Can capitalism and speculators' greed help solve the problem of greenhouse-gas emissions? That's the debate that's occurring right now as virtual marketplaces like the Chicago Climate Exchange (CCX) offer companies and trading firms a place to trade and profit from the output of carbon dioxide gas.

There are no US laws on the books that require corporations to control carbon emissions into the atmosphere. Membership on the exchange is completely voluntary. But carbon-producing members, such as Ford Motor, Honeywell, Dow Chemical and others, are required to cut their greenhouse gas emissions of the year 2000 by at least six percent by the year 2010. Cut them by more, and you can trade those extra percentage points, or "carbon credits," to other less-efficient members for money. By 'monetizing' greenhouse-gas emissions, the theory goes, companies will have incentive to cut their carbon emissions even further.

What happens if US laws were changed to reflect the mandatory carbon-emission caps, like those Europe already has? You can expect the price of carbon-credits to move higher, as less-efficient carbon-emitters stock up on credits while they figure out how to lower the amount of carbon-dioxide they put in the atmosphere.

A chart on the CCX already shows a rising trend in carbon-credit prices -- from less than $2 per 100 metric tons at the end of last year, to more than $5 per 100 metric tons now. CCX chairman and CEO Richard Sandor tells us the price began to spike during the Super Tuesday primary, when it became clear that the front-runners of both political parties -- John McCain, Hillary Clinton and Barack Obama -- all support caps on carbon emissions by US companies.