The draft of a negotiating text for a new pact on climate change survived its maiden hearing at UN talks on Monday, providing a boost on a road still strewn with many obstacles, delegates and officials said.

Despite criticism from the United States and others, the document was "basically welcomed as a good starting point for the negotiations," said Michael Zammit Cutajar, who framed the text.

The June 1-12 meeting in Bonn gathers a 192-country forum tasked with steering the world to a new treaty that will whip the threat from global warming.

If all goes well, the accord will be finished in Copenhagen in December and take effect from the end of 2012, spelling out curbs on greenhouse-gas emissions by 2020 that will be deepened by 2050.

But the process has made only snail-like progress, hampered by discord between rich and poor countries as to how deep these cuts should be and friction between advanced economies over burden-sharing.

Cutajar, speaking in a webcast press conference, said the response from nations was "a good start to the session, a very positive mood, and I'm very pleased with that."

Further work would begin on Tuesday for addressing countries' reservations and whether it would be better to deal with these concerns in smaller groups or in a wider setting.

The text is likely to expand and become more complex as countries get down to the nitty-gritty, he cautioned.

Yvo de Boer, executive secretary of the UN Framework Convention on Climate Change (UNFCCC) stressed that the political mood for a deal had improved greatly since US President Barack Obama had come to power, but many problems lay ahead.

"Clearly there are some hard nuts still to crack," he said, noting that less than 200 days were left to the Copenhagen climax, amounting to just six weeks of negotiating time.

Almost all of the industrialised countries -- with the notable exception of Japan, whose position is expected in the coming weeks -- have now set out roughly where they stand on cutting their own emissions by 2020.

"They don't amount to enough," complained de Boer.

"(...) The offers that are on the table at the moment don't get us to the most ambitious scenarios put forward by the IPCC," he said, referring to the Nobel-winning group of scientists, the Intergovernmental Panel on Climate Change (IPCC).

Developing countries that have so far submitted proposals at the UNFCCC oppose signing up to legally-binding emissions cuts of their own, saying the cost of the pledges could imperil their rise out of poverty.

They argue that rich countries should take the lead by cutting their emissions by at least 25-40 percent by 2020 compared to 1990 levels to meet an IPCC scenario of limiting warming to two degrees C (3.6 percent) over pre-industrial times.

They are also calling for funds to help vulnerable countries adapt to the impact of climate change and gain access to low-carbon technology.

The most ambitious emissions plan so far comes from the European Union (EU) which has vowed to cut its own carbon pollution by 20 percent by 2020, and deepen this to 30 percent if another rich economy plays ball.

Under a bill put before the US Congress, the United States would reduce its emissions by 17 percent by 2020 but compared with 2005 levels.

But if the UN's benchmark of 1990 is used, this cut would be only four percent.

EU Commission representative Artur Runge-Metzger cautioned against moving the goalposts.

"It's not about making numbers match and making them close to each other, I think at the end it's a question of what's the effort behind it," he said.

He added, though: "It's easy to say we start from a clean slate and we forget what the EU has been doing in the past, and what kind of efforts, what kind of economic burden we have been putting on ourselves in order to move forward."

earlier related report
Climate change meet set to begin work on pact
Gruelling efforts to craft a pact on climate change enter a crucial phase on Monday when a 192-nation UN forum takes its first look at a draft text for negotiations.

The 12-day huddle in the German city of Bonn under the UN Framework Convention on Climate Change (UNFCCC) means that, after 18 months of swapping visions, the process will at last get down to the gritty stuff.

Little more than six months are left before the "Bali Road Map", launched in Indonesia in 2006, reaches its supposed destination at a Copenhagen summit: an accord that will transform global warming from a monster into a manageable problem.

On the table is a small mountain of paper whose notable feature is curly brackets, denoting discord among scores of submissions.

Despite the sprawling range of proposals, UNFCCC Executive Secretary Yvo de Boer said he hoped that the draft will be endorsed as a workable basis for talks over the coming months.

"There will be a negotiating text on the table for the first time," he told AFP.

"I hope it will be well received, that it will be seen as a balanced representation of the different ideas that countries have come with."

The big goal is to slash emissions of greenhouse gases by 2050 compared to 1990 levels.

But that's where consensus largely ends. Exactly how deep should be the cut be? How can it be achieved? And who should shoulder the burden?

In their proposals, many developing countries say rich countries, which bear historical responsibility for today's warming, should take the lead by cutting their emissions by 25-40 percent by 2020.

China has led the charge, demanding a cut of "at least" 40 percent.

But only the European Union (EU), which has set its own reduction of 20 percent by 2020, deepened to 30 percent if other advanced economies play ball, is anywhere near such a figure.

After eight long years of vilification, the United States is now being warmly embraced in the climate arena as Barack Obama bulldozes George W. Bush's policies.

But Washington is also warning that the world cannot expect miracles.

A bill put before Congress would cut US emissions by 17 percent by 2020 over 2005 levels using a cap-and-trade system of the kind Bush loathed.

This approach would translate to a reduction of only four percent compared to the 1990 benchmark, but it would also ratchet up to 83 percent by 2050, the top US climate change negotiator, Todd Stern, said in Paris last week.

"We are jumping as high as the political system will tolerate," said Stern, characterising China's demand of a 40 percent cut by 2020 as "not realistic".

Just as unresolved is what the emerging giant countries should do.

China is now the world's No. 1 polluter, and Brazil and India have also leapt up the emission ranks as their economies have grown.

Yet all refuse binding emissions targets of the kind that apply only to rich countries under the Kyoto Protocol, the UNFCCC treaty to be superseded from 2013 by the Copenhagen accord.