1. Is global warming really occurring? If so, what causes it?
Between 1860 and 1990, the earth's average temperature increased by 1.5
F degrees or 0.83 Celsius degrees. The increase was by no means linear. For about
70 years, the average oscillated with no overall change. Then there was a warming
period from 1930 to 1960, followed by two cooler decades. After a cooling period
brought about by the Pinatubo eruption, 1993 was another abnormally hot year. Global land and sea records show that 1997 was the warmest year on record.
The warmth continued a trend with 9 of the
warmest years on record occurring in the
past 11 years. [ National
Climatic Data Center (NCDC).]
What makes a stronger connection between CO2 levels and temperature is the historical record. By analyzing ice that has been around for a half million years we can measure CO2 levels of the distant past. In addition O-18 to O-16 isotope ratios or H-2 to H-1 ratios give us an idea of temperature. The data from Antarctica reveals that temperatures and CO2 levels vary hand in hand.
While this has been going on, the amount of carbon dioxide in the atmosphere increased from 274 ppm in 1860 to about 363 ppm in 1996(a 32% increase).* Meanwhile if you also consider the increase in methane gas (CH4) in the atmosphere, we now have the equivalent of 403 ppm of CO2, an increase of 47%. Both these gases are transparent to visible wavelengths of light but absorb infrared. Thus, they allow the earth to be warmed by sunlight in the day but interfere with the cooling of the earth at night.
In essence then, we have two sets of numbers that increased in unison over the same time frame, and given the chemical properties of one set, it is plausible that they are responsible for the observed increase in temperature.
*For complete data, check the Mauna Loa site.
Questions Regarding Data:
2. Is it true that there would be no life on earth without any CO2?
Yes. Without any CO2, the earth would be a much colder planet, about 18 Celsius degrees cooler then its present state. Increases in CO2 over many centuries or millennia have taken us out of ice ages, but the recent surge is occurring over a much shorter period. Keep in mind that the planet Venus has a runaway warming effect which turns its surface into a furnace in spite of the fact that its sulfuric acid clouds reflect most of the sun's energy back into space. The earth, of course, will not become another Venus because of its distance from the sun, yet it could still face some serious consequences.
3. How then can global warming harm us?
A continued increase in global temperatures could partially melt polar icecaps*,
flooding coastal areas, affecting big North American cities and important low-lying agricultural
areas in India and China.
* Note, however, that if a large mass of ice consists of ocean water, such as the one in the Arctic, it already displaces a large volume of water. Upon potentially melting it would simply replace that volume and would not raise ocean levels. If on the other hand continental ice ( i.e. Antarctica) is warmed to the point that it breaks off and slides into the ocean, then that floating mass of ice immediately raises the level of the ocean, even before melting.
There could also be a major disruptance of climate inland, rendering wheat-growing areas hot and arid.
4. Why have we had an increase in gases that lead to global warming ?
Since the industrial revolution our economy has been driven by carbon- containing fuels: coal, petroleum and natural gas. When oxidized, these substances all produce CO2. At the same time, the number of cattle and rice paddies have increased, which accounts for the increase in methane. Other warming gases introduced this century include CFC's (used in refrigerants and air conditioners) and nitrous oxide, formed from the concentration of fertilizer and animal waste.
5. How can the problem be alleviated?We have to get a little more daring with new technological developments. Practical electric cars could be put on the market in the next five years if we wanted them badly enough. (see Scientific American: November 1996 p54). Conservation practices i.e. better windows and electric lights could also greatly diminish the amount of fuel burnt needlessly. Somehow most people have equated progress with learning how to use word processors. Instead there is technology out there that can really make the world a better place. But it is not in the limelight at the present!
Created: April/7/96; Updated: March 24, 2006