2.1
What is global dimming.
A worldwide decline of the intensity of sunlight reaching the Earth's surface, caused by particulate air pollution & natural events eg. volcanic dust from eruptions.
Explain the term "feedback loops".
Feedback mechanisms that play a key role in controlling the earth's atmosphere.
Explain how global dimming could be interpreted as an example of negative feedback.
Global dimming could be regarded as a form of negative feedback. The use of fossil fuels can lead to increased temperatures due to more carbon dioxide in the atmosphere. However, the increased volume of pollutants in the atmosphere, provides many more smaller pollutants for water to bind to. The increased number of water droplets reflects more sunlight and so reduces the rise in global temperature.
Comment on the main contributors (types of countries) to emissions of greenhouse gasses.
Mostly MICs with some HICs like USA. Over half of the countries that have a high population and are involved in lots of agriculture and industry emit high amounts of GHG such as India and China. NICs that are rapidly urbanizing like mexico, India.
Explain how polluted air leads to global dimming.
Polluted air contains far more particles than clean air, such as ash, soot, sulphur dioxide. It provides many more surfaces for water to bind to. The droplets formed tend to be smaller than natural droplets, which means that polluted clouds contain many much smaller water droplets than naturally occurring clouds. Many small water droplets reflect more sunlight than fewer larger droplets, so polluted clouds reflect far more light back into space, thus preventing the Sun's heat from getting through to the Earth's surface and leading to global dimming.
State the cloud type that is most effective at reducing the amount of solar radiation that the Earth receives.
Stratocumulus is the cloud type that reflects most insolation. Thick clouds
Describe the change in albedo ice as ice melts and is replaced by soil/bare rock. (2 marks)
The albedo will get lower as the white and bright ice melts and exposes the bare dark rock. A change in colour from a light surface to a dark surface means the dark surface absorbs more heat/insulation, due to the decreased amount of albedo, therefore warming up the earth surface.
Describe the main impacts of Mt Pinatubo on mean global temperature.
The eruption of Mount Pinatubo lead to a sudden global decline in temperature of about 0.3°C in 1991-92. The decline in mean temperature fell from about 0.15°C to 0.1°C by 1997 and continued until at least 2005.
Identify the main types of radiation emitted by (a) the Sun and (b) the Earth.
a) Sun - Shortwave radiation b) Earth - Long wave radiation
Explain what terrestrial albedo is.
- Albedo: the proportion of solar radiation that is reflected back into atmosphere from a surface. - Reflectivity is GREATER with lighter surfaces (ice/snow): sunlight radiated back into atmosphere where heat is absorbed by atmosphere. - Reflectivity is LESS with darker surfaces (oceans/ bodies of water):heat from sun absorbed onto Earth's surface.
Describe one terrestrial albedo change and its feedback loop.
- An example of a terrestrial albedo change and its associated feedback loop occurs with the melting of snow and ice. As air temperature increases, there is increasing melting of ice caps and snow-covered areas. This replaces a highly reflective surface with a darker surface (albedo change), which absorbs more solar radiation, and reinforces the rise in temperature. - Positive feedback loop: albedo means light and bright surfaces absorb more sunlight and this radiates heat back into space. ↳more ice coverage melts leading to a rise in sea levels. ↳More ocean cover means more heat will be absorbed by the dark oceans. ↳PFL as the average global temp rises as a result of albedo.
What is the atmospheric energy balance.
- Atmosphere is an open energy system receiving energy from sun & Earth - Incoming solar radiation is called insolation - Solar energy drives all weather systems - Earth absorbs most energy in tropical regions - loss of energy from temperate & polar regions - To compensate for this, there is a redistribution of energy from lower latitudes to higher latitudes, driven by wind circulation & ocean currents.
How do GHGs work?
- Atmosphere: by day serves as a shield blocking out harmful & energetic sun rays & ⅓ of less intense visible light - At same time it traps the infrared radiation (heat) radiating out from the Earth's sun-warmed surface keeping us from freezing at night - For our atmosphere to absorb any type of radiation electrically charged particles are needed for passing electromagnetic waves - Most of atmosphere made up of gas molecules that don't have an electric charge - They have a balanced number of + & - charged electrons - Water, ozone, nitrous oxide are lopsided as some of their - charged electrons have more on one side - they move back and forth so can absorb incoming infrared energy more easily - C02 & methane are gas molecules that are constantly moving so lots of collisions occur causing each other molecule to become electrically lopsided when they bounce off each other - allowing them to absorb infrared rays and help them insulate the Earth.
Explain the terms "convection" "conduction" & "radiation".
- Convection: the transfer of heat by the movement of a gas or a liquid. - Conduction: the transfer of heat by contact. - Radiation: emission of short waves & long waves.
Suggest how globalization is linked to the enhanced greenhouse effect.
- Increased emission of GHGs due to the burning of fossil fuels. - As globalization proceeds, there is increased industrialisation and trade. These release huge amounts of greenhouse gases as they operate. Many LICs and NICs are actively industrializing and adopting a consumer culture. Industrial activity among the NICs has great potential to add to atmospheric CO2. Nevertheless, the per-capita emissions in HICs are responsible for much of the growth in atmospheric CO2.
Outline the main sources of emissions that are contributing to the enhanced greenhouse effect.
- Methane (Ch4): cows, landfill, ocean beds, permafrost, rice paddies - CO2: Burning fossil fuels (coal, oil & gas) - CFCs: Fridges & aerosols in LICs - Nitrous Oxide (N2O): vehicle exhausts, fertiliser - H20 - water
Identify the main constituents of the Earth's atmosphere.
- Nitrogen - 78%, Oxygen - 21%, Argon - 0.9%, carbon dioxide, nitrous oxides, methane & ozone - 0.1% (trace gases).
Explain the enhanced greenhouse effect. [3]
- Occurs as a result of increased quantities of greenhouse gasses in the atmosphere owing to human activities and their impact on these fragile atmospheric systems. - The problem we now face is that human activities - particularly burning fossil fuels (coal, oil and natural gas), agriculture and land clearing - are increasing the concentrations of greenhouse gases. This is the enhanced greenhouse effect, which is contributing to warming of the Earth.
Using an example describe the effect of positive feedback on global climate change.
- Positive feedback loop: MORE METHANE being released into our atmosphere. As the ice and permafrost melts in the tundra the underlying methane from the organic material below the ice is being exposed to the atmosphere. - Methane is found naturally, under the ice in tundra, underground and below sea bed. - Methane from cows is natural but the vast amount of cows is a major problem and is human induced. - Increased atmospheric methane adding to GHGs being trapped in atmosphere and warming the climate.
What is the atmospheric energy budget.
- Recent imbalance between inputs (insolation) & outputs (re - radiation) when the Earth receives solar energy - GLOBAL WARMING - Unnatural causes: human activities with fossil fuels & land use - NATURAL CONDITIONS: Radiation, Convection, Conduction
Explain why the Earth has a warmer climate than the moon.
- The Earth's atmosphere contains greenhouse gases whereas the soon's does not. Greenhouse gases allow short-wave radiation to pass through but trap some of the outgoing longwave radiation. This heats up the atmosphere, and the Earth's atmosphere is about 33°C warmer than the moon's. - The moon is an airless planet that has no greenhouse gasses so the greenhouse effect that keeps Earth habitable cannot occur. Global warming cannot occur in the moon for this reason.
Distinguish between the greenhouse effect and global warming.
- The greenhouse effect is the process by which certain gases (greenhouse gases) allow short- wave radiation from the Sun to pass through the atmosphere but trap an increasing proportion of outgoing long-wave radiation from the Earth. This radiation leads to a warming of the atmosphere. - In contrast, global warming is an acceleration of the greenhouse effect, caused largely by human production of greenhouse gases. It is also called the enhanced greenhouse effect.
Explain the natural greenhouse effect. [3 marks]
- The greenhouse effect is the process by which certain gases (greenhouse gases, such as water vapour, carbon dioxide and methane) allow short-wave radiation from the Sun to pass through the atmosphere but trap an increasing proportion of outgoing long-wave radiation from the Earth. This radiation leads to a warming of the atmosphere. - Process where water vapour, C02, CH4 & CFCs allow SW energy from the sun to pass through the atmosphere and heat up the earth. However some of the resultant LW radiation is trapped leading to a heating of the earth. - The greenhouse effect is a natural process that warms the Earth's surface. When the Sun's energy reaches the Earth's atmosphere, some of it is reflected back to space and the rest is absorbed and re-radiated by greenhouse gases. - The absorbed energy warms the atmosphere and the surface of the Earth. This process maintains the Earth's temperature at around 33 degrees Celsius warmer than it would otherwise be, allowing life on Earth to exist. > Step 1: Solar radiation reaches the Earth's atmosphere - some of this is reflected back into space. Step 2: The rest of the sun's energy is absorbed by the land and the oceans, heating the Earth. Step 3: Heat radiates from Earth towards space. Step 4: Some of this heat is trapped by greenhouse gases in the atmosphere, keeping the Earth warm enough to sustain life. Step 5: Human activities such as burning fossil fuels, agriculture and land clearing are increasing the amount of greenhouse gases released into the atmosphere. Step 6: This is trapping extra heat, and causing the Earth's temperature to rise.
Distinguish between the natural greenhouse effect and global warming (2 marks)
- The natural greenhouse effect is the beneficial/essential for life on earth whereas the enhanced greenhouse effect is leading to global warming and is causing the world to overheat along with many other impacts. > Award [1 mark] for each valid point. For example: The greenhouse effect is a natural effect [1 mark], in which certain gases (water vapour, carbon dioxide, methane and chlorofluorocarbons (CFCs)) allow short- wave radiation from the sun to pass through the atmosphere and heat up the Earth, but trap an increasing proportion of long-wave radiation from the Earth [1 mark]. This radiation leads to a warming of the atmosphere. In contrast, global warming is the increase in temperatures around the world that has been noticed since the 1960s, and in particular since the 1980s [1 mark], largely as a result of human activities [1 mark].
How do volcanic eruptions change Earth's climate?
- Volcanoes spew ou gases such as sulphur dioxide that enter the stratosphere and mix with water. ↳tiny sulphate particles formed ↳reflects some sunlight into space & surface below cools and & absorbs some sunlight warming up stratosphere - Big knock on effect: cooler surface = less evaporation = less rainfall - Warmer stratosphere -> warmer jet streams - 3% drop in rainfall after Mt Pinatubo eruption & cooled atmosphere by 1%
Explain negative feedback in relation to increases Co2 emissions.
> Negative feedback loop: these are good & bring loop/situation back to equilibrium. Produces long term stability in a system. - Increase of CO2 in atmosphere -> increased GHE & warmer temp -> increased evaporation from oceans -> increased cloud cover & albedo -> decreased temperatures -> back to equilibrium. - Increase of CO2 in atmosphere = increase in plant growth = increase in plant biomass productivity = increased store of carbon = DECREASE in concentration of CO2 in atmosphere.
Explain positive feedback and how a decrease in terrestrial ice coverage can cause positive feedback loops to occur.
> Positive feedback loop: they are BAD & lead to an increase change in average temp. When an increase in one phenomenon results in an increase in another. - Higher temperatures are resulting in the melting of polar ice caps meaning less ice and this lowers planetary albedo. - Ice is more reflective than water, less ice means less reflection - Lowering albedo increases the amount of solar energy absorbed by the Earth's surface & an increase in average temp. > More ice melts due to global warming increasing Earth's albedo which would then decrease warming.However as ice cover decreases less light is reflected back into space causing further warming.
Use example to explain why albedo and its effects vary.
> The term albedo means reflectivity. Light surface reflect more insolation whereas dark surfaces absorb more. For example, fresh snow has an albedo of 75-90% whereas a black road surface has an albedo of 5-10%. - Brighter and whiter surfaces are more reflective than darker surfaces. Ice reflects more sun radiation into atmosphere and dark surfaces like forests and oceans absorb heat. The type of surface
State and explain 4 anthropogenic cause of global warming.
>Burning of fossil fuels - Rising consumptions of fossil fuels driving changes - More GHG particles can be trapped in the atmosphere and absorb more heat. Long wave radiation will heat the surface of the Earth even more. >Car exhausts - Nitrous oxides emitted are becoming trapped in atmosphere. >Deforestation - Prevents atmospheric CO2 from being absorbed as the area of forest decreases >Cattle farming - Methane emissions increasing due to masses of cattle farming for meat and dairy
