Chapter 2 Gateway 2: Climate change Flashcards
What is global climate change?
The variation in the global climate or climate patterns in the long term
What does global climate change include?
- Major changes in temperature
- Wind patterns that occur over several decades or longer
What is global warming?
The increase in global temperatures over a long period of time
Since the 1800s, the earth has experienced a significant but irregular upward trend in temperature with fluctuations of 0.3 degree celsius to 0.6 degree cleo due
What are some natural causes of climate change?
- Variations in solar output
2. Volcanic eruptions
What is variation in solar output? Example?
The sun emits varying amounts of solar energy due changes in its magnetic field. Sunspots are cooler regions on the sun’s surface that appear as dark spots. During periods of intense solar magnetic activity, the number of sunspots increase, resulting in higher solar radiation. This is because the areas surrounding the sunspots radiate more energy, which compensates for the lower temperatures of the sunspot areas
Example: In 2000, it was recorded to have the highest number of sunspots observed of approximately 165. And this coincided with the high solar activity. Global temperatures also increased during this period
What happens when a volcano erupts?
When a volcano erupts, large volumes of carbon dioxide, water vapour, sulfur dioxide, dust and ash are released into the atmosphere. Sulfur dioxide reacts with water to form sulfur-based particles into the atmosphere. Together with dust and ash, these particles reflect solar energy back into space. This results in a cooling influence on global temperatures
What is an example of a volcanic eruption and give the description
Mount Pinatubo, Philippines, 1991
The eruption released 17 million tonnes of sulfur dioxide into the atmosphere, forming sulfur-based particles that speed around the earth in two weeks. The sulfur-based particles reflected solar energy back into space and lowered temperatures in the northern hemisphere by as much as 0.6 degree celcius
What is the greenhouse effect?
A process by which greenhouse gases trap heat in the atmosphere
This process keeps the atmosphere warm to sustain life on earth
How does greenhouse effect works?
- Incoming shortwave radiation from the sun passes through the atmosphere
- Some shortwave radiation is reflected by the earth and the atmosphere
- Most shortwave radiation is absorbed by the earth’s surface which then heats up as a result
- The warmed surface on the earth emits longwave radiation to the atmosphere
- The greenhouse gases absorb longwave radiation, warming the atmosphere
What are some examples of greenhouse gases?
Water vapour Carbon dioxide Nitrous oxide Methane Ozone Halocarbons
What happens when greenhouse gases absorb longwave radiation?
When greenhouse gases absorb longwave radiation, they re-radiate it in all directions. Some of this radiations escapes into space, but most of it is absorbed by other gas molecules in the atmosphere or by the surface of the earth
What is enhanced greenhouse effect?
An increase in the concentration of greenhouse gases in the atmosphere, leading to a rise on global temperatures
When does the enhanced greenhouse effect occurs?
The enhanced greenhouse effect occurs when human activity causes greenhouse gases to be released at a far greater rate than that of natural emissions of greenhouse gases
What are anthropogenic factors? What can they do?
Factors caused by human activities such as deforestation and changing land users
The concentration of greenhouse gases in the atmosphere has increased mainly due to anthropogenic factor
What is deforestation?
The loss of forests due to the removal or clearance of trees in forested areas
What does deforestation do to the earth?
Forests absorb billions of tonnes of carbon dioxide every year via photosynthesis. With fewer trees to absorb carbon dioxide, it leads to an increase in carbon dioxide levels in the atmosphere. In addition, deforestation exposes soil to the sunlight. This increases soil temperature and the rate of carbon oxidation in the soil. As such, deforestation increases the rate at which carbon dioxide is released from the soils into the atmosphere
What is an example of deforestation?
Between 2000 and 2010, 52000 square kilometres of forests was lost. The greatest overall loss of forests occurs in South America
Why are trees removed?
Trees are felled for wood to make products such as paper and building materials. Trees are also removed to clear the area for mining activities, the grazing of animals, the planting of crops and the construction of infrastructure
What does deforestation increase?
Deforestation increases the rate at which carbon dioxide is released from the soil into the atmosphere
What are examples of changing land use?
What is agriculture? What is the ranking of contributors of greenhouse gases?
The practice of cultivating land, producing crops and raising livestock
The third highest contributor of greenhouse gases
Why agriculture contributes to changing land use?
Cattle farming contributes to greenhouse gas emissions because millions of tonnes of methane are released each year by cattle as a waste gas. Methane is also released in rice fields where decomposition is very rapid due to the high level of moisture in the soil