So, what's going on in Copenhagen, how is business involved, and what matters to business here?

Last question first. In terms of the climate negotiations, a lot should matter to business over the medium to long term. For companies that have high emissions, or those with big opportunities to sell products and services that reduce or capture emissions, the climate negotiations are key to gaining certainty about how markets will change. The big emitters need this so they know how much they need to invest, and when, in low-carbon capital projects like clean power plants.

Those with new business opportunities want emissions constraints to transform markets as fast as their big customers can stand it without reaching the point where policy causes major financial and political disruption, and they want to know how heavily to invest in new clean technologies.

The Copenhagen talks are not likely to reach a complete new global agreement on climate, but it could frame out major pieces of a global deal and propel further progress in the months ahead.

Although how national governments set up national policies and regulations under a global regime will have a more immediate financial impact on business, international emissions limits -- or at least a cap on as many of the major emitters as possible (and clear path to caps for all major emitter countries) -- is ultimately the biggest issue for business.

Caps, combined with taxes and other policies, creates a price signal that will transform the economy and shift market demand for goods and services in favor cleaner technologies.

Also, emissions limits are a prerequisite for establishing global carbon markets, which offer the potential to reduce the cost of climate change for society but also to channel money to the most efficient investments in reducing or capturing emissions. The clearer and stronger the price signal in the market, the stronger the pull will be for early stage investment in next generation technologies.

But there are other big issues for business as well. Whatever the negotiators decide regarding technology diffusion and deployment -- as well as how to finance a major scale-up of R&D, demonstration, and deployment -- will materially affect companies doing international deals in advanced technologies.

Moving beyond notions of "technology transfer" is critically important. Key parts of the negotiations around technology and finance include whether or not a global deal involves any compulsory sharing or pricing of intellectual property and the shape of a global institution that might be created to support technology (or added to an existing body such as the U.N. or World Bank).

COP15 progress on forests and sequestration also matters to business. The greater the progress in opening up various types of forest conservation for offsetting emissions, and in allowing overseas forestry offsets to count for domestic emissions, the lower will be the cost to emitters of meeting regulations.

Another major issue for business heating up the talks in Copenhagen is trade measures against goods that have high embedded carbon. Carbon intensive manufacturers like steelmaker Nucor and utilities like American Electric Power that serve such manufacturers, are pressing the US government to include carbon border adjustments, claiming competitive risk from foreign producers that would not face carbon regulations.

Some labor unions agree. But other major global companies like Caterpillar and Intel argue strongly against distorting trade barriers, saying these could lead to higher costs for them and the potential for spurring retaliatory duties. Chinese officials have objected strongly that some fear border adjustments could launch a major rift in global trade relations.

These issues together shows another broad reason business should get more engaged -- at its core, a lot of the international climate policy challenge is around trade and investment. I and other former negotiators of these issues in the Kyoto Protocol believe the international trade and investment framework may be a better setting to tackle parts of the climate challenge -- at least the bureaucrats and negotiators in those arenas tend to understand better than their counterparts in the UNFCCC world how technology investment and diffusion actually happen.

There are more financially meaningful issues under the UNFCCC negotiations, but I'll leave that for another day.