The anthropogenic era (ed. - ie climate warming due to human intervention) is generally thought to have begun 150 to 200 years ago, when the industrial revolution began producing CO2 and CH4 at rates sufficient to alter their compositions in the atmosphere.

A different hypothesis is posed here: anthropogenic emissions of these gases first altered atmospheric concentrations thousands of years ago. This hypothesis is based on three arguments.

(1) Cyclic variations in CO2 and CH4 driven by Earth-orbital changes during the last 350,000 years predict decreases throughout the Holocene, but the CO2 trend began an anomalous increase 8000 years ago, and the CH4 trend did so 5000 years ago.

(2) Published explanations for these mid- to late-Holocene gas increases based on natural forcing can be rejected based on paleoclimatic evidence.

(3) A wide array of archeological, cultural, historical and geologic evidence points to viable explanations tied to anthropogenic changes resulting from early agriculture in Eurasia, including the start of forest clearance by 8000 years ago and of rice irrigation by 5000 years ago. In recent millennia, the estimated warming caused by these early gas emissions reached a global-mean value of ~0.8ºC and roughly 2ºC at high latitudes, large enough to have stopped a glaciation of northeastern Canada predicted by two kinds of climatic models. CO2 oscillations of ~10 ppm in the last 1000 years are too large to be explained by external (solar-volcanic) forcing, but they can be explained by outbreaks of bubonic plague that caused historically documented farm abandonment in western Eurasia. Forest regrowth on abandoned farms sequestered enough carbon to account for the observed CO2 decreases. Plague-driven CO2 changes were also a significant causal factor in temperature changes during the Little Ice Age (1300–1900 AD).

Ruddiman's critique embodies several key factors. First, he identifies key data that do not appear to be well-accounted-for in the popular theory (i.e. that current warming of the globe is the result of industrial activity including petroleum-based transportation). Second, in the body of the paper he analyzes that theory and demonstrates why it does not adequately account for the data. And third, he offers an alternative hypothesis which not only accounts for the climatic data but which also accords with emerging data from other disciplines (paleontology).

The result is a mature work which has gained the attention of many in the scientific community. It forms the basis for a possible debate regarding public policy in response to global warming. For the science doesn't make the issue go away -- it merely illuminates the nature of the various forces whose current balance led to an unprecedented 8000 year period of climate stability.

Ruddiman notes that human contribution to global warming in the 200 years or so since the start of the industrial age is equivalent to all previous contributions in the thousands of years from the start of agriculture to that point, and it is increasing. Will the natural cycles which would otherwise plunge the Earth into a period of glaciation, a new ice age, overwhelm that warming contribution? That is a question for science-based modeling and prediction. And if the models suggest that will happen, how long would it take and what changes in our environment would occur along the way if we do not take action to reduce our production of carbon dioxide and methane? How much could we slow the rate of warming if we tried and are the costs of such an attempt worth the likely outcome?

These are policy issues which need input from careful science. The discussion at realclimate.com that I linked above is one step towards that input, as Ruddiman's techniques for analyzing the data from Earth's past are evaluated for soundness and completeness. Other data may also be brought into the analysis. For instance, in the April issue of Analog magazine, Science Fact author and physicist Richard Lovett notes a 2005 paper by Matthew Sturm and colleagues that suggests that Ruddiman's model underestimates the impact of changes in Arctic vegetation on climate -- impacts which not only corroborate but strengthen his argument.

If Ruddiman's work demonstrates major flaws in the politically correct theories of recent human responsibility for climate change, it by no means should leave us complacent. Human civilization has flourished for the last 8000 years precisely because of a benign and stable climate in many parts of the world, a climate which was the result (if Ruddman's hypothesis is correct) of human activity (warming) balanced against the natural cycles of the earth in its orbit around the sun (at present, cooling). But Ruddiman notes that the human side of the equation has accelerated. CO2 levels in 2006 have reached levels the earth hasn't seen since the age of the dinosaurs. We are, Ruddiman says, heading into terra incognita. His work has, however, given new insights into climate change and, as his hypothesis is evaluated in detail, may help to inform policy decisions around the world.

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The reports say nothing about the type of weapon used. Most likely it was a co-orbital interceptor like the old Soviet system from the 1980s. That would be little more than a nuisance, militarily speaking. On the other hand, if it was a direct-ascent ASAT, it could be very significant, depending on its performance, on how many were deployed operationally, and how reliably US intel could detect deployment. A system of even modest performance would raise the stakes enormously in any conflict with China if we could not track its deployment. It would create the possibility of a quick succession of attacks destroying all our low-altitude spacecraft.

Keep an eye on this issue - and on the battles that will emerge in Congress with those who want the US to demilitarize its space activities.

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(This is long, but I do have a point that goes beyond the movie review. I welcome your responses and thoughts about how this applies to current events in Iraq and elsewhere.)

For those who don't remember the film (or haven't seen it), the plot is fairly straightforward. Seagal plays a Navy SEAL who was busted from the highly respected rank of Chief Petty Officer to lowly corpsman after striking an officer in an argument after a failed operation. He's now posted as the Captain's personal cook in the USS Missouri, a battleship on its last trip home before decommissioning. The Captain, who knows about his past, benignly allows him to keep a low profile (for instance, by avoiding dress uniform which would require him to wear his Silver Star, Bronze Star etc., which would reveal his past to the rest of the crew.)

The slimy and corrupt Executive Officer on the ship detests Seagal. He's already plotting to enable a rogue ex-CIA agent, played by Tommy Lee Jones, to hijack the Missouri and sell her nuclear and other arms on the black market. To get Jones and his accomplices on board to take over the ship, the XO plans a party for the captain complete with a stripper (played by Erika Eleniak, ex-Playmate and Baywatch actress). After confining Seagal in a refrigerated locker, ostensibly for insubordination but actually because he just can't stand him, the XO countermands the usual security procedures, leaving few marines on watch. When the party is going strong Jones and his mercenary band round up nearly all the ship's crew and lock them below decks, then take control of the ship.

The rest of the film, predictably, shows Seagal methodically escaping, figuring out what is going on and saving the day. It's HOW he does that, and how he's different from the XO and the rogue agent turned mercenary, that made this a popular film in the States, I think.

When we first meet Seagal's character, we don't know his past and he comes off as a cocky smartass who demands special treatment. But he's not unlikeable -- he makes a great bouillabaise, keeps the galley crew in good spirits. And there's the Captain's cryptic comment to the effect that "I don't know why you don't want to wear your medals. If I had those decorations I'd sleep in them!"

We also suspect Seagal's basically a good guy because the XO detests him and the XO comes off as (excuse the language) a pr*ck. He's status hungry, proud and overbearing and you can tell he disrespects the Captain for the latter's easygoing demeanor.

We learn more about both these characters later in the film, when Jones demands that the XO find out who that (now escaped) cook is. Seagal's personnel folder was in the now-dead Captain's private files and discloses the SEAL's identity, heroic past and official disgrace. On the other hand, we learn that the Captain had written up the XO for a psych evauation when the Missouri returned to home port because of the latter's abusive treatment of the crew. Whereas the SEAL accepted his demotion with quiet humility (more or less), the XO reacted to the well-deserved criticism of him by turning the ship over to Jones for a cut of the money they expect to earn.

Seagal's SEAL character is contrasted with Jones' rogue CIA agent in similar ways. We learn that the rogue agent had been responsible for some of the Agency's most spectacular covert ops but had spun out of control. The Agency tried but failed to kill him and the Missouri hijacking is his revenge. Jones delivers some deliciously over-the-top acting in this character, who is borderline psychotic but lethally dangerous nonetheless. In contrast, our SEAL -- equally accomplished -- not only accepts his punishment from the Navy but maintains his inward emotional and moral balance in response to his demotion and throughout the ensuing action on the ship.

While some of that apparent emotional balance is no doubt due to Seagal's limited acting range (to quote others, his emoting runs the gamut from A to B), it's significant that Seagal's personal martial arts background is in Aikido. Osensei ('great teacher', i.e. the founder of Aikido, Morihei Ueshiba) was known as the pre-eminent master of many Japanese martial arts in the early 20th century. However, despite his mastery of their techniques he felt something was missing in them. He found that 'something' in the spiritual teachings of a neo-Shinto school which emphasizes loving compassion to all and the unity of all beings.

This spirituality pervades Aikido teaching and practice, both in the cultivation of inner serenity while in the middle of conflict and also at the physical level in the flowing movements of the art and its emphasis on ways to counter force without inflicting more force, when possible. Unlike Karate-do, which overcomes force with superior force, the ideal outcome of an Aikido encounter is that the Aikidoka redirects an attacker's force without needing to counter-attack. My sensei called the various judo-style throws "helping the attacker get to where he's determined to go". However, when mastered, Aikido is arguably the most lethal of the open-hand martial arts. (It also incorporates weapons in the form of the Japanese sword.)

Which brings me to the No Ditz Left Behind principle.

Seagal's SEAL character in Under Seige is not identified as a Aikidoka, but he embodies many of the characteristics of one: the ability to blend into his surroundings (moving silently just beneath a group of mercenaries, for instance); exquisite sensory awareness (advanced Aikido exams may present the blindfolded candidate with multiple attackers at once); and mastery of a variety of techniques (open hand throws, punches, kicks, blocks, joint locks, knife work).

But perhaps the most characteristically Aikido element -- and, I will assert, American element -- of the Seagal character is the way in which he interacts with the ditzy dancer, who fell asleep before she was due to come out of the party cake and so was overlooked during the roundup of the sailors. Seagal knows something's very wrong but he doesn't know the nature of the ship takeover when he runs across this semi-hysterical bimbo belowdecks. His first thought is to hide her in a locker where she'll be safe while he investigates further, having already survived an attempt by two of the mercenaries to kill him.

The ditzy blonde will have none of that and makes so much noise he agrees she can come with him. It's a useful plot device, but from most perpectives it's highly improbable. Most contemporary scriptwriters would have the protagonist gag her and maybe knock her unconscious to get her out of the way. (Or would have her be cool, calm and a deadly shot.) But Seagal reacts as an Aikidoka would, by accepting the situation and seeing what he can make of it.

At first she's a lost cause. Depite pronouncing they're going to die, she seems unwilling to do much more than emote. When Seagal gives her a semi-automatic rifle and explains what he wants her to do, she responds, "I have two rules. I don't date musicians and I don't kill people."

Still, in spite of our exacerbation exasperation with this ditz -- and there is no better word for the blond stripper with well-endowed mammaries and seemingly not a clue in her head -- we tend to admire her spunk, I think. We're not really surprised when she ends up tossing granades with the best of them, any more than we were surprised when the XO turned out to be a snivelling resentful traitor. Or when the ex-SEAL takes on a difficult mission single-handed and succeeds despite being, at this point in his life, "just a cook" with a ditzy companion provided, improbably, by the Universe.

No Ditz Left Behind. Hollywood is enamoured with flawed, world-weary protagonists -- not 'heroes' -- but audiences know better. Seagal's character flows with events and integrates the stripper into his plan not only because she was making enough noise to alert the mercenaries, but also because she explains she did so because she's claustrophobic and couldn't stand to be shut into the locker where he wanted her to hide.

That same combination of compassion with strength, that willingness to put oneself at risk to protect others, gives power to photos we've all seen of US soldiers tenderly cradling children in Iraq. It's why the realism of the Brezhinski crowd in Washington doesn't resonate much outside the Beltway, even when the US public is war-weary and frustrated with the failure of Iraqis to step up to the plate and act as we hope we would after being liberated from the depredations of a tyrant.

The Iraqis have few stories like Under Seige and no aikido dojos to teach these virtues. The Arabs in particular are shaped by a culture with very different stories whose thrust, T. E. Lawrence notwithstanding, tends not to provide much training for service to others of this kind. But our culture does, and we can and should be proud of that fact.

We just need to realize that not all apparent ditzes rise to the occasion when given the chance.

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