Yes, you read it right: the negative value of a newborn child that results from his presumed exacerbation of global warming, which impact O'Neill and Wexler actually say necessitates certain CO2 abatement procedures.  As they have put it in still other words, "the economic activity of the additional child and its descendants will produce greenhouse gases which, if not offset by compensating reductions, will increase the level of greenhouse gases in the atmosphere, the amount of climate change, and the climate-related damages on society."

The concept discussed by O'Neil and Wexler can best be described by the word externalities, which they define as "costs or benefits associated with the birth of a child that fall on society but are not considered in the parents' fertility decisions."  They, however, along with many other like-minded thinkers, are very intent on considering these matters for them, as well as helping parents decide, either on their own or with negative monetary incentives provided by government, what to do about them.

Externalities come in many forms; but they can all be squeezed into two mutually exclusive categories: environmental and non-environmental.  On the non-environmental side of the ledger, externalities associated with the birth of a child in the world's less developed countries are generally negative; but in the United States they are strongly positive.  In the environmental category, however, it's an entirely different story, especially when the externality is the "greenhouse externality," which is calculated by O'Neill and Wexler to occur as a consequence of paying for measures required to stave off presumed - but unproven - CO2-induced global warming.  Although many different assumptions can influence the calculations, their "most relevant greenhouse externality results" are a $4,400 cost per birth in less-developed countries and a $28,200 cost per birth in more-developed countries, calculated over the period 1995-2100.

But this concept is only theoretical, right?  It doesn't mean that a "birth bill" will actually be levied on parents, does it?  Probably not, at least for now.  But what man can conceive, there is a high likelihood he will someday do.  And history teaches us that if man can conceive of a tax, its implementation will not be far behind.

Consider, for example, these ominous remarks from O'Neill and Wexler, which spell out the possibilities in very clear language:
1. "Externalities cause inefficiencies in the economy, and their existence is often viewed as grounds for intervention in order to improve total social welfare."
2. "In principle ? efficiency would be served by imposing a tax on births equal to the net value of the externality."

Even more chilling than these remarks are what O'Neill and Wexler have to say about childbearing itself:
1. "The existence of a greenhouse externality strengthens the case for population policies that lower fertility."
2. "A hypothetical social planner acting in the interests of all parents could increase social welfare by dictating a fertility rate different from the rate parents would choose on their own."

Chilling words indeed.  A "social planner" could actually dictate that a husband and wife may not have as many children as they might want.  And in the name of the climatic salvation of the global commons, the social planners could impose their will on all the world.

Most of us would hope that the irrationality that drives the climate alarmists would never lead to such an extreme regulation of our most cherished God-given right.  But all it takes for that to happen is for climate realists, who know better, to keep silent.  It is already, in fact, a sad commentary on our times that each new passenger on Spaceship Earth is no longer quite as welcome as were his predecessors when they began their trip through mortality.  And with ever more studies of the ilk of O'Neill and Wexler's making the unthinkable a subject of legislative debate, the presumed climatic burden of each new individual's CO2-emitting baggage will soon be seen as just too great to bear.  Then will the social planers step forward and become our saviors.  And then it will be too late.  Yes, today's child may still have a ticket to ride, but tomorrow's may not.  God help him.  God help us all.