C13 : 13.3 - Greenhouse gases

Question 1

what are the main greenhouse gases

Answer 1

CO2, water vapour, methane

Question 2

what do greenhouse gases in the atm. do

Answer 2

maintain temps high enough to support life on earth.

Question 3

what do the greenhouse gases absorb

Answer 3

absorb energy radiated from Earth’s surface

Question 4

describe the greenhouse gas effect in terms of short wave and long wave radiation interacting w matter

Answer 4

• The greenhouse gases let short-wavelength EM radiation emitted by the Sun to pass through
• The Earth’s surface absorbs most of this radiation and warms up
• But some radiation is re-emitted from the surface of the Earth as IR radiation - which has a longer wavelength - as the Earth cools down
• Some of this IR radiation goes into space
• And some is absorbed by the greenhouse gases
• This warms the atmosphere => hence leading to energy being radiated off the surface trapped in that atm and the Earth becomes hotter

Question 5

what is the enhanced greenhouse effect

Answer 5

increase in co2 and methane => causing excessive heat to be trapped => cause of global warming

Question 6

difference between greenhouse and enhanced greenhouse effect

Answer 6

• Greenhouse effect ensures the Earth’s temp is around 15 degrees, otherwise would swing between extreme hot and cold
• The enhanced greenhouse effect, due to an increase in greenhouse gas concentrations, most scientists believe, is leading to global warming.

Question 7

examples of human activities that increase co2 conc in atm

Answer 7

• Combustion of fossil fuels
• Deforestation
• Burning and destruction of peat bogs
• Respiration of plants and animals
• thermal decomposition of carbonate rocks and the effect of acids on carbonates
• as temp increases, co2 gets less and less soluble in water

Question 8

examples of human activities that increase methane conc in atm

Answer 8

• Increased farming => increased methane due to digestive processes
• decomposition of vegetation,
• bacterial action in swamps and in rice paddy fields

Question 9

how is the the evidence for the effects of CO2 on global temperature convincing

Answer 9

• by analysis of the percentage of CO2 in the atmosphere
• and changes in temperature over several hundred years

Question 10

what is done by the evidence collected by scientists regarding global climate change and why

Answer 10

• evidence is peer-reviewed
• to make sure that the results are valid and they are confident with the conclusions made

Question 11

what does the peer-reviewed evidence of co2 levels and temp changes show

Answer 11

• shows a clear correlation between the percentage of CO2 in the atmosphere and the changes in temperature
• This has led many scientists to agree that human activities will cause the temperature of the Earth’s atmosphere to increase at the surface and that this will result in global climate change.

Question 12

what does advances in science and technology mean regarding the current levels of CO2 and global temperatures

Answer 12

• current levels of CO2 and global temperatures can be determined with a high degree of accuracy

Question 13

why is historical data less accurate

Answer 13

• due to the lack of accurate instrumentation and methods
• Fewer locations would also have been measured due to the lack of satellites and transport

Question 14

what are some methods to estimate past climate conditions and are they precise?

Answer 14

• analysis of the fossil record and tree rings
• Analysis of gas bubbles trapped in ice from hundreds of thousands of years ago
• not as precise as modern day techniques nor do they provide data which is representative on a global scale

Question 15

why is it difficult to model global climate change and what has this led to

Answer 15

• the complexity of the Earth’s climate and contributing factors and variables make it diff to produce a working model that clearly shows the link between global warming and greenhouse gases
• this has led to simplified models, and speculation and opinions presented in the media that may be based on only parts of the evidence and which may be biased (e.g. some scientists doubting human activity and climate change )

Question 16

what is important to carry out to dispel myths and misinformation about climate change and why?

Answer 16

• peer review of research results as well as communication to a wide range of audiences is carried out
• so that other scientists can check the results and interpretation, and repeat the experiments for themselves.

Question 17

what should you consider When evaluating the quality of evidence on an issue like global warming

Answer 17