C6.3 Interpreting and interacting with Earth Systems

Question 1

Explain how the atmosphere is thought to have originally formed

Answer 1

• Earth is 4.54 billion years old. There was a great deal of volcanic activity during its early years which released substances, forming the early atmosphere
• No-one was around to record events as they happened, so it’s difficult to be certain that this theory is correct
• Volcanoes released huge volumes of water vapour and carbon dioxide, and as the earth cooled, the water vapour condensed to form oceans, leaving an atmosphere of mostly carbon dioxide
• it probably contained small amounts of other gases such as ammonia and methane, but little or no oxygen

Question 2

Describe how it is thought an oxygen-rich atmosphere developed over time

Answer 2

• Theories suggest that when plants and algae appeared, photosynthesis reduced the amount of carbon dioxide in the atmosphere and also released oxygen (absorbed CO2 and released O2)
• at first, the oxygen reacted with metals in rocks to produce metal oxides
• later, as most of the metals became oxidised, free oxygen began to accumulate in the atmosphere and eventually there is the oxygen-rich atmosphere today that has developed

Question 3

Describe the composition of the atmosphere today

Answer 3

Nitrogen, oxygen and argon form 99.9% of Earth’s atmosphere today
- smaller % of many other gases, including carbon dioxide and water vapour

Question 4

Describe the major source of carbon monoxide in the atmosphere and explain the problems caused by increased amounts of it

Answer 4

• produced during incomplete combustion of fuels containing carbon
• can happen when coal, wood, natural gas are burned in poor supply of air and in vehicle engines
• toxic gas, colourless, no taste or smell
• when breathed in, CO attaches to haemoglobin protein in RBCs, reducing amount of oxygen that bloodstream can carry
• CO poisoning causes drowsiness, difficulty breathing, and even death
• many homes have CO detectors

Question 5

Describe the major source of particulates in the atmosphere and explain the problems caused by increased amounts of it

Answer 5

• small particles produced in industrial processes such as metal extraction
• like CO, they are also produced during incomplete combustion and in vehicle engines
• smallest particulates settle deep in the lungs when breathed in, causing diseases such as bronchitis and other breathing problems, and increasing chance of heart disease

Question 6

Describe the major source of acidic oxides like Sulfur dioxide and oxides or nitrogen in the atmosphere and explain the problems caused by increased amounts of it

Answer 6

• N and O, the main gases in air, don’t normally react together
• but they do react at high temps in vehicle engines, forming nitrogen monoxide (NO)
• NO is then oxidised in sir to for, NO2 - nitrogen dioxide
• These oxides of nitrogen are jointly called NOx
• NO2 (dioxide) dissolves in the moisture in clouds, forming an acid is solution, which eventually falls as acid rain
• acid rain erodes stonework + corrodes metal, and can kill trees and living things in rivers and lakes
• Fossil fuels naturally contain small amounts of sulfur compounds
• these impurities form sulfur dioxide when the fuel is burnt
• SO2 also causes acid rain, and it can cause breathing difficulties

Question 7

Describe the greenhouse effect in terms of the interaction of radiation with matter within the atmosphere

Answer 7

1- Energy transferred by radiation from Sun reaches Earth’s surface
2- Radiation warms up Earth’s surface
3- Infrared radiation is emitted by Earth’s surface. Some goes directly into space. Some is absorbed by greenhouse gas (like CO2 and CH4) molecules in the atmosphere.
4- Greenhouse gas molecules emit infrared radiation in all direction, warming Earth’s surface and atmosphere.

• the greenhouse effect keeps Earth and its atmosphere warm enough for living things to exist

Question 8

Describe the potential effects of increased levels of carbon dioxide and methane on the Earth’s climate

Answer 8

• CO2 is released into atmosphere by combustion of fossil fuels
• Methane is released into atmosphere from rice paddy fields, cattle, landfill waste sites and use of natural gas
• release of additional greenhouse gases by human (anthropogenic) activities has the potential to cause an enhanced greenhouse effect, increasing the temp of the Earth’s atmosphere
• this global warming leads to melting ice caps and rising sea levels, and to climate change
• climate change brings altered weather patterns, causing flooding, and problems with farming and disease control

Question 9

Evaluate the evidence for additional (human activity) causes of climate change and describe the uncertainties in the evidence base

Answer 9

Data comparing the change in global temps with change in carbon dioxide levels show that as the carbon dioxide levels increase, so do the global temperatures over the years.
Atmospheric CO2 concentration had increased as the consumption of fossil fuels has increased
- The IPCC (intergovernmental panel on climate change) has considered the scientific evidence for global warming and climate change, and write in one of their conclusions that it’s extremely likely that human influence was the main cause of global warming between 1951 and 2010.
- they say ‘extremely likely’ not as they’re unsure, but as the Earth and it’s atmosphere is a very large, complex system, so scientists cannot carry out a controlled fair test in the normal way
- they can make predictions based on observations, measurements and computer models but the actual outcome will only be revealed in the future.