The concentration of carbon dioxide (CO2\text{CO}_2CO2) in the atmosphere has been rising steadily for decades. Many scientists conclude that this rise is a primary driver of increasing global air temperatures. The table below shows measurements of atmospheric CO2\text{CO}_2CO2 concentration (in parts per million, ppm) and the global average air temperature change (in ∘C^\circ\text{C}∘C, relative to a historical baseline) recorded every ten years from 1965 to 2015. | Year | Average CO2\text{CO}_2CO2 concentration (ppm) | Global average temperature change (∘C^\circ\text{C}∘C) | | :--- | :---: | :---: | | 1965 | 320 | −0.10-0.10−0.10 | | 1975 | 331 | −0.05-0.05−0.05 | | 1985 | 346 | +0.12+0.12+0.12 | | 1995 | 361 | +0.28+0.28+0.28 | | 2005 | 380 | +0.48+0.48+0.48 | | 2015 | 401 | +0.63+0.63+0.63 |
Using the data in the table: (i) Describe the overall trend in atmospheric CO2\text{CO}_2CO2 concentration from 1965 to 2015. (ii) Describe the overall trend in global average temperature change from 1965 to 2015.
Explain how an increase in the concentration of carbon dioxide in the atmosphere causes an increase in global air temperature.
Some critics argue that because global temperatures fluctuate from year to year, carbon dioxide is not causing global warming. Evaluate this objection by using the table's data and explaining why a long-term trend is more scientifically valid than single-year fluctuations.
(i) State one biological process that decreases carbon dioxide concentration in the atmosphere. (ii) Give two potential negative consequences of an increase in global air temperature on ecosystems or living organisms.