Anyone looking for evidence of climate change would normally peruse scientific journals, academic reports and World Bank warnings. This week, one could just monitor the vapor trails over Bali.

More than 10,000 world leaders, activists, drought-stricken farmers, journalists, Nobel laureates, Leonardo DiCaprio, you name it, are jetting to the picturesque Indonesian island to save the planet. All those air miles are, of course, contributing to the very problems the United Nations climate- change treaty talks aim to tackle.

The 12-day conference may produce 100,000 tons of carbon dioxide and other pollutants, according to Chris Goodall, author of "How to Live a Low-Carbon Life." That's roughly what the African nation of Chad emits annually.

But hey, a few days in paradise sounds too good for many to resist. One wonders if the UN's confab would attract so many if it were held in, say, Rochester, New York. The New York Post summed things up with this headline: "Save the World (While You Tan)."

Yet it may make more sense to size up the issue — and avoid adding to Bali's sudden emissions boom — from 1,800 miles away in a city on the front lines of global warming: Bangkok.

Thailand's capital has the dubious honour of being among the 10 major cities most at risk from rising sea levels. Kolkata, formerly known as Calcutta, headed the Organisation for Economic Cooperation and Development's list of high-population cities vulnerable to climate change by 2070.

Also in the top 10 were Mumbai; Dhaka, capital of Bangladesh; Guangzhou, China; Ho Chi Minh City and Haiphong, Vietnam; Shanghai; Yangon, the capital of Myanmar formerly known as Rangoon; and Miami.

A recent UN report thickened the plot for officials in Bangkok. It found that Thailand's per capita carbon emissions stood at 4.2 tons a year, higher than China (3.8 tons), Indonesia (1.7 tons), and India (1.2 tons).

The point here isn't to single out Asia's ninth-biggest economy. That distinction might belong to the Bush administration, which refuses to follow the lead of Kevin Rudd, Australia's new prime minister, in ratifying the Kyoto Protocol. Having the biggest emitter of greenhouses gasses blowing off the only international emissions-limiting treaty undermines the entire effort.

Yet Thailand is an intriguing microcosm of the economic risks and political challenges involved in reversing global warming. That this nation of 65 million people has an election coming up thickens the plot even further.

When World Bank President Robert Zoellick talks about global challenges, he often focuses on so-called middle-income countries. Essentially, that means economies that are still developing, but whose governments have access to private-sector loans. Thailand is one such nation and it's among the vanguard of Asian economies entering a most challenging period.

Slowing global growth is putting Thailand's export-dependent economy at risk. Higher oil prices aren't helping at a time when trouble in global credit markets is amplifying the pain. And thanks to Federal Reserve Chairman Ben Bernanke's interest-rate cuts, the Thai baht is up 12 percent versus the dollar this year.

As if such stresses weren't enough, the military-installed government plans an election on December 23 to restore democracy following a September 2006 coup. After ousting Prime Minister Thaksin Shinawatra, the generals failed to convince investors that one of Asia's most-promising economies is in steadier hands.

Amid so many risks, leaders in Thailand and elsewhere in the developing world somehow need to find the resources and political will to address climate change. They also need to overcome a lack of urgency in developed nations, which should be doing more to share with poorer countries the scientific know-how needed to cut pollution.

"Those challenges are many and complex," says International Monetary Fund Deputy Managing Director Takatoshi Kato.

There will be negative consequences for output and productivity in many countries. Achieving development goals may be jeopardised by deteriorating fiscal positions as a result of weakening traditional tax bases and increased expenditure on the environment.

"There may be balance of payments problems in some countries owing to reduced exports of goods and services, such as agricultural products, fish and tourism and perhaps from the increased need for food and other essential imports," Kato said. "Also, I think there might exist a range of contingent risks to social and economic stability as a result of climate changes."

The scale of the challenge requires the kind of global leadership that is sadly lacking. It's great that former US vice president Al Gore is making headlines with his climate-change warnings. It's great that UN Secretary-General Ban Ki-moon is on the case, too.

Yet until the biggest economy and biggest polluter leads by example, what can we really expect from the Thailands of the world? What can we reasonably expect from China and India, which will struggle more than most with balancing rapid growth and reducing greenhouse gasses?

Thailand has as much to lose as any economy from rising temperatures. Even if Thailand cuts its emissions, though, it won't make much of a dent globally without the US doing the same.

This issue requires global leadership, and fast. Let's hope events in Bali amount to more than a bunch of bureaucrats getting a tan.

(William Pesek is a Bloomberg News columnist. The opinions expressed are his own.)