Global warming mob," "poppycock" and "scam" are words recently used by letter writers to The Bee to put down people who have evaluated scientific evidence and concluded that global climate change is a matter of concern. Since we all share the same planet, it is important that we all understand the potential consequences of our lifestyles. The evidence is strong and growing every day that human actions will adversely affect many forms of life on Earth.
Recently, the writer of the letter "Distracted from real environmental issues" (April 30) stated correctly that water vapor is the No. 1 greenhouse gas. Fossil fuels combustion does produce predominantly water and carbon dioxide, but the amount of water produced is small compared with the amount of water already in the atmosphere. There is very little naturally occurring carbon dioxide in Earth's atmosphere. Carbon dioxide ranks only fourth in dry air, making up 0.038 percent of the atmosphere. Carbon dioxide was about 0.028 percent of the atmosphere at the beginning of the Industrial Revolution. The increase from 0.028 percent to 0.038 percent can be directly attributed to fossil-fuel combustion.
The temperature of the Earth is more difficult to measure, but the best evidence available indicates the Earth has warmed about 1.3 degrees Fahrenheit in the last 100 years. The writer also cited that over the last several hundred thousand years, there is some evidence that Earth's temperature spikes have preceded and possibly caused the observed carbon dioxide spikes. As oceans warm, carbon dioxide is expelled from them. Unfortunately, in the current situation the cause and effect are probably reversed. Human activity is definitely increasing the carbon dioxide content, but this is where the science becomes very complex.
The best models scientists have reveal very close correlations of carbon dioxide with temperature increases over the last several decades. The models project disastrous effects from increasing temperatures if carbon dioxide concentrations continue to increase. The 90 percent probability statements of the 2007 Intergovernmental Panel on Climate Change report are weighty scientific statements that should not be ignored.
The question is whether we can afford to gamble with the future of Earth's life-support systems.
Everything we do to develop alternate energy sources to combat possible global warming, we should be doing anyway because of other very serious negative effects of fossil fuels (oil spills, air pollution, wars, etc.).
Some suggest we should wait to act until we know for sure if global warming caused by humans is occurring. The problem is that actions to level or reverse the effects of fossil fuel use require many decades to implement. In other words, definitive evidence might not be produced until it is too late to avert widespread and serious damage.
We need to learn from the ozone depletion problem that was predicted by scientists in the early 1970s. Fortunately, in that case, the United States and later the world listened to scientists and took action. Today, evidence indicates we have minimized the serious effects that would have resulted had we continued to use Freon.
Global warming models indicate we will have increasingly serious problems if we do not act to decrease our dependence on fossil fuels. Neglect is not an intelligent response to our climate situation.
Murov is an emeritus professor of chemistry at Modesto Junior College.