A legally binding global agreement on the reduction of greenhouse gas emissions will take years to develop and adopt, delegates at the Copenhagen climate change conference said, citing huge differences among key players.

Sharp differences over emissions reduction persisted among the big polluters such as the US, Europe, China and India, dashing hopes among poor countries that help could come in their fight against climate change-related shocks in their economies.

Without a new agreement, developing countries will have to rely on the provisions of the Kyoto Protocol to benefit from opportunities emerging in the fight against climate change.

The protocol allows companies to fund green projects such as wind-generated electricity in exchange for carbon emissions.

Poor countries had hoped that the Copenhagen talks would offer a new roadmap for the fight against climate change by setting new emissions caps for developed countries.

Such a deal would also have committed the developed countries to support climate change projects in the poor world.

The support was expected to come in the form of financing of farmers to grow drought-tolerant crops where climate change has disrupted rainfall patterns.

The World Bank's most recent estimates said such an effort would require between $75 billion and $100 billion a year from 2010 to 2050.

"The political deal is what is likely to be the outcome," said Denmark's Climate Minister Connie Hedegaard.

A deadline then could be set when the legally-binding agreement will be finalised.

A political deal will not be legally binding and will be more of a voluntary commitment.

Officials here said the legally binding deal is not possible because the agreement for such ought to have been signed six months ago, which did not happen.

African countries have been lobbying for an agreement that would clearly state by how many tonnes of carbon dioxide emissions developed countries are prepared to cut and by when.

A political deal would mean that although commitments to cut emissions and finance adaptation activities may be made, they will be voluntary.

Carbon dioxide is the principle cause of the global warning, which has led to change in climate patterns and in turn affected weather conditions in African countries, most of which depend on rain-fed agriculture to feed their people.

Pastoralists too in Africa depend on the rainfall to grow natural pasture that feeds their livestock.

"US and the European Union are for a political agreement but the non-profit groups are outraged by this kind of an agreement," said Mike Shanahan of International Institute for Environment and Development (IIED).

Failure for a legally binding deal will leave Africa with the option to negotiate for the extension of some of the central features of Kyoto Protocol beyond 2012 when the existing commitments expire.

The protocol allows developed countries to reduce their emissions by supporting carbon reduction projects like solar-generated electricity.

Clean Development Mechanism (CDM), a system central to the protocol, allows emission-reduction projects in developing countries to earn certified emission reduction (CER) credits, each equivalent to one tonne of CO2.

These CERs can be traded and sold, and used by industrialised countries to a meet a part of their emission reduction targets under the Kyoto Protocol.

"If the Kyoto Protocol commitments expire without an agreement yet to replace it, then this CDM will end," said Patel Gurji, an observer in the negotiations from India.

CDM projects like those involving wind, solar, geothermal and biogas generation among others are emerging key areas where Africa is participating and gaining from climate change phenomena.

Most recent data released by Unep showed that a total of 112 Africa projects are at "validation, requesting registration or registered" stages of CDM.

All are worth Sh212 billion a year. This is up from 78 projects in 2008 and just two in 2004.

A new deal lobbied for by Africa would have included this feature, plus commitments to support activities like afforestation because trees act as carbon dioxide sinks and the recognition of agriculture as one of the activities that reduces carbon dioxide in the atmosphere and commitments to support it financially.

Some African countries are already announcing their way forward in climate change issues based on such expectations.

South Africa for example announced on Monday that it will reduce its current emissions by 42 per cent by 2025 but on condition that Copenhagen climate change talks results in a deal that will guarantee and finance, technology transfer and capacity building assistance from the developed nations to developing countries.

The UN Framework Convention for Climate Change said that developed countries would need to provide fast-track funding on the order of at least $10 billion a year through to 2012 to enable developing countries to immediately plan and launch low-emission growth and adaptation strategies and to build internal capacity.

At the same time, developed countries would need to indicate how they intended to raise predictable and sustainable long-term financing and what their longer-term commitments would be.

Kumi Naidoo, the director of Greenpeace - a non profit group vocal on environmental said anything short of a binding treaty in Copenhagen would be a political failure.

"The science is clear. We have to change the politics," he said in a statement.