1."Reserves" are defined as what can be won from the Earth at a profit. So as the price goes up, and as technology improves, known, but sub-economic, oil deposits become economically feasible and move into the reserve column (whereas before they were just interesting mineral deposits — resources, perhaps, but not reserves). Also, we are presently doing a lot of exploring for oil, and continually discovering new reserves, more rapidly than we have for years.

But things are not bad yet. For the average family (average cars getting average mileage driven an average distance), an increase in gasoline price from $1.50/gallon to $2.50/gallon means an increase in their cost of living of about $50 per month, not enough to make people change their driving habits much, as we have seen from surveys recently published in major newspapers. When gasoline gets to $3.50/gallon or so, we will probably seek cheaper alternatives, such as shopping and commuting on bicycles. (Well, you and I do this now, right? So we won't save anything!)

If the price of coal goes up only a little per ton, the reserve figure goes way out into the future — 800 years is one number I have seen quoted. Keep in mind, however, that coal makes pretty good gasoline and jet fuel, but at a higher cost than conventional oil at present prices. And the cost of petroleum-based gasoline may soon (all too soon) be at $2.50 to $3.00 per US gallon. At some point it will become economical to make gasoline from coal, the technology for which is off-the-shelf — the SASOL company has been building such plants for more than 20 years, and will be delighted to build a plant for you. But that will consume the reserves more rapidly.

1. Anthropogenic forcing — culturally-induced elevated atmospheric CO₂
2. Variations in the energy output of the Sun
3. Annual changes in ocean currents, such as ENSO — the El Nino/Southern Oscillation.
4. Multi-decadal oscillations of the major ocean currents
5. Dissipation of atmospheric dust clouds from volcanic eruptions or meteorite impacts (following, of course, the global cooling periods caused by these dust clouds).
6. Changes in the spin and/or orbit of the Earth
7. Volcanic eruptions, which inject CO₂ injected into the atmosphere
8. Mudslides on the continental slopes, which release methane from deep oceanic gas-hydrate deposits

All of the above, and more, have been floated as potential drivers for global warming. The most widely recognized current model(s), on which the Kyoto Accord is based, assumes that anthropogenic forcing by industrial CO₂ is the only significant phenomenon at work in the current global warming. The other episodes of global warming don't seem to be addressed or even recognized. Since we know other episodes did occur, if we follow the popularly accepted model to its logical conclusion we would have to the postulate the existence of former civilizations with large fossil fuel consuming industries, something for which there is no archaeological trace. (A major industrial society in the early Tertiary? Before the human race evolved? Whee! Get me Hollywood on the phone, Miss Jones!)

6. Icecaps seem to have been present for only about 15% or so of Tertiary time (similar data to 5 above), which is one reason the sea level used to be so much higher.

7. The West Antarctic Ice Sheet, which could go pretty quickly according to some models, would put about half of the Earth's population out of their homes.

8. We might assume Californians don't conserve energy very well. After all, they did screw up their energy markets through a mix of the greed of consumer advocates who wanted to get electricity below cost, the naiveté of environmentalists who don't realize the physical limitations of alternative energy systems, and the inept planning of the California Electric Power Industry who made super profits until the state supply no longer met the demand.