Since it is ridiculously hot outside and I do not have air conditioning in my apartment I am staying late at work. What follows is my understanding of how the greenhouse effect works and my intuitive thinking on what implications it has for weather over all.

CO2 concentrations are increasing as a result of human use of fossil fuels. Over the course of the last billion years, plant life has extracted carbon from carbon dioxide in the atmosphere and used it to create large molecules which do not return to the atmosphere and after a long time form coal and oil deposits. Coal deposits were mainly formed from ancient forests. Not sure what creates the oil or natural gas deposits. In the last few centuries we have been rapidly taking all of that CO2 and returning it to the atmosphere.

There is no question that the CO2 content of the atmosphere has increased over the course of the last century. The last I recall CO2 concentrations had increased by at least 25%. CO2 is still only present in the atmosphere in trace amounts but 25% seems pretty dramatic to me.

There also is no question that when light from the sun strikes the earth, a portion of it is reflected back, and that portion that is reflected back is of a longer wavelength. Longer wavelengths have less energy.

There is also no question that carbon dioxide absorbs light in wavelengths within the range of the wavelength of the reflected light. Anyone with a good old spectrometer can demonstrate this fairly easily.
When CO2 absorbs reflected light its kinetic energy can increase, which results in an increase in temperature.

So the basic science is clearly there. The issues surronding the basic are science are:

1. How much of an increase in global temperature results from a given increase in CO2?

2. How quickly will the increased CO2 be taken out of the atmosphere.

3. Are there any counteracting forces that will balance out the temperature increase?

4. What other other effects will result.

The answer to 1. is that scientists are currently predicting a change of a few degrees centigrade within the next century. I don't really remember how much a few is. A few degrees may not seem like much but it wouldn't take much to melt a significant portion of the permanent ice shelf in the Arctic and Anarctic.

The answer to 2. is that no one knows. Increased CO2 content may result in increased ocean alga which might process a decent portion. CO2 is also slightly soluable in water (this is where the fizz in soda comes from), so part of it might be absorbed by the oceans.

The answer to 3. is a mixed bag and is highly speculative. Some people believe that we were on our way into another ice age before we began burning fossil fuels, and it is possible that the forces pushing towards that ice age will counterbalance the green house effect.. A good volcanic eruption, like Mt. Minotubo (sp?) in the early 90's puts a great deal of ash into the atmosphere temporarily and that ash can have a slight blocking effect on the sun. These effects disperse after a year or two I believe. Conversely, a great deal of the heat being generated by the CO2 may be presently being absorbed by the conversion of water from ice to liquid in the polar ice caps. When the surface area for this decreases as a result of decreased mass of the ice caps, a more rapid increase in temperature could result.

The answer to 4 is a big mixed bag. It might help to explain the difference in annual temperature variation between the pole and the equator.

The poles and areas closer to the poles go through a larger range of annual temperature variation than the equator, largely because of the variation in length of day. Areas further out from the equator undergo larger variation. In Iceland, the night is only a couple of hours long at the summer solstice and lasts over 20 hours at the winter solstice. Closer to the equator the difference between length of day and night rapidly decreases. Naturally, greater differences in sunlight result in greater variation in temperature.

Thus, although in my neck of the woods we may dream of the day when our country becomes a tropical paradise, what will really happen is that the worst of days in our winters will get slightly less cold and days like today will become even more unbearably hot. Thus those who shrug and figure we can all just move closer to the poles when the temperature rises don't quite understand how much worse it gets the further out from the equator.

Incidently, the lower variation at the equator is also thought to be the reason for the greater biodiversity near the equator. Because temperature vary so much at the poles, all species are forced to become generalists capable of adapting to a variety of conditions. Generalists neccessarily occupy larger niches in an ecosystem, leaving less room for diversity. By contrast, specialists can exist more effectively where there is less seasonal variation, with the constant environment allowing for the development of specialized tools that may not function well outside a small niche, but being much more effective within that small niche.

As result scientists anticipate that biodiversity will decrease as temperatures increase. The specialized environment within which an organism has evolved will be destroyed when the temperature changes, but those species will not simply be able to move further out towards the poles because of the increased seasonal variation. Eventually if the temperature at the equator stablized biodiversity would return, but that could take hundreds of thousands of years.

I think that it is possible that temperature variation between the poles might decrease a result of overall temperature increases. Increased temperature is really increased molecular kinetic energy. Such an energy increase may also result in increased wind speeds. Increased wind speeds may result in more even planetary temperature distribution. I do not believe that those increased wind speeds will be able to totally nullify annual temperature variation and once again this is something I am only guessing at without any research I have read talking about it.

Of course, if I am right this may speed up the process of polar ice cap melting even more. I don't remember how much scientists have predicted that sea levels will rise as a result of global warming, but I believe that places like Venice and Bangladesh have problems already from increaseing sea levels.

If wind speeds as I suspect they might, we may have an overall increase in nasty weather and while average annual temperature change due to latitude may decrease, there may be an increase in overall weather variation. So we may get more and longer droughts at times, and nastier storms at others.

I'm a little less clear on the role water vapor may play. As temperature increases, the air's capacity to hold water also increases. The air during winter is very dry, while during the summer it can hold much more water which is where that sticky feeling we get comes from. Water requires more energy than most other molecules to increase its kinetic energy and therefore its temperature. I'm wondering if an increase in water vapor may act to buffer the increase from the green house effect.

Regardless of the possible effects, I do not believe it is realistic to abandon fossil fuels at this point. They are just too cheap and too concentrated a form of energy for us to stop using them. We need that cheap energy to build the goods people need to live, to be able to affordably care for the needy and engage in scientific research, and to transport needed goods from place to place. The resulting loss of world productivity from abandoning fossil fuels would result in a much greater loss of life than the problems which could arise from global warming. Global warming is a long term problem and our use of fossil fuels now may give us solutions to that problem later which will be less costly to our population as a whole.

In addition, human energy use results in at least some increase in temperature regardless of what source the energy comes from. Although most of power producing plants are located well away from major cities, there is a noticeable rise in temperature within those cities which can not be totally attributed to a localized accumulation of CO2. In the long term if human population continues to increase we may see global temperature increases regardless of the source of energy we are using.

Ok. I think that about covers it. Just the odd impulse to demonstrate the enormous power of my vast brain. (to engage in grammatical mistakes in large essay form)