A climate model estimates the effects of three global plans to limit climate change by 2100.
| Plan | Greenhouse gas | Predicted reduction in concentration (parts per billion) | Warming effect of one molecule compared with one molecule of carbon dioxide |
|---|---|---|---|
| K: replace fossil fuel heating with renewable energy | Carbon dioxide | 7 000 | 1 |
| L: reduce cattle numbers | Methane | 320 | 25 |
| M: plant more trees | Carbon dioxide | 5 000 | 1 |
Which plan is predicted to prevent the most warming, and why?
Plan M, because trees remove carbon dioxide that has already been released into the air.
Plan K, because it also cuts sulfur dioxide emissions, which add to acid rain.
Plan L, because 320 × 25 gives a larger value than the reduction for Plan K or Plan M.
Plan K, because it gives the largest fall in the concentration of a greenhouse gas.
109 exam-style questions on OCR GCSE Chemistry 6.3 Interpreting and interacting with earth systems, covering 6.3.1 Formation and evolution of the atmosphere, 6.3.2 The greenhouse effect and climate change, 6.3.3 Sources and problems of atmospheric pollutants, and 6.3.4 Producing potable water. Each one has a worked solution and a mark scheme showing where the marks go.