The bewildering soup of jargon used at the annual U.N. Climate Conferences has gained another pungent ingredient. It is REDD+, a mechanism to pay heavily forested countries not to cut or burn down any more trees in order to achieve their national emissions reduction goals.

But what may be one of the cheapest and quickest solutions to global climate change discussed by diplomats and experts gathering in Durban, South Africa, this week, may also be among the hardest to understand. The clunky acronym, which stems from Reducing Emissions from Deforestation and Forest Degradation, is an indicator of the communications problems it faces.

The goal of REDD+ is to provide a concrete system from which countries can gain compensation for preserving their forests. After all, deforestation is driven by people's need to make money from agriculture, logging and ranching. If done wisely, conservationists say they could use the same tool for an opposite effect.

Since its introduction to the U.N. climate talks in 2005, REDD+ has struggled to shed light on a deeply shaded world that includes the tricks of "carbon cowboys," the difficulties of accounting for forest emissions and the connection to the rigors of emissions trading. Then there are the burdens that indigenous people who live in many forests must live with. They often include deep-set poverty, long distance from responsive governments and the lack of basic legal rights they need to help them protect their environment.

The following Q-and-A is intended to be a primer for those who would like a more leisurely walk through this penetrable jungle:

What does REDD+ stand for?

Reducing Emissions from Deforestation and Forest Degradation. The plus sign stands for reforestation (planting trees where they once stood) or afforestation (planting trees in a barren area), elements that have been added fairly recently to the idea.

Who pays for REDD+?

For now, public and private funding from the United Nations, developed countries, companies and nonprofit sources goes to implement the infrastructure for these programs: tools for monitoring and reporting forest stocks, and hiring people to ensure that the program runs smoothly.

The idea is, once the framework for these projects is solid, there will be enough proof of emissions reductions to set up a forest carbon market. These markets will generate capital to continue to pay countries and landowners to save forests. The U.N. Food and Agriculture Organization (FAO) has estimated the potential value of forest offset credits on the carbon exchange to be around $600 million. That could be a lot more if compliance markets -- where sectors are obligated to buy and trade carbon credits under a cap-and-trade system -- begin to accept forest credits.

But the real funding comes from countries and institutions: an estimated $8.6 billion to date, according to the Voluntary REDD+ Database. Some high-profile examples are Norway's $1 billion investments to the Amazon Fund and the country of Indonesia.

While voluntary carbon markets buy and sell forest carbon credits, compliance markets do not yet accept them. The European Union's Emissions Trading System, the largest compliance carbon market in the world, has said it will not accept forest carbon credits before 2021.

Why is this important in the efforts to stop climate change?

Forest loss is responsible for about 17 percent of global carbon emissions, according to the Intergovernmental Panel on Climate Change (IPCC). That comes primarily from converting forests to cattle grazing lands, large-scale agriculture plots or urban development.

According to a 2008 study by Britain's Royal Society, the Amazon -- the world's largest rainforest -- could lose 55 percent of its forest cover by 2030, releasing between 15 billion and 26 billion metric tons of carbon dioxide into the atmosphere.

At the same time, potential benefits of keeping trees standing are enormous: Forests absorb about 2.4 billion metric tons of CO2 per year, according to a recent study by Australia's national science agency, CSIRO. That's one-third of the world's fossil fuel emissions.

Is it run by U.N.-REDD Programme?

No, U.N.-REDD is an collaboration among FAO, the U.N. Development Programme and the U.N. Environment Programme, formed in 2008 to to help developing countries prepare and implement national REDD+ strategies. But U.N.-REDD does not have oversight or control over all REDD projects.

This sounds like a great idea. Why is it so controversial?

Like any scheme that involves a financial reward, the possibility of making money opens the door to government corruption, dishonest businesspeople and cutthroat competition. Norway's $1 billion deal with Indonesia last year has been criticized for entrusting so much to a government with a long history of supporting logging and agricultural interests. Indeed, evidence of violating the country's moratorium on deforestation has already been documented.

The biggest complicating factor with REDD+ projects is that, unlike a solar array or a methane digester on a livestock feedlot, they mean people. An estimated 150 million people live in old-growth forests and use the resources -- trees for building and heating, land for agriculture, rivers for fishing and wildlife for hunting. In most cases, their lives are dependent on these resources.

Because of this, human rights issues have become tangled with REDD+. There have been reports of "carbon cowboys," individuals who set up a REDD+ project by convincing forest dwellers to sign away their rights to land, with a contract written in a language they do not speak.

The issue of land tenure has stirred the pot of complication. In Indonesia, almost all of the land is owned by the government, and concessions are leased to timber, paper and palm oil industries to do business. While the government may be the landowner on paper, the management of indigenous communities on the ground is often assured through oral tradition, passed on from generation to generation. This makes it difficult to prove who owns which parcel of land, and who should receive compensation for a REDD+ project.

Finally, in many cases these are communities that, throughout history, have had their forests exploited. They are mistrustful of any outsider looking to make money from forest resources, even if that money goes to keep trees standing.

How can we be sure that the accounting is correct?

Although there are margins of error in measuring trees to account for carbon, the science is relatively accurate, said Marc Steininger, scientific director of Conservation International's Science and Knowledge division.

"The funky part gets into the projecting into the future," he said. In order to measure progress, there needs to be a baseline, or "reference level." The reference level is the amount of deforestation carbon emissions a country would release in a "business as usual" scenario, and is evaluated by assessing historical trends in emissions.

So if, on average, the nation of "Forestia" emitted 100 million tons of CO2 per year between 1995 and 2005, that would be its reference level. Therefore, the country would be compensated for every ton of CO2 below 100 million tons annually.

But what if, given the booming economy and population growth, Forestia expects its emissions to be 120 million tons in the next decade, without a REDD+ program. Should the reference level be raised to 120 million tons of CO2?

Conversely, paying countries for progress away from a reference level rewards heavy land-clearers more than those who don't have a history of deforestation. If the baseline is low, there is less improvement -- and less money -- to be made. This is where the science slides into a political game among countries.

And while carbon counting is relatively easy on a small-project scale, things get complicated when an entire country needs to report how well forests have helped reduce emissions. A description of activities in the Democratic Republic of the Congo may not be clear to a U.N. staff worker in Geneva. Degradation, in which land is not clear-cut but trees are selectively removed, is also difficult to quantity. It is hard to identify degraded land on a satellite image.

Where will loggers, cattle ranchers, palm oil planters and soya farmers go if they can no longer clear forestland to stay in business?

Recent evidence of a dropping deforestation rate in the Amazon suggests that forest conservation and development need not be mutually exclusive. Advances in livestock productivity, agricultural technology and improved methods of land tenure mean more can be grown or raised on less land. In Indonesia, palm oil producers are being encouraged to plant on degraded lands, although legal blocks and a lack of economic incentives have slowed the pace of adoption.

Still, many environmentalists fear that industries that cut or burn down forests will simply move to a country that does not have a REDD+ program in place, resulting in no difference in net carbon emissions for the planet. This is known as "leakage." In South America, stronger conservation policies in the Brazilian Amazon could lead to deforesters moving to Guyana or Suriname, countries that have seen relatively little deforestation compared to their neighbor to the south.

How can we be sure that REDD is even needed?

Even if a REDD+ plan is executed perfectly, it may not make a big difference. Above all, deforestation is driven by global economic indicators: demand for beef, palm oil, timber or biofuels, as well as speculation on the global commodities market. But fluctuating markets, technology changes and stronger environmental laws could mean that the rate of deforestation would have gone down anyway, without any help from a REDD+ program. In that case, money for REDD+ would have been better spent on a different project to curb climate change. This future-telling conundrum is known as "additionality."

What is the future of REDD?

In a perfect world, it is one of the most inclusive and cost-effective ways to cut carbon emissions, engaging both developing and developed countries toward a common goal. But conflicts, both in the forests and in the halls of international climate negotiations, are making it hard to move forward.

For now, REDD+ remains at the pilot project level. Eventually, these projects will serve a country's commitments to reduce greenhouse gases. But as forest carbon projects move up from a project scale to a national scale, the country will need to have the ability to expand its REDD+ infrastructure and streamline information from a project to a subnational to a national level.

If REDD+ eventually relies on funding from carbon markets, there must be certainty of demand in compliance markets. The recently passed California cap-and-trade program has said it will begin accepting credits from REDD+ markets in 2015, but Europe's markets will not begin to consider REDD+ credits until 2020. By then, the structure of the carbon market may be very different from what it is now.

The horizon is still visible to negotiators in Durban. A financial commitment to REDD+ is expected this week, and the U.N. Framework Convention on Climate Change's scientific advisory committee has drafted decisions on how countries will decide reference levels. The committee has also mandated that UNFCCC countries submit reports on safeguards, but did not specify a format on how to do so -- a disappointment for several environmental groups.

Philosophers have pondered whether a falling tree would make a sound if no one were around to hear it. In this case, one may ask: If a tree stays in the forest and everyone notices, will it make a difference?