For Indonesian farmers, burning down rain forests is the cheapest and fastest way to clear land for palm oil and pulp and paper plantations.

The millions of acres they burn every year has made their Southeast Asian nation the world's third-largest producer of greenhouse gases. And, environmentalists warn, the powerful forestry and agricultural industry will likely stymie any efforts to crack down.

As difficult as it may be to hammer out a global climate deal in Copenhagen, implementing one could prove even harder.

From New Delhi to Washington, domestic political opposition, corruption, grass-roots intransigence and sheer bureaucratic incompetence stand as significant roadblocks to any agreement on emissions curbs.

Many across the globe are hoping Indonesia, with 10 percent of the worlds' forests, can be a leader in rain-forest preservation.

"But I think everybody has yet to realize how difficult this is going to be," said Frances Seymour, director-general of the Indonesia-based Center for International Forestry Research.

Using fire to clear land is illegal in Indonesia, but prosecutions are rare, said Greenpeace spokesman Brian Martin. Almost 18 million acres (7.2 million hectares) of land was burned during the last dry season from January to mid-October, said Ali Akbar, an activist from the Indonesian Forum on Environment.

While reducing emissions has broad political support here, activists question whether the government has the political will to take on mismanagement and corruption in the regulation of the forestry industry, which costs the country an estimated $2 billion a year.

"It will take strong action at the top levels of Indonesian government and international trading partners to halt the corruption in the timber industry," Human Rights Watch deputy program director Joe Saunders said.

The challenges are great across the world.

In the U.S., getting the treaty ratified, even by a Democrat-controlled Senate, will be a battle.

Republicans have charged that the emissions cuts President Barack Obama plans to offer at Copenhagen would cost jobs, making moderate Democrats nervous.

Some have urged Obama to be cautious about what he agrees to, knowing full well that the last time a U.S. administration signed an international climate treaty in the late 1990s in Kyoto, the Senate balked at ratifying it. The concern then _ and now _ was exceptions in the deal for developing countries, among the fastest-growing emitters of greenhouse gases.

Developing countries face their own dilemmas.

South Africa, facing severe domestic pressure to resolve energy shortages, is committed to building more coal-powered plants, angering activists.