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How do anthropogenic factors contribute to climate change?
1. Growth in population and industrialisation
a) altered quantity of greenhouse gases in the atmosphere including carbon dioxide, methane and nitrous oxide
b) data from the last decade has shown it to have been successively warmer than any of the preceding decade since 1850
2. Causes of the greenhouse effect
a) a natural process making Earth liveable
b) involves absorption and emission of shortwave and longwave radiation, respectively
3. Causes of the enhanced greenhouse effect, include
a) burning of fossil fuels
b) changing land use
Slider animation to show the increase in global surface temperature over time http://climate.nasa.gov/keyIndicators/#globalTemp .
Watch this animation http://earthguide.ucsd.edu/earthguide/diagrams/greenhouse/ on the greenhouse effect.
How much do you know of climate change? Complete the quiz below
Earth day Climate change quiz https://www.earthday.org/the-climate-change-quiz/
What is the greenhouse effect and how does it work?
Greenhouse effect is a natural process in which the gases in the Earth’s atmosphere trap longwave radiation emitted from the earth’s surface, warming the atmosphere. The earth receives shortwave radiation in the form of visible light from the sun. Some of the shortwave radiation is absorbed by the earth’s surface, which then heats up as a result. The earth’s surface then emits longwave radiation in the form of infrared radiation. The longwave radiation emitted from the earth’s surface is absorbed by the gases in the earth’s atmosphere.
Water vapour, carbon dioxide, methane, nitrous oxide ozone and halocarbons such as chlorofluorocarbons (CFCs) are good absorbers of longwave radiation. They are known as greenhouse gases and are found in the atmosphere.
Enhanced greenhouse effect
Enhanced greenhouse effect refers to an increase in the concentration of greenhouse gases in the atmosphere, leading to a rise in the global temperatures. The enhanced greenhouse effect occurs when human activity causes greenhouse gases to be released at a far greater rate than that of the natural emissions of greenhouse gases.
Concentrations of greenhouse gases such as nitrous oxide and methane have increased in the earth’s atmosphere since the Industrial Revolution in the mid-18th century. Among these gases, the most significant increase is in the amount of carbon dioxide.
How does land use changes lead to an increase in greenhouse gases and climate change?
Log onto https://www.iup.uni-bremen.de/sciamachy/NIR_NADIR_WFM_DOAS/wfmd_image_gallery_ch4.html
and scroll down to Map 9 and below
Study the series of satellite maps with colours indicating the level of methane emission over the following regions:
• China and India
• South America
• North America
• African continent
• Australia
Points to ponder:
• What are some activities associated with land use changes?
• What is the common staple food item in India and China?
• What is the agricultural activity in the Amazon region?
• How will the food items in (a) and (b) lead to methane emission?
• Why is methane a potent greenhouse gas?
• .How is population increase related to food production?
• How does increasing urbanization relate to methane emission from agriculture?
Points to ponder:
• Where on the Earth are the highest rates of methane emission found?
o NZ, Brunei, Australia, Uruguay, Paraguay (cattle rearing), East Asia, Southern Asia (rice growing)
• Are you surprised by the high level of emissions in those places?
o DCs are not always the only culprits of green house gas emissions!
o (Industries also emit methane and nitrous oxide, but agriculture is also a point of concern)
• Which countries or continents have the lowest rates of methane? Why?
o Singapore! UAE – urbanized, desert, low animal to land ratio.
• Does it mean that urbanized areas are not responsible for methane emission? Why not?
o In truth, every food item we consume, vegetables and fruits included, incurs hidden environmental costs: transportation, refrigeration and fuel for farming, as well as methane emissions from plants and animals, all leading to a build-up of atmospheric greenhouse gases.
• Methane just as lethal as 23 tonnes of CO2 over 100yrs.
Changing land use
As population increases, the demand for agricultural and industrial land also increases. Land is also converted to build-up areas as more people choose to live in cities.
Agricultural activities
The cultivation of rice in padi fields releases methane when organic matter such as dead leaves and manure are decomposed. Decomposition is very rapid in the rice fields due to the high level of moisture in the soil.
The use of inorganic fertilizers increases the amount of nitrous oxide in soil. Nitrous oxide is released when soil is plough or when rain flow through the soil.
Tractors running on fossil fuels also release carbon dioxide.
Cattle farming also contribute to greenhouse gas emissions because cattle release methane as a waste gas. Millions of tonnes of methane are released each year from cattle farming.
Methane from cattle ranching contributes to 30% of total greenhouse gas emission in Argentina according to the Telegraph published on 8 July 2008.
Industrial activities
With industrialization, the rapid increase in the use of fossil fuels in vehicles, factories and power plants has led to high levels of carbon dioxide and nitrous oxides being released into the atmosphere. The largest carbon dioxide emissions from industrial processes are found in North and Central America, Europe and Asia.
In recent years, countries like China and India are contributing more to global carbon dioxide emissions due to their rapid industrialization.
The usage of chemicals like Chlorofluorocarbons (CFCs) found in aerosol spray cans, refrigerators and air-conditioners, has also contributed to the increase in greenhouse effect.
Urbanisation
It is a process by which an increasing number of people live in urban areas such as cities and towns. Large amount of fossil fuels are burnt to provide energy for household activities in urban areas. These activities include heating, cooling, cooking and lighting. The high concentration of cars, buses and other forms of transportation in urban areas also contribute to the amount of greenhouse gases emitted in these areas.
As shown above, most of the changing landuse require the production of energy which is often generated through the burning of fossil fuels.
Due to their high carbon content, fossil fuels contribute to the increase in greenhouse gases by producing large amounts of carbon dioxide when burnt. The burning of fossil fuels is the highest contributor of greenhouse gases. In 2010, global carbon dioxide emissions totaled 30.6 billion tonnes, which was 5.6% increase from 2009.
Look at the report below on how urbanisation has contributed to the higher temperatures in Singapore:
http://www.todayonline.com/singapore/singapore-growing-warmer-twice-global-average Singapore getting warmer due to urbanisation
As a country become more urbanised, greater need for energy which involve burning of fossil fuels and releasing more carbon dioxide, a greenhouse gas. Greenhouse gases trap heat as it allows short wave radiation from the sun to pass through and not the long wave radiation emitted from the earth
Urban heat island effect in Singapore
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