NEW YORK — Across Uganda, thousands of women warm supper over new, $8 stoves. The clay-and-metal pots burn about two-thirds the charcoal of the open-fire cooking typical of East Africa.

Four thousand miles away, at a Land Rover dealership in London, a Range Rover Vogue sells for $151,000. A blue windshield sticker proclaims that the gasoline-powered truck's first 45,000 miles will be carbon neutral. That's because Land Rover is helping Ugandans cut their greenhouse gas emissions with those new stoves.

These two worlds came together in the offices of Blythe Masters at JPMorgan Chase & Co. Masters, 40, oversees the New York bank's environmental businesses as the firm's global head of commodities. JPMorgan brokered a deal in 2007 for Land Rover to buy carbon credits from ClimateCare, an Oxford, England-based group that develops energy-efficiency projects around the world. Land Rover is using the credits to offset some of the CO2 emissions produced by its vehicles.

For Wall Street, these kinds of voluntary carbon deals are just a dress rehearsal for the day when the U.S. develops a mandatory trading program for greenhouse gas emissions. JPMorgan, Goldman Sachs Group Inc. and Morgan Stanley are among those that are closely watching the climate-change talks in Copenhagen that aimed to reduce emissions of CO2, the most ubiquitous of the gases found to cause global warming.

The Kyoto Protocol, whose emissions targets will expire in 2012, spawned a carbon-trading system in Europe that the banks hope will be replicated in the U.S.

The U.S. Senate is debating a clean-energy bill that would introduce cap and trade for U.S. emissions. A similar bill passed the House of Representatives in June. The plan would transform the U.S. industry by forcing the biggest companies — such as utilities, oil and gas drillers and cement makers — to calculate the amounts of carbon dioxide and other greenhouse gases they emit and then pay for them.

Estimates of the potential size of the U.S. cap-and-trade market range from $300 billion to $2 trillion.

Banks intend to become the intermediaries in this fledgling market. Although U.S. carbon legislation may not pass for a year or more, Wall Street has already spent hundreds of millions of dollars hiring lobbyists and making deals with companies that can supply them with "carbon offsets" to sell to clients.

JPMorgan, for instance, purchased ClimateCare in early 2008 for an undisclosed sum. In December, it was set to pay $210 million for London-based Eco≠Securities Group Plc, the biggest developer of projects used to generate offsets.

Masters says banks must be allowed to lead the way if a mandatory carbon-trading system is going to help save the planet. And derivatives related to carbon must be part of the mix, she says, since they will help companies hedge their price risk over the long term. Derivatives are securities whose value is derived from the value of an underlying commodity — in this case, CO2 and other greenhouse gases.

"This requires a massive redirection of capital," Masters says. "You can't have a successful climate policy without the heavy, heavy involvement of financial institutions."

Yet Washington lawmakers are leery of handing Wall Street anything new to trade. And their focus is on derivatives. The most notorious derivatives are collateralized debt obligations, and the credit default swaps that were sold to insure them. Swaps are insurance-like contracts that protect bond holders against default. CDOs are bundles of subprime mortgages and other debt that were sliced into tranches and sold to investors.

"People are going to be cutting up carbon futures, and we'll be in trouble," says Maria Cantwell, a Democratic senator from Washington state. "You can't stay ahead of the next tool they're going to create."

In carbon markets, the derivatives would not be CDOs and CDSs, but futures, options and swaps that would allow a company to lock in a price for carbon like it would for any other commodity related to its business, Masters says.

"The worst thing would be to introduce legislation that doesn't achieve the environmental goal," Masters says. "That would be a crime of epic proportions."

Michelle Chan, a senior policy analyst in San Francisco for Friends of the Earth, isn't convinced. "Should we really create a new $2 trillion market when we haven't yet finished the job of revamping and testing new financial regulation?" she asks.

"What we have just been woken up to in the credit crisis — to a jarring and shocking degree — is what happens in the real world," she says.