Topic 5: Climate Change Flashcards
How does NASA collect data about rising temperatures?
- weather station data
- satellite observations of sea surface temperature
- Antarctic research station measurements
What are some natural causes of rising temperatures?
- variations in solar activity
- fluctuations in ocean currents
- volcanic eruptions
How do ice cores help determine temperature?
- measurement of O-18 and O-16
- warmer climates have more O-18 because it is preferred in precipitation and evaporates
What are the conditions in peat bogs?
acidic, cool, anaerobic
Why do anaerobic conditions reduce decompositions?
- no oxygen so decomposing bacteria can’t respire so die
- digestive enzymes not present
- acidic pH reduces enzyme action
Why might peat bogs not provide any evidence sometimes?
layers destroyed or mixed
Why is pollen in peat bogs useful? (4)
- large amounts
- resistant to decomposition
- distinct pollen for diff species
- each species grows best in particular climate
How are insect records taken from peat bogs and why are they more useful?
- exoskeleton preserved in bogs
- populations respond faster to climate change so more accurate
What is dendrochronology?
dating of tree rings to the year they were formed to analyse climatic conditions during different periods
Is the spring growth dark or light? Why?
light because it’s wet and warm so wider xylem vessels
Is summer growth dark or light? Why?
dark because it’s warmer and dry so less growth and narrow xylem
What does dendrochronology tell us?
Wet years have wider rings so provides information about how much precipitation there was
What is the atmosphere?
a layer of gases surrounding a planet
Where is the Karman line?
thermosphere (between Earth’s atmosphere and outer space)
How does the atmosphere sustain life? (3)
- contains O2 for respiration, CO2 for PS
- ozone layer absorbs UV light, reducing genetic damage
- maintains stable average temp, sustaining life
How does the atmosphere maintain a stable temperature?
greenhouse effect
Describe the greenhouse effect
- Short wavelength solar radiation passes through atmosphere
- Some radiation absorbed, warming the Earth
- Some longer IR radiation reflected off the Earth’s surface
- Longer wavelength IR absorbed by greenhouse gases, increasing the Earth’s temperature
Which greenhouse gas has the biggest effect on GHE?
water vapour because it has a high specific heat capacity and can absorb the most heat energy
What is global warming potential (GWP)?
a relative measure of how much heat a green house gas traps in the atmosphere
What is global warming?
enhanced greenhouse effect due to an increased level of greenhouse gases
Is there a link between CO2 concentration and temperature?
correlation but no causation so no direct evidence
What does two data sets from different locations confirm?
that the trend is global
Why are there CO2 fluctuations?
photosynthesis high in summer and low in winter
summer: PS > R
winter: R > PS
Why are CO2 levels increasing? (2)
- increase in fossil fuel in combustion so growing energy demand
- deforestation (less PS)
What are the sources of methane? (4)
- anaerobic bacteria in marshes and rice paddies
- anaerobic bacteria in guts of ruminants
- decomposition of organic material
- leakage from gas pipes
Why are methane levels increasing? (3)
- increase in rice paddy fields due to demand for food
- increase in ruminant population due to demand for food
- increase in number of landfill sites
What are the sources of nitrous oxide? (2)
- combustion of fossil fuels
- denitrifying bacteria acting on nitrates
Why are nitrous oxide levels increasing? (3)
- increase in fossil fuel combustion
- increased use of nitrate fertilisers
- increased cultivation of soil
What is the source of ozone?
reaction product of car exhaust pollutants
Why is climate change science controversial? (5)
- science cannot prove theories
- alternative interpretations exist
- knowledge about climate is incomplete
- available data has limitations
- interpretation bias
What is a scientific theory?
a comprehensive explanation of some aspect of nature that is supported by a vast body of evidence and upon which predictions can be made
What are the ethical frameworks? (4)
- utilitarianism
- rights and duties
- virtuous life
- informed decisions
What is extrapolation?
an estimate outside the recorded or observed range
What assumptions are made when extrapolating?
- enough data to establish a trend
- present trend continues
What factors need to be taken into account to predict CO2 concentration? (5)
- price of fossil fuel
- Kyoto protocol
- clean technology
- amount of PS
- increase in population
What are climate models?
quantitative methods to simulate the interactions of the different factors to project future climate
What is albedo?
when solar radiation is reflected from snow and ice due to white surfaces
What are the limitations of climate models? (5)
- limited data
- limited knowledge on how climate works
- limiting computing resources
- not all factors considered
- changing factors
How are flora and fauna adapting to climate change?
- changes in distribution
- changes in development
- changes in life cycle
How is distribution of species changing? Why?
- species migrating north
- loss of habitats and food sources (not ideal conditions)
- competition with aliens species and changes in dominant species
What is an alien species?
non-native invasive species that reduce biodiversity through disease, competition or predation
What makes it easier for species to migrate?
- animals being motile
- plants being good at seed dispersal
What happens to rate of reaction when temperature increases?
- increases (doubles for every 10C increase)
- more collisions of substrate and enzyme due to higher KE
Why does rate of reaction decrease when temperature is increased too much?
- secondary and tertiary bonds break due to high vibration of molecules
- enzyme denatures, active site changes shape, no binding of substrate
How does climate change affect organisms’ life cycles?
metabolic reactions speed up/slow down so rate of growth increases/decreases
What happens when rainfall patterns change?
- affects development and life cycles of organisms (plants remain dormant for longer)
- affects distribution of species: more desert areas
What happens when seasonal cycles change?
- affects development and life cycles
- animals might give birth earlier because food is available earlier
- affects distribution of birds
Describe how populations develop over time to become constant
1 - Slow growth: few organisms
2 - Exponential growth: few limiting factors, little competition
3 - Growth slows: limiting factors, competition, death rate increases
4 - Balanced growth: death and birth rates balanced, carrying capacity
Describe how natural selection happens
1 - There is variation within species because they have different alleles from mutations
2 - Selection pressure: some individuals are better adapted and have beneficial features
3 - More likely to survive and reproduce, passing on alleles to offspring
4 - Overtime, frequency of beneficial alleles increases
Define evolution
change in allele frequency in a population over time
What are the selection pressures due to climate change?
- higher temperatures
- changes in precipitation
- earlier springs and later autumns
What is the role of the scientific community in evaluated evidence?
1 - Scientific journals to see if same results are obtained after experiment is repeated
2 - Peer review before publishing to make sure it’s valid and experiments are conducted well
3 - Conferences where other scientists can ask questions, information reaches wider audience, quicker
What is speciation?
formation of new species from existing ones through reproductive isolation
What are the stages of allopatric speciation?
1 - Populations are geographically separated and experience different conditions. No gene flow occurs
2 - Populations experience different selection pressures so allele frequencies change
3 - Reproductive isolation: over time, populations become genetically distinct so they can’t reproduce to produce fertile offspring.
What changes in alleles cause reproductive isolation?
1 - Temporal barriers: different mating seasons
2 - Mechanical: genitalia may not fit each other
3 - Behavioural: different courtship displays
What is sympatric speciation?
- different alleles due to mutations
- new phenotypes and alleles can be advantageous
- passed onto offspring
How can genomics provide evidence for evolution?
- DNA tech determines base sequence & used to make comparisons between organisms’ DNA
- All organisms evolved from a common ancestor
- Closely related organisms diverged more recently so they’ll have more similar DNA
How can proteomics provide evidence for evolution?
related organisms will have similar DNA sequences and therefore similar amino acid sequences
What are carbon sinks?
reservoirs that remove carbon from atmosphere and put it in organic/inorganic compounds
Describe the carbon cycle
1 - Carbon is absorbed in plants for PS and becomes C compounds in plant tissue
2 - Animals eat plants and decomposers eat dead organic matter
3 - Carbon returned to atmosphere by respiration
4 - Dead organic matter in ocean/peat becomes fossilised
5 - CO2 produced when fossil fuels are combusted
What are the reasons for increase in atmospheric carbon?
- fossil fuels
- deforestation
- volcanoes
- weathering of limestone rocks
- less CO2 absorbed by ocean
- increased decomposition
Explain how carbon dioxide is removed from the air into the ocean
dissolves into the water for carbon fixation by photosynthesis in phytoplankton
Why might atmospheric CO2 levels not have increased as much?
- more CO2 fixed in photosynthesis
- carbon sinks absorbing more
What is a biofuel?
carbon-neutral fuel derived from recent photosynthesis
What does carbon-neutral mean?
no net effect on CO2 levels
What are the pros of biofuels?
- reduce the use of fossil fuels
- keeps fossil fuel price lower
- carbon neutral
What are the cons of biofuels?
- destruction of forests releases stored carbon into atmosphere
- soil erosion
- loss of land for food production
Why might the production of biofuels not be carbon neutral?
- deforestation destroying carbon sinks and releasing stored carbon
- less plants means less PS so less CO2 removed
- burning trees produces CO2
- fossil fuels for transportation and production
