The sun emits short wavelength radiation. 25% of it is absorbed in the atmosphere of Earth, with the ozone layer absorbing most of the ultraviolet. The remaining 75% is absorbed and converted to heat on the surface of the Earth. The Earth then re-emits radiation back into space but at longer wavelengths (mostly infrared (heat)). Very small amounts of radiation are reflected by the Earth and the atmosphere.
Between 70-85% of the re-emitted longer wavelength radiation is absorbed in the atmosphere before it reaches space - it is trapped by gases in the atmosphere, and some is re-emitted back to the earth’s surface causing global warming (this is the greenhouse effect).
Summarise the greenhouse effect.
The greenhouse effect is what maintains the Earth’s temperature to a habitable standard by first absorbing solar energy from the sun and heating the Earth’s surface. Energy not used to heat the Earth’s surface is reflected by clouds, aerosol gases, and the atmosphere, while other energy is absorbed by the atmosphere. The heated surface of the Earth then radiates infrared energy into the atmosphere where certain greenhouse gases trap the heat and reflect some of the radiation back to Earth, keeping the heat inside our atmosphere and maintaining a habitable temperature. Burning fossil fuels like coal, oil, and natural gas have led to greatly increased amounts of greenhouse gases in the atmosphere, and this impact on the planet’s temperature is referred to as the man-made, enhanced greenhouse effect. The more of the greenhouse gases there are, the more heat will be trapped in the atmosphere. This also means that the greenhouse effect has more of an impact, and hence, the planet’s temperature will increase.
What are the effects of the enhanced greenhouse effect on Earth?
More frequent extreme weather conditions (heat, waves, cyclones, more powerful tropical storms, etc.), some areas to become drought affected while others become prone to heavy rain, and changes to circulating ocean currents - which may cause longer El Nino (warming) and La Nina (cooling) events.
Describe CO2 in history (e.g. CO2 and temp correlation)
levels of CO2 in the atmosphere have corresponded closely with temperature over the past 800 000 years, and there is strong positive correlation between increasing fossil fuels emissions and rising atmospheric concentrations of CO2. About 40% of CO2 emissions have remained in the atmosphere, the rest has been absorbed by carbon sinks (mainly oceans).
