Climate Change (DP IB Biology)
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What is anthropogenic climate change?
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What is anthropogenic climate change?
Anthropogenic climate change is the warming of the atmosphere that is caused by human activities.
What are greenhouse gases?
Greenhouse gases are gases that absorb radiation re-emitted from the earth's surface, trapping it in the atmosphere and contributing to the greenhouse effect.
True or False?
Carbon dioxide and methane are examples of greenhouse gases.
True.
Carbon dioxide and methane are both greenhouse gases that contribute to the greenhouse effect.
What human activities have caused an increase in atmospheric carbon dioxide?
Human activities that contribute to increased carbon dioxide levels are:
burning fossil fuels
deforestation
peat bog destruction
What human activities have caused an increase in atmospheric methane?
Human activities that contribute to increased atmospheric methane include:
farming cattle
disposing of waste in landfill sites
extraction of fossil fuels from underground
growing rice in paddy fields
What is a positive correlation? (NOS)
A positive correlation is a relationship between two variables where an increase in one variable corresponds with an increase in the other variable.
What is a negative correlation? (NOS)
A negative correlation is a relationship between two variables in which an increase in one variable corresponds with a decrease in the other variable.
What is the difference between correlation and causation? (NOS)
A correlation is an association between variables while causation is when a change in one variable causes a change in the other.
What does the graph show about the relationship between atmospheric carbon dioxide and average global temperatures? (NOS)
Th graph shows that there is a positive correlation between atmospheric carbon dioxide and average global temperatures over hundreds of thousands of years.
Note that this graph alone is not enough to show that one variable has caused the change in the other.
True or False?
There is not enough evidence to show that increased atmospheric carbon dioxide and increased global temperatures are causally linked. (NOS)
False.
There is enough evidence to show that increased atmospheric carbon dioxide and increased global temperatures are causally linked.
What is positive feedback?
Positive feedback is a mechanism that leads to increased change away from a normal state.
Why is global warming an example of a positive feedback cycle?
Global warming is an example of a positive feedback cycle because global warming causes changes that lead to more global warming.
True or False?
Melting polar ice caps increase Earth's overall albedo.
False.
Melting polar ice caps decrease Earth's albedo, leading to more absorption of solar energy.
How do wildfires contribute to the positive feedback cycle of global warming?
Wildfires contribute to the positive feedback cycle of global warming as follows:
atmospheric carbon dioxide is increased during wildfires due to combustion of plant material and reduced photosynthesis
global warming increases
wildfires become more likely to to higher temperatures
True or False?
Peat bogs always release carbon dioxide.
False.
Peat bogs only release carbon dioxide when decomposition increases due to warming. When stable they function as carbon sinks.
What is the connection between increased activity of microorganisms and increased global warming?
The connection between increased activity of microorganisms and increased global warming is as follows:
increased decomposition in peat bogs and permafrost releases carbon dioxide as temperatures increase
increased activity of methanogenic microorganisms releases methane as permafrost melts
True or False?
Boreal forests always act as carbon sinks.
False.
Boreal forests can switch from being carbon sinks to carbon sources; this tipping point occurs due to the effects of global warming.
What is the primary cause of reduced water availability in boreal forests that occurs due to global warming?
The primary cause of reduced water availability in boreal forests due to global warming is reduced snowfall due to increased temperatures; this reduces the water available from snow melt.
Define the term forest browning.
Forest browning is the process during which trees lose their green pigment and turn brown due to drought caused by global warming.
What is legacy carbon combustion?
Legacy carbon combustion is the release of carbon that has been locked up for many years in living trees, dead needles on the ground, and within the soil itself, typically through forest fires.
How does global warming affect Emperor penguins?
Global warming affects emperor penguins by causing earlier melting of sea ice; this reduces the time that Emperor penguins have to raise their young on the Antarctic sea ice where they breed.
How does early loss of Arctic sea ice affect Walruses?
The early loss of Arctic sea ice forces walrus mothers to care for their young further from the water's edge, leaving young without protection for longer periods when the mothers hunt for food.
How do changes in ocean currents due to global warming affect energy flow through food chains?
Changes to ocean currents due to global warming can prevent normal nutrient upwellings from the deep ocean. This reduces primary production and means that less energy is available to marine food chains.
How has global warming affected montane bird species in New Guinea?
Global warming has caused many bird species in the mountains of New Guinea to migrate to higher altitudes; this is an upslope range shift.
How has global warming affected North American tree species?
Global warming has caused range contraction and northward, or poleward, range shifts in North American tree species.
What is ocean acidification?
Ocean acidification is the process by which ocean pH decreases. This occurs when there is an increased in dissolved carbon dioxide, leading to an increase in H+ ions.
How does ocean acidification affect coral reefs?
Ocean acidification can weaken and dissolve the calcium carbonate exoskeletons of corals and reduce the availability of carbonate ions needed for building these structures.
True or False?
Ocean acidification is a direct result of global warming.
False.
While ocean acidification and global warming share the same cause (increased atmospheric carbon dioxide), ocean acidification is not a direct result of global warming.
What is coral bleaching?
Coral bleaching occurs when coral polyps expel their algae symbionts due to high water temperatures, causing reefs to lose their bright colours.
How does coral bleaching affect a coral reef?
Coral bleaching can result in death of coral polyps and the collapse of reef ecosystems.
Define the term carbon sequestration.
Carbon sequestration is the process of capturing and storing carbon dioxide from the atmosphere.
What is the difference between reforestation and afforestation?
Reforestation involves planting trees in deforested areas while afforestation is the creation of new forests on lands that have not been recently forested.
How can peat bogs be restored?
Peat bogs can be restored by:
filling in drainage ditches to restore peat to its waterlogged state
reducing the harvesting of peat to allow recovery
What are the two tree-planting approaches to carbon sequestration that are debated by scientists? (NOS)
The two approaches to carbon sequestration debated by scientists are:
planting non-native tree species that grow quickly and sequester carbon rapidly
rewilding with native species; this sequesters carbon more slowly but may benefit biodiversity