Climate Change and Carbon Sequestration Questions and Answers

Answer: C

The agreed reduction was 5.2 percent.

Under the Kyoto Protocol of 1997, the industrialised countries listed in Annex B agreed to cut their combined greenhouse gas emissions by an average of about 5.2 per cent below 1990 levels during the first commitment period, 2008 to 2012.

3.2, 4.2 and 6.2 per cent are close figures used as distractors. Developing countries such as India had no binding targets under the Protocol, in line with the principle of common but differentiated responsibilities.

Answer: C

The greenhouse gas present in the largest concentration among those listed is carbon dioxide.

Carbon dioxide is present at about 420 parts per million, far more than nitrous oxide (about 0.34 ppm) or the chlorofluorocarbons and hydrofluorocarbons, which are measured in parts per trillion. (Water vapour is more abundant still, but it is not among the options.)

Concentration is different from warming power per molecule: CFCs and HFCs are thousands of times more potent than CO₂ but present in tiny amounts.

Answer: C

The main greenhouse gas among the options is carbon dioxide.

Carbon dioxide is the most important greenhouse gas released by human activity, from burning fossil fuels and clearing forests, and it accounts for the largest share of the additional warming since industrialisation. Its concentration has risen from about 280 ppm before 1750 to over 420 ppm.

Nitrogen makes up most of the atmosphere but does not absorb infrared radiation, so it is not a greenhouse gas. Chlorine is not a greenhouse gas either, and ozone is a greenhouse gas but a minor one compared with CO₂.