A recent letter on climate change misleads by taking items out of context and ignoring contrary evidence.
It claims that: (a) CO2 is not a pollutant but is necessary for life by forming O2; (b) water vapor is the major greenhouse gas, but we waste our efforts studying a minor gas like CO2, which is actually good for the planet; and (c) the National Academy of Sciences reported that it is impossible to accurately predict future global temperatures.
All these conclusions are erroneous. Here's why:
Of course CO2 is necessary for O2 formation, but photosynthesis utilizes only a small fraction of the CO2 in the air. Increasing CO2 levels does not result in higher O2 levels in the air. Rather, increased CO2 levels warm the earth by trapping heat on the Earth's surface.
Water vapor is indeed a major greenhouse gas. However, water vapor remains in the air for only about 10 days, compared to CO2, which remains for hundreds of years thus exerting a greater effect on global warming.
The NAS report states that, although we cannot exactly predict future earth temperature, unquestionably Earth's temperature continues to rise. What we cannot predict is the exact rate of the temperature increase. This is determined by human activity, largely fossil fuel combustion and deforestation.
In conclusion, one must always remember to analyze reports carefully and completely, and not selectively cite misleading and obfuscating points.
Allan M. Lefer