GLOBAL WARMING: WHO DO YOU BELIEVE?

After months of being barraged with political spin and various scares of one type or another, we are presented with one last spin on the notion of Global Warming. Professor J. tells us (DVC Forum 11/20) that polls indicate only 15-20 % of atmospheric scientists are convinced that global warming is underway, and in another survey only 19% believe that global warming is a consequence of human activity. He offers that increased CO₂. may be benefical to plant life, and views the application of computer modelling as unverifiable with possible disastrous implications. Finally he suggests purging the "scare" by dumping it into "the honey bucket of history".

Historically there has been a fluctuation of about 2 ^oC in average global atmospheric temperature which makes conclusions on what is happening and what may happen to global temperatures arguable. However, contrary to Jim's polls, the scientific community represented by 300 leading earth scientists on the United Nations Intergovernmental Panel on Climate Change have concluded that average global temperature has increased between 0.3 to 0.6 ^oC in the last 100 years and will rise 1.5 to 4.5 ^oC by the middle of the next century. This increase will markedly change the earth's climate.

The lower part of our atmosphere, the troposphere, is comprised primarily t99%) of 2 gases which we breathe: nitrogen (78%) and oxygen (21%). The remaining 1% of air contains several trace gasos including carbon dioxide (CO₂,), methane (CH₄.) and water. Carbon dioxide is one of the most important trace gasea. It is produced as a product of combustion, burning, which results from combination with oxygen. This can be biological such as burning "calories" in our bodies or physical such as forest fires and the combustion of gasoline in our automobiles. Since the year 1800, amounts of CO₂, and CH₄. have increased dramatically on a geochemical time scale versus pre-industrial levels, 25% and 50% respectively. For every gallon of gasoline we consume, over 20 pounds of CO₂, is placed into the environment! An average commuter produces over 100 pounds of CO₂ per week. Over 3 Billion tons of CO₂. end up in the atmosphere each year from the burning of fossil fuels: gas, oil and coal. Another 2 Billion tons are actually produced but are unaccounted for.

Different materials absorb different quantities of heat. For example, water has the capacity to absorb about 20 times more heat than the metal silver. The air in our atmosphere absorbs heat and traps it much like a greenhouse. This is normal. Without air, a large amount of the heat produced from solar radiation would be lost to space and the earth's temperature would drop significantly. Wlth the mantle of air, some heat is trapped which warms our planet. The problem is that "greenhouse gases" such as CO₂. absorb more heat than nitrogen and oxygen and this circumstantial evidence has led to their implication in global warming. Also, recent studies indicate that elevated CO₂, levels do not increase biomass in tropical plants. But, it may be increasing the biomass of oceanic plants, phytoplankton (algae and alike). This may explain the fate of the unaccounted 2 Billion tons of carbon. The increased number of cases of shell fish poisoning may also be a result of this increase since shell fish filter feed and concentrate algal produced neurotoxins, such as saxitoxin. A millionth of an ounce of saxitoxin can fatally paralyze a human.

What this means for the future is problematic, and as J. has demonstrated so well, it can be spun many different ways. Nevertheless, supercomputing models provide perspectives that would otherwise be unavailable. Much as Copernicus's and Galileo's unique intellectual vision in the 16th century provided a new perspective of the solar system and Binstein's of the atom in the 20th century. The Vatican has just dipped into the honey bucket of history, finally acknowledging after some 300 years that Copernicus and Galileo were correct: ...the sun...not the earth is the center of our solar system. For his heresy Galileo lost his reputation but kept his life. Copernicus was not so fortunate.

If only some of the global perspectives from the various climate models prove to be correct, future generations (like Copernicus) may not have the luxury to correct the mistakes of the past. It is a risk not worth taking. Only prudence, open-mindedness and willingness to change can guarantee a secure legacy for our successors. How many gallons of gasoline do you burn each year? How much fossil fuel does PG&B burn at the Antioch plant to light and heat our offices, classrooms and homes? How much CO₂, does this equate to? In the vernacular of our students: HellaLot! They certainly believe it's a problem even though some experts may not.