Threats to Fragile Environments (Edexcel IGCSE Geography): Flashcards
Exam code: 4GE1
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Define fragile environment.
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Define fragile environment.
A fragile environment is an environment that is vulnerable to change and may struggle to recover from any damage.
All environments are a balance between the (biotic) and (abiotic) components.
All environments are a balance between the living (biotic) and non-living (abiotic) components.
True or False?
Human activity is the only cause of damage to fragile environments.
False.
Damage to fragile environments can be caused by both natural events (such as volcanic eruptions or tropical cyclones) and human activity.
Give one reason why arid and semi-arid environments are considered fragile.
Arid and semi-arid environments are considered fragile because the lack of precipitation and moisture reduces the environment's ability to recover if damaged.
Why are tropical rainforests considered fragile environments?
Deforestation and wildfires clear large areas, and the infertile soils make it difficult for plants to re-establish.
Why are cold environments slow to recover from damage?
The low temperatures reduce the environment's ability to recover because plants cannot regrow.
What two threats make coral reefs a fragile environment?
Coral reefs are killed by pollution and damage from tourists, and are vulnerable to warming oceans, after which the coral struggles to re-establish.
A change to one ______ in an environment can affect some or all of the others, upsetting the balance.
A change to one component in an environment can affect some or all of the others, upsetting the balance.
Which global process affects all fragile environments?
All fragile environments are impacted by the changes in climate caused by global warming.
True or False?
Arid and semi-arid environments have deep, fertile soils.
False.
Arid and semi-arid environments have shallow and infertile soils, which is one reason they struggle to recover from damage.
Damage to fragile environments can be caused by natural events such as ______ and tropical cyclones.
Damage to fragile environments can be caused by natural events such as volcanic eruptions and tropical cyclones.
Define deforestation.
Deforestation is the felling and clearance of trees.
Which three countries are currently experiencing the highest levels of deforestation in the world?
Brazil, Democratic Republic of the Congo and Indonesia are experiencing the highest levels of deforestation in the world.
True or False?
Wildfires are a natural cause of deforestation.
True.
Wildfires are a natural cause of deforestation, and their frequency and severity have increased due to climate change.
The six main human causes of deforestation include hydropower, mining, agriculture, settlement, timber, and .
The six main human causes of deforestation include hydropower, mining, agriculture, settlement, timber, and roads.
Define desertification.
Desertification is caused by both natural factors and human activities, which lead to the degradation of land in arid areas.
What is one way that reduced vegetation contributes to desertification?
Reduced vegetation means that nutrients are not added to the soil through decomposition, which contributes to desertification.
Overgrazing leads to being removed, which makes it harder for land to recover and increases the risk of desertification.
Overgrazing leads to vegetation being removed, which makes it harder for land to recover and increases the risk of desertification.
How does deforestation contribute to desertification?
Deforestation removes shade and roots that bind the soil together, increasing soil erosion, reducing infiltration and interception, and thereby promoting desertification.
How does over-cultivation cause desertification?
Over-cultivation leads to all the nutrients in the soil being used, so plants can no longer grow.
______ puts increased pressure on the land as people raise more animals and grow more crops, contributing to desertification.
Population growth puts increased pressure on the land as people raise more animals and grow more crops, contributing to desertification.
How have changing rainfall patterns contributed to desertification?
Rainfall has become less predictable, leading to drought, and any rain that falls is often in short, intense bursts that increase surface runoff and soil erosion.
True or False?
Desertification is caused only by human activities.
False.
Desertification is caused by both natural factors and human activities, and many natural causes are made worse by climate change.
Define Quaternary period.
The Quaternary period is the most recent geological time period, lasting the last 2.6 million years, during which there have been many cold (glacial) and warmer (interglacial) periods.
Evidence for past climate changes can be found in ice cores, preserved pollen, tree rings, and .
Evidence for past climate changes can be found in ice cores, preserved pollen, tree rings, and historical sources.
What effect do large-scale volcanic eruptions have on global climate?
Large volcanic eruptions release vast amounts of ash into the atmosphere, which can block solar radiation and lead to a decrease in global temperatures.
True or False?
Increased sunspot activity is linked to higher average temperatures on Earth.
True.
Periods of increased sunspot activity correspond with times of higher average temperatures on Earth.
Define greenhouse effect.
The greenhouse effect is the process by which greenhouse gases in the atmosphere trap long-wave radiation (heat), keeping Earth's average temperature suitable for life.
The average global temperature has increased by over since pre-industrial times due to the enhanced greenhouse effect.
The average global temperature has increased by over 1°C since pre-industrial times due to the enhanced greenhouse effect.
Which gas is released in large amounts from burning fossil fuels and is the main cause of the enhanced greenhouse effect?
Carbon dioxide (CO₂) is released by burning fossil fuels and is the main gas responsible for the enhanced greenhouse effect.
What is a tipping point in the context of climate change, as defined by the IPCC?
A tipping point is a critical threshold beyond which a system reorganises, often abruptly and/or irreversibly, leading to potentially large and permanent changes in the climate.
Define Milankovitch cycles.
Long-term changes to the Earth's orbit, tilt and wobble that alter how much solar radiation the Earth receives.
What would Earth's average temperature be without the greenhouse effect?
Without the greenhouse effect, the average temperature would be -18°C.
Greenhouse gases allow ______ radiation from the sun to reach the Earth's surface, which is re-radiated as long-wave radiation.
Greenhouse gases allow short-wave radiation from the sun to reach the Earth's surface, which is re-radiated as long-wave radiation.
Name one natural source of methane.
Methane is emitted naturally from oceans and soils during decomposition; termites also emit methane.
Atmospheric carbon dioxide has risen to ______ ppm in 2020, an increase of more than 100 ppm.
Atmospheric carbon dioxide has risen to 420 ppm in 2020, an increase of more than 100 ppm.
True or False?
A more elliptical orbit of the Earth leads to cooler periods.
False.
A more circular orbit leads to cooler periods, while an elliptical orbit leads to warmer periods.
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