Grade 12 Geography unit 2: Climate change

Weather is the state of the atmosphere over a short period, while climate is its average over a long one, conventionally 30 years. Option A reverses the two, which is the mistake that also produces the argument that one cold week disproves climate change.

Without the natural greenhouse effect the earth would average about -18 degrees Celsius rather than about 15, and life as we know it could not exist. What is damaging is the enhanced effect from extra emissions. Ozone depletion is a separate problem about ultraviolet radiation, so option D confuses two different issues.

Methane comes from livestock digestion, flooded rice fields and decomposing waste. It matters greatly for Ethiopia given the size of the national herd, because methane traps far more heat per molecule than carbon dioxide. Nitrous oxide is associated with fertilisers instead.

Adaptation means coping with changes that are already happening. A terrace does not lower anyone's emissions; it protects the farm from rainfall that has already changed. Mitigation attacks the cause, which is what planting trees or installing solar panels does.

Water expands as it warms, and that thermal expansion contributes roughly as much as melting glaciers and ice sheets. Melting sea ice that is already floating adds almost nothing to sea level, which is why option B fails.

The Paris Agreement of 2015 asks every country to pledge cuts, unlike Kyoto in 1997 which bound only developed countries. The Montreal Protocol dealt with ozone depleting substances, and the Rio Earth Summit of 1992 produced the framework convention that the later agreements sit under.

Most Ethiopian farming depends directly on rainfall rather than irrigation, so any change in the timing or amount of the kiremt rains passes straight through to the harvest. Ethiopia is in fact a very low emitter, which is the basis of its argument for climate finance under the principle of common but differentiated responsibilities.

Replacing fossil fuel generation reduces emissions, so it attacks the cause. The other three all help people cope with changes that have already arrived, which makes them adaptation.

The CRGE, launched in 2011, aims to reach middle income status without raising net emissions, and rests on those four pillars. The Green Legacy tree planting campaign sits under the forestry pillar, and the expansion of hydro, geothermal and wind sits under power.

The mosquito that carries malaria was limited by the cool highland temperatures. As those areas warm, the mosquito's range moves upslope into populations with little previous exposure. Sea level rise is irrelevant to a landlocked country.