Governments broadly support tough 2050 goals for cuts in greenhouse gas emissions but are split on how to share out the reductions, according to a new guide to negotiators of a new U.N. climate pact.

A document to be presented to U.N. climate talks in Bonn from March 29-April 8 narrows down a list of ideas for fighting global warming in a new treaty due to be agreed in December to about 30 pages from 120 in a text late last year.

It shows that there's an awful lot still to be done. And it also shows what needs to be done, Yvo de Boer, head of the U.N. Climate Change Secretariat, told Reuters on Monday of the text by Michael Zammit Cutajar, chairman of a U.N. negotiating group.

It's a good leg-up to a much more precise agenda focusing on filling in the gaps, de Boer said.

More than 190 governments agreed in 2007 to work out a climate treaty by the end of 2009 after warnings from the U.N. Climate Panel that greenhouse gases, from burning fossil fuels, would bring more droughts, floods, heatwaves and rising seas.

There is broad support by parties for a science-based indicative goal for the reduction of greenhouse gases to the middle of the century, the text says.

Possible goals include halving greenhouse gas emissions by 2050, deep cuts to limit a rise in temperatures by 1.5 or 2.0 degrees Celsius (2.7-3.6 Fahrenheit) above pre-industrial levels, or setting a low personal emissions quota for everyone.

PATHWAYS

It adds: There is a lack of convergence on the issue of the contribution by different groups of countries to the achievement of the long-term goal and pathways to it.

Rich nations say they will lead the way in making cuts but dividing up the burden between rich and poor is a huge tussle. Recession is making wary of commitments to shift from cheap coal, for instance, to more expensive renewable energies.

Still, De Boer said a distant 2050 goal was not irrelevant, for instance to an investor considering building a high polluting coal-fired power plant.

If I was walking my trolley through the supermarket about to buy a power station and knew that governments of the world are aiming for minus 50 percent by 2050 I know that it would influence my purchasing choice, he said.

He also said the text showed strong convergence on a need for ambitious mid-term targets for developed nations as close as possible to reductions of between 25 and 40 percent below 1990 levels by 2020 advised by the U.N. Climate Panel.

The numbers offered so far do not come close to that yet, he said. He noted that Japan, Russia and Ukraine have not even made proposals for 2020 cuts.

U.S. President Barack Obama wants to reduce U.S. emissions to 1990 levels by 2020, a 15 percent cut from current levels. The European Union has agreed 2020 cuts of 20 percent below 1990 levels, and 30 percent if other rich nations follow suit.

Zammit Cutajar said his text did not eliminate past proposals, but presented them in a more concise way. It doesn't take anything off the table, he told Reuters.

It's a good start but there's still way too many options, said Jake Schmidt, international climate policy director at the U.S. Natural Resources Defense Council.

The Bonn meeting will be a chance to see if the Obama administration comes up with new ideas. Former President George W. Bush was isolated from other rich nations in staying out of the U.N.'s Kyoto Protocol for curbing emissions until 2012.

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