Scientists study how the concentration of carbon dioxide in the atmosphere and the mean global temperature have changed since the 1850s.
The table shows mean values for six decades.
| Decade | Mean concentration of carbon dioxide (ppm) | Mean global temperature compared with the 1850–1900 average (°C) | How the carbon dioxide value was found |
|---|---|---|---|
| 1850s | 285 | 0.0 | air bubbles trapped in Antarctic ice |
| 1900s | 297 | −0.1 | air bubbles trapped in Antarctic ice |
| 1950s | 313 | +0.3 | air bubbles trapped in Antarctic ice |
| 1980s | 346 | +0.4 | direct measurement of air |
| 2000s | 379 | +0.8 | direct measurement of air |
| 2010s | 400 | +1.0 | direct measurement of air |
Temperatures before about 1950 are calculated from fewer measuring stations and ships, and large areas of the Earth were not measured.
From the 1950s to the 1970s, burning coal released large amounts of sulfur dioxide and particulates. These reflect some sunlight away from the Earth.
Calculate the percentage increase in the concentration of carbon dioxide from the 1850s to the 2010s.
Give your answer to 2 significant figures.
Evaluate the evidence in the table that human activity is causing climate change.
Describe the uncertainties in the evidence.
Describe two potential effects of a further increase in the concentration of carbon dioxide and methane in the atmosphere.
51 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.