The comparison between the Big 3 and the airlines is quite telling.

Detroit was never responsible for the results of its inefficient, poor handling cars until rather recently. Now that we have tire recalls, Superfund cleanup sites and Congressional mandates, Detroit is ready to reform.

The airlines, on the other hand, were always responsible for fuelling their products. They therefore had extreme incentives to maximize efficiency and performance. Their pollution impact may have been high, but at least they were working to reduce that impact through improved efficiency.

So, that leaves me with a simply conclusion: The US could likely improve fuel economy more rapidly by shifting the penalties of fuel inefficiency to Detroit.

Would a gas tax paid by Detroit (rather than the American consumer at the pump) have the desired effect?

...too many cave fires during the Pliocene epoch?

Global warming is real, but the last ice age just ended 10,000 years ago, practically yesterday in Earth’s 4 billion year time scale. Maybe Earth is getting warmer because it is typically more tropical? Considering that recorded history only covers about 2,000 years of Earth’s (that’s .00005%) it’s difficult to say what is “normal” since we don’t have much data.

Human activity is undoubtedly affecting climate. The U.S. Public Broadcasting Service television series “Nova” aired an episode titled “Dimming the Sun” which presented research demonstrating measurable differences in temperatures in the continental U.S. from September 11-14, 2001 when no commercial planes were flying. Contrary to expectations, no jet contrails meant warmer daytime temperatures and cooler nighttime temperatures by about two degrees Fahrenheit. More information is available at http://www.pbs.org/wgbh/nova/sun/contrail.html .

Humans can measure reasonably well and we know a few things about how the world works. However, humans demonstrate incredible hubris on a regular by failing to realize how little we know and how limited is our control. We actually seem to be surprised when an earthquake or tsunami flattens an entire region or a long dormant volcano impolitely erupts showing no concern for the inconvenience and death it may cause. In the grand scheme of the universe, we aren’t any more protected from extinction than the dinosaurs and we are just as powerless to protect ourselves.

My next car will be a hybrid, I’m adding insulation to the attic and worry about how the earth will support a global middle class when the earth's resources can barely support the nations that are rich right now. I’m doing what I can to support responsible living, but I’m open to the idea that nothing we do can change Earth’s inexorable march toward a more tropical tomorrow.

Appropriate measures can vary. Overseas flights basically have no substitute, notwithstanding what's left of the ocean-liner trade. If you cut overseas flights by say, a half, the number of overseas trips would basically be reduced by half too. (The actual reduction would be a bit less, of course, because flights would be more fully booked.) The same would be true in places like northern Alaska that depend on aviation.

If you reduced domestic flights, on the other hand, trains and buses could theoretically pick up the slack. (Such a measure, I hope, would only come after introducing gasoline rationing--a much more important measure-preventing cars from replacing flights.)

...the relative efficiency of a fleet of many smaller planes (regional jets) versus the cost of delays in the ATC system delays and in-air fuel burn costs caused by the larger number of small jets overall.

Efficient? Probably not.

'I’m doing what I can to support responsible living, but I’m open to the idea that nothing we do can change Earth’s inexorable march toward a more tropical tomorrow.'

The message has been simplified just to get it across, I think. 'Recycling things and fuel conservation are sensible' isn't a news story 'new study says we're all going to die' is.

I was buying a new printer a week or two ago, and a printer and cartridge was $40, the replacement cartridges were $50. I understand the economics - make the printer a loss leader, lock me into buying those cartridges, but *the first cartridge came with the printer*. When the ink runs out, it would be cheaper to *buy a new printer*.

And I don't need to see a picture of a sad polar bear cub to see that that's utterly insane, but at the same time, it's never going to be a talking point on a news show.

The airline thing has suffered from the same need to make a news story. There's still this idea that planes are for the 'jet set', that it's a luxury, that it's awash with money and glamor, unlike us ordinary joes.

I know for a fact that airlines don't burn a drop of fuel they don't have to. That, for the last couple of years, the most important people in the company are the guys buying the fuel, because a decimal point wrong costs millions.

I enjoy your columns very much, and I always find them to bring a refreshing point of view. But I have to call you task on your throwaway line "so-called peak oil". What, exactly, do you not believe about peak oil? That it's not going to occur? That it's not a legitimate factor in environmental debate? Peak oil will occur. I'm not going to argue whether or not we've already reached it, as some contend, or that it's in our near future, but either way, it will have a significant impact on every facet of our lives. If you look around your recycled house, I'm sure you will encounter numerous items (telephones), fabrics (polyester), and essentials (toaster, anyone?) that either are powered by fossil fuel, are made of fossil fuel (plastics), or both. Our entire economy and lifestyle is fueled, made of, and indebted to the existence of cheap fossil fuel. The way we eat, the way we do business, the airplanes you fly, the groceries we buy, the plastic bags we carry them home in - all of it is thanks to fossil fuel.

We've had a great 300 years, and who knows, we may have a couple hundred more, but it's unlikely. Because though we may only just now be approaching peak oil, our use of oil is skyrocketing so dramatically that we'll burn through the equivalent amount of fossil fuel in roughly one third the time. Down and out in a hundred years? Quite possible. But whatever the time frame, we will certainly begin to feel the pinch soon. We've cashed our one-time check of cheap fossil fuel, and there's no replacement fuel, no alternative fuel that is so easily accessible, so quickly turned into energy or product to allow us to sustain our current levels of energy consumption. And our current levels keep rising. We will all feel the pinch. Especially airlines.