IB DP Biology Topic 4: Ecology : 4.4 Climate change Question Bank HL Paper 1

Question

What contributes to rising atmospheric concentrations of carbon dioxide and increases in average global temperature?

A. An increase in the shorter wavelength radiation emitted by Earth
B. An increase in longer wavelength radiation emitted by Earth
C. An increase in the combustion of fossilized organic matter
D. The depletion of ozone in the stratosphere

▶️Answer/Explanation

Markscheme

Ans: C

An increase in the combustion of fossilized organic matter, such as coal, oil, and natural gas, contributes to rising atmospheric concentrations of carbon dioxide and increases in average global temperature in several ways.

When fossil fuels are burned, the carbon that has been stored in them for millions of years is released into the atmosphere as $\text{CO}_{2}$. This additional $\text{CO}_{2}$, which would otherwise have remained underground, adds to the amount of greenhouse gases in the atmosphere and contributes to the enhanced greenhouse effect. This leads to an increase in global temperatures, as the greenhouse gases trap more heat in the Earth’s atmosphere.

The increase in atmospheric $\text{CO}_{2}$ concentrations also has other effects, such as ocean acidification. When $\text{CO}_{2}$ dissolves in seawater, it reacts to form carbonic acid, which can lower the pH of the ocean and have negative impacts on marine ecosystems.

The burning of fossil fuels also releases other pollutants, such as sulfur dioxide and nitrogen oxides, which can have negative impacts on air quality and human health.

Question

Human activity leading to the emission of greenhouse gases may be a cause of global warming.
According to the precautionary principle, what should be done about greenhouse gas emission?
A. Analyse historical records from monitoring stations to see the trends in carbon dioxide emissions
B. Obtain more evidence by carrying out research on greenhouse gas emission
C. Take measures to lower greenhouse gas emission without further evidence
D. Develop strategies for coping with higher global temperatures

▶️Answer/Explanation

Markscheme

C

In the case of greenhouse gas emissions, there is scientific consensus that human activity is contributing to global warming, and that this warming has the potential to cause significant environmental and social impacts. Therefore, the precautionary principle suggests that action should be taken to reduce greenhouse gas emissions in order to mitigate these risks. This could involve a range of actions, such as reducing fossil fuel use, increasing energy efficiency, promoting renewable energy, and implementing policies to encourage emissions reductions. By taking action to reduce greenhouse gas emissions, we can help to prevent or mitigate the potential harms associated with global warming.

Question

What is the best definition of the greenhouse effect in the Earth’s atmosphere?
A. A naturally occurring effect by which shorter wavelength radiation is trapped
B. A naturally occurring effect by which longer wavelength radiation is trapped
C. An effect of pollution by which shorter wavelength radiation is trapped
D. An effect of pollution by which longer wavelength radiation is trapped

▶️Answer/Explanation

Markscheme

B

An effect in which a naturally occurring effect by which longer wavelength radiation is trapped is the greenhouse effect. The greenhouse effect is a naturally occurring process in which certain gases in the Earth’s atmosphere, such as carbon dioxide ($\text{CO}_{2}$), water vapor, and methane, trap some of the sun’s energy that has been absorbed by the Earth’s surface. These gases absorb and re-emit some of the energy, which causes some of the heat to be trapped in the atmosphere, rather than being radiated back into space. This helps to keep the Earth’s temperature within a range that is suitable for life.

Question

The table shows the monthly CO2 concentrations in mg L–1 taken at two monitoring stations.

What is directly indicated by the data?
A. CO2 concentration in the atmosphere varies from place to place.
B. Cape Grim is less affected by global warming than Mauna Loa.
C. CO2 creates a greenhouse effect at both locations.
D. The standard deviation for Cape Grim is higher than standard deviation for Mauna Loa.

▶️Answer/Explanation

Markscheme

A

The concentration of $\text{CO}_{2}$ in the atmosphere varies from place to place due to a variety of factors, including natural processes and human activities.

Natural processes that influence $\text{CO}_{2}$ concentrations include photosynthesis, respiration, and the exchange of $\text{CO}_{2}$ between the atmosphere and oceans. Photosynthesis removes $\text{CO}_{2}$ from the atmosphere, while respiration and decomposition release $\text{CO}_{2}$ back into the atmosphere. The exchange of \textup{CO}_{2} between the atmosphere and oceans is influenced by factors such as ocean temperature, salinity, and circulation patterns.

Human activities, such as burning fossil fuels and deforestation, have also contributed to the increase in atmospheric $\text{CO}_{2}$ concentrations over the past century. Burning fossil fuels releases \textup{CO}_{2} that has been stored underground for millions of years, while deforestation reduces the number of trees that can absorb $ \text{CO}_{2}$ through photosynthesis.

The concentration of $\text{CO}_{2}$ in the atmosphere is also influenced by local factors, such as the proximity to sources of $\text{CO}_{2}$ emissions, the presence of vegetation, and weather patterns. For example, urban areas may have higher $\text{CO}_{2}$ concentrations than rural areas due to the concentration of human activities and emissions.

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