4.4 Climate Change Flashcards
What do greenhouse gases absorb/emit and what is the consequence of this?
Greenhouse gases absorb and emit long-wave (infrared) radiation, thereby trapping and holding heat within the atmosphere
What % of the earth’s atmosphere is greenhouse gases?
Greenhouse gases collectively make up less than 1% of the Earth’s atmosphere
Which greenhouse gases have the largest warming effect?
The greenhouse gases which have the largest warming effect within the atmosphere are water vapour (clouds) and carbon dioxide
How is water vapour created/removed?
Water vapour is created via evaporation of water bodies (e.g. oceans) and transpiration – it is removed via precipitation (rain)
How is CO2 made and removed?
Carbon dioxide is made by cell respiration and burning fossil fuels – it is removed via photosynthesis and absorption by oceans
What greenhouse gases have a less severe warming effect?
Other greenhouse gases include methane and nitrogen oxides – these have less impact on the overall warming effect
How is methane emitted?
Methane is emitted from waterlogged habitats (like marshes) and landfills – it is also a gaseous waste produced by ruminants
How are nitrogen oxides emitted?
Nitrogen oxides are released naturally by certain bacteria and also is emitted in the exhaust by certain vehicles
How does water vapour differ from other greenhouse gases?
Water vapour is the most abundant greenhouse gas in the atmosphere, but is not produced as a product of human activity
What two factors influence the warming impact of a greenhouse gas?
ability to absorb long-wave radiation
concentration within the atmosphere
How does the ability to absorb long-wave radiation affect the warming impact of a greenhouse gas?
Gases that have a greater capacity to absorb long-wave radiation will have a greater warming impact (per molecule)
How does the Concentration within the atmosphere affect the warming impact of a greenhouse gas?
The greater the concentration of a gas, the greater its warming impact will be within the atmosphere
What determines the concentration of a gas in the atmosphere?
The concentration of a gas will be determined by both its rate of release and persistence within the atmosphere
How can the overall impact of a greenhouse gas be determined?
The overall impact of a greenhouse gas will be determined by the combination of both these factors
How does methane compare to CO2 in terms of ability to absorb long-wave radiation?
Methane has a larger capacity to absorb long-wave radiation than carbon dioxide, but is significantly less abundant
How does water vapour differ from CO2?
Water vapour enters the atmosphere rapidly but only remains for short periods, while carbon dioxide persists for years
How is human activity affecting greenhouse gases?
Human activity is increasing the amount of greenhouse gases (except water vapour) and hence increasing their impact
What is the greenhouse effect?
The greenhouse effect is a natural process whereby the atmosphere behaves like a greenhouse to trap and retain heat
What is the purpose of the greenhouse effect?
This ensures the Earth maintains the moderate temperatures needed by organisms to maintain life processes (homeostasis)
What would happen without the greenhouse effect?
Without a greenhouse effect, Earth’s temperatures would drop significantly at night in the absence of direct sunlight
What does the greenhouse effect maintain?
The greenhouse effect functions to trap heat within the atmosphere and hence prevent rapid temperature fluctuations
What radiation is emitted by sun?
Incoming radiation from the sun is shorter wave radiation (ultraviolet radiation and the visible spectrum)
What radiation does the Earth absorb?
The surface of the Earth absorbs short wave radiation and re-emits it at a longer wavelength (i.e. infra-red / heat)
What do greenhouse gases absorb and re-radiate?
Greenhouse gases absorb and re-radiate this longer wave radiation and hence retain the heat within the atmosphere
What two human activities increase greenhouse gas concentration?
deforestation and increased farming
How does deforestation affect greenhouse gas concentration?
the removal of trees means that less carbon dioxide is removed from the atmosphere via photosynthesis
How does increased farming affect greenhouse gas concentration?
Increased farming / agriculture – this involves land clearing for cattle grazing, also ruminant cattle produce methane
What greenhouse gas is increasing most rapidly and why?
The greenhouse gas that is increasing most rapidly in the atmosphere is carbon dioxide and the main cause is combustion
What happens when fossil fuels are combusted?
When fossil fuels (e.g. coal, oil, gas) are combusted to release energy, carbon dioxide gas is released as a by-product
How have CO2 levels changed over time?
The increased reliance on fossil fuels following the industrial revolution has resulted in ~38% increase in CO2 levels
What are we doing to reduce CO2?
There are now efforts to reduce our reliance on fossil fuels by exploiting alternative energy sources (e.g. solar power)
What do greenhouse gases play a role in?
Greenhouse gases play a pivotal role in determining global temperatures and climate patterns due to their capacity to retain heat
How does the greenhouse gas affect climate change?
As these gases trap heat, increases in greenhouse gas concentrations should correlate with an increase in global temperature
Apart from global temperature, what may be affect by the greenhouse effect?
Long term weather patterns (climate) may also be influenced by greenhouse gas concentrations
What 3 things do scientists predict with increasing greenhouse gas concentrations?
More frequent extreme weather conditions (e.g. heat waves, cyclones, more powerful tropical storms, etc.)
Some areas to become more drought affected, while other areas become more prone to periods of heavy rainfall
Changes to circulating ocean currents – which may cause longer El Nino (warming) and La Nina (cooling) events
How was the link between global temperatures and CO2 determined?
The link between global temperatures and carbon dioxide concentrations was established by analysing data over a long time period
What method may give us insight into past environmental conditions?
Ice cores taken from the Vostok station in Antarctica provide evidence of the environmental conditions at the time of freezing
What is the Vostok ice core?
The Vostok ice core is one of the longest drilled, reaching back 420,000 years and covering the past four glacial cycles
How are ice cores analysed?
By analysing the gas bubbles trapped in ice, historical CO2 levels and air temperatures (via oxygen isotopes) can be deduced
What point, in relation to CO2 and temperature, have the ice cores demonstrated?
There is a strong positive correlation between carbon dioxide concentrations and temperature (↑ CO2 levels ∝ ↑ temperature)
What point, in relation to cycles, have the ice cores demonstrated?
There have been fluctuating cycles of CO2 concentrations which appear to correlate with global warm ages and ice ages
What point, in relation to CO2 historical concentrations, have the ice cores demonstrated?
Current concentrations of CO2 are higher than at any time recorded in the last 400,000 years
What historical event triggered the use of fossil fuels?
The industrial revolution introduced new manufacturing processes which significantly increased mankind’s use of fossil fuels
What does the burning of fossil fuels release?
The burning of fossil fuels releases carbon dioxide as a by-product, leading to a steady increase in its atmospheric concentration
What 3 factors can be compared to provide insight about climate change?
When fuel emissions, atmospheric CO2 concentrations and global temperatures are compared, the following trends are revealed
What is there a strong correlation between?
There is a strong positive correlation between increasing fossil fuel emissions and rising atmospheric concentrations of CO2
How have CO2 concentrations changed? figures
Atmospheric CO2 concentrations have increased ~38% since pre-industrial times (1800: ~ 280 ppm ; 2010: ~ 380 ppm)
What concentration of CO2 emissions stayed in the air?
About 40% of CO2 emissions have remained in the atmosphere, the rest has been absorbed by carbon sinks (mainly oceans)
What does the increase in atmospheric CO2 concentration correlate with?
This increase in atmospheric carbon dioxide concentration correlates with an increase in average global temperature
Overall, what conclusion can be formed between CO2 and climate change?
While correlation does not equal causation, there is mounting evidence to suggest that CO2 emissions are linked to global temperature changes (although other factors likely also contribute)
What relation do oceans have in relation to CO2?
The oceans are a major carbon sink and absorb roughly a third of all human produced (anthropomorphic) CO2 emissions
What is CO2 solubility dependent upon?
CO2 solubility is temperature dependent (more soluble when cooler), so less CO2 will be absorbed as temperatures rise
In what form is atmospheric CO2 absorbed by the sea?
When oceans absorb atmospheric CO2, some of it will remain dissolved in a gaseous state but most will be chemically modified:
- What does CO2 combine with in the ocean and what does this form?
Carbon dioxide will combine with water to form carbonic acid, which dissociates into hydrogen ions and hydrogen carbonate
- How do H+ ions affect ocean pH as well as mineral composition of the ocean?
H+ ions will lower the ocean pH (acidification) and will also combine with free carbonate ions to form more hydrogen carbonate
- How does decreasing concentration of carbonate ions affect ocean ecosystems?
With less free carbonate ions in the water, marine organisms are less able to produce calcium carbonate (via calcification)
- What do marine organisms use CaCO3 for?
Calcium carbonate is used to form the hard exoskeleton of coral and is also present in the shells of certain molluscs
- What is the overall conclusion between CO2 concentration in oceans?
Hence increasing concentrations of dissolved carbon dioxide threatens the viability of coral reefs and certain molluscs
What does increasing atmospheric CO2 affect in relation to ocean water? name of phenomenon
Rising levels of atmospheric carbon dioxide are causing a decrease in the pH of ocean water (ocean acidification)
How has ocean pH changed over time?
Since the start of the industrial revolution ocean pH has dropped from ~8.2 to ~8.1 (roughly a 30% increase in acidity)
How is ocean pH predicted to change?
It is predicted that if current conditions continue, oceanic pH could fall to roughly 7.8 by the turn of the century (2100)
What is the decrease in ocean pH predicted to affect?
The decrease in ocean pH is predicted to threaten the survival of marine organisms that require calcium carbonate
What does an increase in H+ ions cause?
An increase in the concentration of H+ ions means there are less free carbonate ions available for calcification
How are shells and coral exoskeletons affected by decreased pH?
Shells and coral exoskeletons are also likely to begin to dissolve when ocean conditions are more acidic
WHat does increasing water acidity correlate with?
Experiments have shown that increasing water acidity correlates with the significant thinning of shells over several weeks
What organisms do not exist in regions with high levels of dissolved CO2?
Corals, sea urchins and shelled molluscs do not exist in regions with high levels of dissolved CO2 (e.g. near hydrothermal vents)
What are 3 consequences of ocean acidification?
The disappearance of coral reefs could result in a loss of shoreline protection and habitat, altering coastal ecosystems
The loss in revenue from tourism and food industries is predicted to cost economies upwards of $1 trillion by 2100
Increasing the dissolved CO2 levels in oceans would cause invasive species of algae to flourish (more photosynthesis)
What is a weak aspect of mny arguments made against climate change?
Many claims have been made regarding the impact of human activities on climate change – not all are supported by evidence
Many arguments are not backed by reliable scientific data or are made by entities with vested interests (e.g. oil companies)
What is evidence for this claim:
Climate has changed in the past and current trends merely reflect the Earth’s natural climatic cycle
Data collected from the Vostok ice core shows several changes in climate over the last 400,000 years (Figure 1)
At several points in history, global average temperatures have been warmer than those currently observed
What is a counterargument for this claim:
Climate has changed in the past and current trends merely reflect the Earth’s natural climatic cycle
Climate changes do occur naturally, but usually not as abruptly as what is seen currently
When global warming occurred abruptly in the past, it was always highly destructive to life (e.g. Permian mass extinction)
Atmospheric CO2 levels positively correlate to average global temperatures and are currently at the highest levels ever recorded
What is evidence for this claim?
Temperatures on Earth are influenced by the amount of solar radiation from the sun (more radiation = warmer temperatures)
Warmer temperatures may be caused by an increase in solar irradiance by the sun (as determined by the number of sunspots)
What is a counter-argument for this claim:
Climate change is being caused by solar activity and the effect of greenhouse gas emissions is negligible
Over the last 35 years the sun has shown a slight cooling trend, however average global temperatures have increased (Figure 2)
There is no evidence to support a correlation between solar irradiance and current global temperature trends
What is evidence for this claim?
Certain changes in climate conditions cannot be linked to greenhouse gas emissions
Global sea levels began to increase before greenhouse gas emissions significantly increased following the industrial revolution
Therefore climate changes like rising sea levels are unrelated to greenhouse gas emissions (Figure 3)
What is a counter-argument for this claim:
Certain changes in climate conditions cannot be linked to greenhouse gas emissions
The overall pattern of change in sea levels will be influenced by the period of time over which the data is collected
While sea levels did increase preceding the industrial revolution, this rise in sea levels followed a preceding period of decrease
The rate at which sea levels have risen in the past 30 years is greater than that seen in the last 200 years
What is evidence for this claim:
Variability between predicted climate change models means that such models are unreliable
Three different models of predicted climate change commissioned by the IPCC show variation of more than 5ºC (Figure 4)
Climate change models are based on assumptions and if those assumptions are false, the predictions will be incorrect
What is a counter-argument for this claim?
Variability between predicted climate change models means that such models are unreliable
The assumptions made by the different models relate to the extent of human activity predicted over the next 100 years
Model A1B predicts a continued reliance on fossil fuels while model B1 predicts a reduction in the current use of raw materials
All three models still predict an increase in average global temperatures over the next 100 years
What is evidence for this claim?
Increases in greenhouse gas concentrations in the atmosphere will not be enough to cause significant climate change
As of 2009, there were only ~39 molecules of carbon dioxide per 100,000 molecules in the atmosphere
At our current rate of CO2 emission, it will take mankind another 5 years to raise that level by 1 molecule (to 40 per 100,000)
While we may double atmospheric CO2 levels by the end of the century, doubling a small number still produces a small number
What is a counter-argument for this claim?
The reason why carbon dioxide is so important to the environment is because there is so little of it
Living things require constant internal environments (homeostasis) – small external changes can have big impacts on viability
