2.1 Causes of global climate change Flashcards
What is the difference between the natural greenhouse effect and the enhanced greenhouse effect?
The natural greenhouse effect is the process by which certain gases (such as water vapor, carbon dioxide, methane and chlorofluorocarbons [CFS]) 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 process leads to the warming of the atmosphere.
On the other hand, the enhanced greenhouse effect is the increasing amount of greenhouse gases in the atmosphere, as a result of human activities (such as burning fossil fuels and deforestation), and their impact on atmospheric systems including global warming.
What are the greenhouse gases in the atmosphere?
Water vapor accounts for about 95% of greenhouse gases by volume and about 50% of the greenhouse
Carbon dioxide accounts for about 20% of the greenhouse effect but an increased proportion of the enhanced greenhouse effect
Methane is the second largest contributor to global warming, and its presence in the atmosphere is increasing at 1% per annum
What is the difference between global warming and global climate change?
Global warming is the increase in temperatures around the world that have been noticed since the 1960s whereas global climate change refers to the changes in the global patterns of rainfall and temperature, sea level, habitats and the incidence of drought, flood, storms resulting from changes in the earth’s atmosphere, believed to be caused mainly by the enhanced greenhouse effect
what is The global energy balance?
the balance between income solar (short wave) radiation coming from the sun and outgoing infared (long wave) radiation from the earth. This helps to regulate the earth’s climate.
can you outline the earths energy balance?
The sun emits short wave radiation, some of which is reflected and absorbed by clouds and the atmosphere
However, most of the incoming solar radiation is absorbed by the earth’s surface, with a small portion being reflected by the earth’s surface
The radiation that has been absorbed by the earth’s surface is converted into long wave infrared radiation, which is emitted by the earth’s surface
This outgoing long wave energy is mostly reabsorbed by the atmosphere and re-emitted back into space
However, some of the outgoing long wave radiation is absorbed by greenhouse gases in the atmosphere, which re-emit the radiation back to earth
The earth’s surface temperature increases as it absorbs this radiation
what are the two diffrent tyeps of feedback loops?
A positive feedback loop is a mechanism in which a change in the system will lead to an increase in the change, thus amplifying the system.
A negative feedback loop is a mechanism that brings a system back to equilibrium. In other words, if a change occurs in the system, it may lead to other changes however the system will be brought back to the way it was before the changes have occured
what is an example of a postive feedback loop?
ice and snow albedo feedback
Albedo refers to the amount of incoming solar energy that is reflected by the earth’s surface back to the atmosphere
Ice and snow have high albedo, meaning that they reflect a lot of the incoming solar radiation
As the earth’s temperatures increase, due to green house gases trapping heat that is radiated from the earth’s surface, the area of snow cover on the earth’s surface decreases
Ocean and land surfaces have a lower albedo, meaning that they reflect less of the incoming solar radiation
As more ocean and land surfaces become exposed, more incoming solar radiation is absorbed by the earth, which contributes to continued and accelerated warming
what is an example of a negative feedback loop?
Evaporation and clouds
As the surface temperature of the earth increases, as a result of greenhouse gases released from human activities, there are increased levels of evaporation from the oceans
The increase in evaporation results in more clouds forming in the lower atmosphere
These clouds reflect some incoming solar radiation back into space, thus decreasing the earth’s surface temperature as less heat is absorbed
what causes varuations in how much sun output (solar radiation) reaches the earth, and what migh this lead too?
Data collected over the past several years suggest that global temperatures have fluctuated over time. The total amount of solar radiation reaching the earth can very due to changes in the sun’s output, the presence of aerosol particles in the atmosphere and changes in the earth’s orbit: Global dimming
Sunspot activity:
Milankovitch cycles:
can you expand on global dimming for solar radiation variations?
Global dimming refers to a reduction in the amount of incoming solar energy received from the sun, resulting from an increase in the presence of aerosol particles in the atmosphere, which is caused by pollution, dust and volcanic eruptions
These particulates act as condensation nuclei for water droplets that form clouds. However, the droplets are more numerous and smaller than droplets in natural clouds, and they reflect more sunlight. This prevents some sunlight from reaching the earth’s surface and thereby reduces some of the impact of the enhanced greenhouse effect.
can you expand on sunsport activity for solar radiation variations?
Sunspots are small dark spots on the surface of the sun that emit high amounts of solar output
The presence of sunspots can can raise global temperatures and their absence may decrease temperatures
can you expand on mylankovich cycles for solar radiation variations?
variations in the tilt and/or orbit of the Earth around the sun leads to different parts of the earth getting more or less sunlight
The angle of title on the Earth’s axis changes over 41,000 year cycle. This causes more or less sunlight to reach the poles
Earth’s orbit around the sun varies between a perfect sphere and an ellipse. When this orbit is an ellipse, less sunlight reaches the earth at certain points in its orbit, cooling the climate
can you discribe variations in greenhouse gas emmisions generally?
In general, it can be seen that countries in the northern hemisphere emit more carbon dioxide annually in comparison to countries in the Southern Hemisphere. For example, China emitted up to 10 billion tonnes of carbon dioxide in 2017. On the other hand, Argentina emitted approximatley 100-250 million tonnes of carbon dioxide in 2017. However, Greenland is an anomaly as it is located in the northern hemisphere and only emitted up to 50 million tonnes of carbon dioxide in 2017.
In general, in Africa, all countries emit less than 1 billion tonnes of carbon dioxide annually. Countries in Northern Africa emitted the most carbon dioxide in 2017, with Egypt and Algeria emitting approximately 100-250 million tonnes in 2017. On the other hand, countries in central and Southern Africa emitted less than 50 million tonnes, including Ethiopia and Madagascar. However, South Africa is an anomaly as it emitted approximately 250-500 million tonnes of carbon dioxide in 2017.
why do HIC have such high greenhouse gass emissions?
High income countries have high energy requirements due to domestic consumption and industry. For example, in terms of domestic energy consumption, a lot of energy is utilized for lighting, heating and washing and drying as household are able to afford them and afford products that utilize a lot of energy such as televisions. However, HICs are beginning to implement strict environmental laws, in order to reduce their greenhouse gas emissions, and are switching to relatively expensive new technologies in order to produce renewable energy with little to no emissions.
what explains the leve of greenhouse gasses MIC relises?
Middle income countries generally have manufacturing industries. This means that industrial energy use is quite high. However domestic energy consumption is lower in comparison High income countries.
