4.4 Climate Change
Terms in this set (12)
Carbon dioxide and water vapour are the most significant greenhouse gases
What are greenhouse gases? How are carbon dioxide and water vapour formed and removed from the atmosphere?
The Earth is kept warmer than it normally is due to retaining of heat in the atmosphere by several gases - they are known as greenhouse gases. The ones with the most significant effects are carbon dioxide and water vapour.
1) Carbon dioxide: Released into the atmosphere through aerobic respiration and combustion of biomass and fossil fuels. Removed by photosynthesis and dissolving into oceans
2) Water vapour: Released into the atmosphere by evaporation and transpiration, removed by rainfall and snow.
Other gases including methane and nitrogen oxides have less impact
Examples of other greenhouse gases? Why are nitrogen and oxygen not greenhouse gases?
There are other greenhouse gases which have the same purpose but have smaller effect:
- Methane which is produced in anaerobic environments and extraction of fossil fuels from melting ice.
- Nitrous oxides which are produced naturally by bacteria and also by vehicle exhausts.
The most abundant gases, oxygen and nitrogen are not greenhouse gases as they do not absorb long wave radiation.
The impact of a gas depends on its ability to absorb long-wave radiation as well as on its concentration in the atmosphere
2 factors determining the warming effect of a gas and give several examples?
The two factors determining the warming impact of a greenhouse gas include, how readily it absorbs long wave radiation and its concentration in the atmosphere.
Methane absorbs long wave radiation the most readily has a much lower concentration than other gases.
Concentration: The rate at which the gas is released into the atmosphere and for how long it remains there.
The warmed Earth emits longer-wave radiation
Warmed surface absorbs short wave energy and releases it at much longer wavelengths.
Longer wave radiation is reabsorbed by greenhouse gases which retains the heat in the atmosphere
What do greenhouse gases do to warm the earth.
Small portion of Short-wavelength radiation is absorbed before reaching earths surface and re-emitted as long-wavelength radiation. The short-wavelength radiation that does reach Earth is usually converted to heat.
Of the long wave radiation tat is re-emitted by the earths surface, a large portion is captured by greenhouse gases and some is emitted towards the Earth.
Correlations between global temperatures and carbon dioxide concentrations on Earth
How can the correlation be tested?
Concentration of greenhouse gas present has an effect on the global temperatures - this can be tested using carbon dioxide as its concentration has changed a lot.
Bubbles of air can be found from down below in ice and carbon dioxide concentration can be tested and compared to concentration now as well as global temperature change.
There has been a correlation between carbon dioxide concentration and global temperature.
Global temperature and climate patterns are influenced by concentrations of greenhouse gases
What influence do gloval temperatures have?
it is believed that if there is a change in greenhouse gas concentration, there will be a change in the average global temperature - this is not necessarily true because there are other factors which need to be taken into account.
Global temperature can influence...
Evaporation of water from oceans
The number of storms and wind speeds
Not all areas will become warmer with some areas have rainfall and flooding and others with droughts.
There is a correlation between rising atmospheric concentrations of carbon dioxide since the start of the industrial revolution two hundred years ago and average global temperatures
In the industrial revolution, combustion of coal oil and natural gases increased and carbon dioxide concentration increased rapidly,
There was a correlation between carbon dioxide concentration and global temperatures however other factors do have an effect so it cannot be completely certain.
Since industrial revolution, the correlation is very marked.
Recent increases in atmospheric carbon dioxide are largely due to increases in the combustion of fossilised organic matter
Shown by the industrial revolution, an increase in the combustion of coal results in very steep inclines in the atmospheric concentration of carbon dioxide.
Assessment of the claims that human activities are not causing climate change
- Scientists need to base their ideas on evidence and are expected to admit uncertainties which could make evidence seem weaker than it is
- Global climate patterns are complex and it is different to predict
- Consequences could be severe so there could be feeling of need to address the issue now
Evaluating claims that human activities are not causing climate change
* requirement of evidence to support ideas
Threats to coral reefs from increasing concentrations of dissolved carbon dioxide
Effect of carbon dioxide on marine life?
Increased release of carbon dioxide has effected the pH levels in the sea resulting in an increase in acidity.
Marine animals with calcium carbonate parts such as reef building corals need to absorb carbonate ions
Carbonate ions already low in concentration but dropping further because when carbonic acid dissociates the hydrogen ions react with the carbonate ions.
If this concentration decreases further, populations will fall. Areas of acidified water have no corals or animals that make their skeletons from calcium carbonate.
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