D4.3 Climate change (Ecosystems): Practice Questions

Which of the following processes is the primary driver of the enhanced greenhouse effect leading to contemporary climate change?

Which sequence of events correctly describes the physical mechanism responsible for the enhanced greenhouse effect?

Which mechanism explains why ocean warming contributes directly to rising global sea levels, independently of terrestrial ice sheet melting?

The greenhouse effect is a natural process, but human activities have led to an enhanced effect. Which statement correctly describes the mechanism by which greenhouse gases contribute to global warming?

The melting of permafrost in Arctic regions releases large amounts of methane, a potent greenhouse gas. This additional methane then contributes to further global warming, which in turn accelerates the melting of more permafrost. This describes an example of a:

The enhanced greenhouse effect is caused by altering atmospheric gas concentrations and radiation balance.

a) Outline the physical mechanism of the natural greenhouse effect, explaining why outgoing radiation from Earth is absorbed by greenhouse gases while incoming solar radiation is not.
b) State two greenhouse gases other than carbon dioxide, and identify one major anthropogenic source for each.
c) Explain why methane has a significantly higher global warming potential ( ext{GWP}) than carbon dioxide over a 20-year timescale, but carbon dioxide remains the primary long-term driver of anthropogenic climate change.
d) Describe one feedback mechanism by which rising global temperatures accelerate the release of methane into the atmosphere.

Anthropogenic carbon dioxide emissions are driving significant physical and chemical changes in marine environments.

a) Describe the chemical mechanism by which elevated atmospheric \(\text{CO}_2\) leads to ocean acidification, including the formation of hydrogen ions (\(\text{H}^+\)).
b) Explain why ocean acidification reduces the availability of carbonate ions (\(\text{CO}_3^{2-}\)) needed by calcifying organisms, such as reef-building corals and molluscs.
c) State the chemical equation for the calcification reaction forming calcium carbonate, and describe the physiological consequence for coral reefs when the saturation state of calcium carbonate decreases.
d) Suggest one secondary ecological consequence of extensive coral reef degradation on coastal marine biodiversity.