Topic 4.4 Climate Change
LIST the greenhouse gases, and OUTLINE their impact on the greenhouse effect.
→ Greenhouse gases include: --→ Carbon dioxide. --→ Water vapour. --→ Methane. --→ Nitrogen oxides. → All greenhouse gases can absorb longer wave radiation but not with the same ability. → The impact of a greenhouse gas depends on how able it is to absorb longer wave radiation and on its concentration. → Although methane absorbs longer wave radiation better than carbon dioxide, it is present at much lower concentrations. → Highest impact greenhouse gases are carbon dioxide and water vapor. → Lower impact greenhouse gases are methane and nitrogen oxides. → Loss of the ozone layer is not a factor in the greenhouse effect.
OUTLINE the threat to coral reefs from increasing concentrations of dissolved carbon dioxide.
→ Increased atmospheric carbon dioxide concentration in the atmosphere, has led to an increase in the amount of carbon dioxide dissolved in the ocean. → This has caused the ocean to become less alkali since carbon dioxide reacts with water to form carbonic acid (which dissociates). → Hydrogen ions react with carbonate ions and reduce carbonate ion concentrations. → Carbonate ions are required by coral to synthesize calcium carbonate for their skeletons. → Coral will grow more slowly. → Hydrogen ions can also react with the calcium carbonate skeletons of the corals and cause it to break down. → Any future increases in carbon dioxide concentration, will increase the threat to coral reefs.
OUTLINE the greenhouse effect.
→ Short wave radiation from the sun reaches the earth. → Some is reflected by the earth's atmosphere. → Most of it gets through the earth's atmosphere and is absorbed by the earth's surface. → The earth's surface warms up and emits longer wave infrared radiation (heat). → Some longer wave radiation escapes into space. → Most of the longer wave radiation is absorbed by greenhouse gases in the atmosphere. → The greenhouse gases scatter the longer wave radiation. → This traps heat in the atmosphere.
OUTLINE the influence of greenhouse gases on global temperatures and climate patterns.
→ The greenhouse effect is a natural phenomenon and is essential for life on earth. → If the greenhouse effect did not exist, the average temperature on earth would be -17C (that's below freezing). → The average temperature of earth is much higher than this so greenhouse gases must influence global temperatures. → It is expected that any further increase in the concentration of greenhouse gases, will increase the average temperature of the earth. → Increasing global temperature will also impact climate patterns, creating extreme weather. --→ Warmer sea temperatures will increase the strength of hurricanes. In recent years, there has already been an increase in the number of strong hurricanes. --→ Warmer temperatures can influence rainfall patterns, causing heavier rainfall in some areas, leading to flooding and drought in other areas.
Some people still argue that human activities are not causing climate change. EVALUATE their claims.
→ There is no debate that the greenhouse effect occurs. → However, some people argue that greenhouse gas emissions caused by human actions (like burning fossil fuels) are not responsible for recent climate changes. → They argue that recent warming of the earth is due to natural processes, such as fluctuations in the activity of the sun and ocean currents. → They claim that the model suggesting climate change is due to human actions is based on questionable data. → However, the vast majority of scientists do accept the data (from multiple, independent studies) linking the increased temperatures with the increasing greenhouse gas levels.
