The U.N.'s carbon offset market is likely to remain "in a coma" for years, project developers said, after countries failed to agree on measures to encourage demand at last week's climate talks in Warsaw.

Investment under the U.N.'s $315 billion Clean Development Mechanism (CDM) has ground to a halt as the value of the credits they generate has plunged 95 percent in five years to around 0.30 euros, crushing profits that investors count on to set up carbon-cutting schemes in the developing world.

"As a tradable commodity, it's in a coma and will be unless and until a 2015 agreement wakes it up," said Jorund Buen, co-founder and partner at consultancy and project developer Differ.

CDM credits can be used by companies and governments to help meet emission targets, but prices have crashed as industrialized nations delay setting new emission reduction pledges, while registered projects pump out more offsets at minimal additional cost.

The Warsaw talks were meant to advance a global climate accord to be agreed in 2015 and come into force after 2020, but no major nation offered to set or deepen emission targets, while Japan scaled down its 2020 goal.

The talks ended on Saturday with a recommendation that countries announce plans for contributions on post-2020 emission targets "by the first quarter of 2015 for those in a position to do so", which developers said was too weak to stimulate demand.

The text agreed by almost 200 nations "expressed concern" over the state of the CDM market, but measures that could have helped prop up the scheme were removed as developing nations insisted richer nations set emission targets first.

A proposal that parties should consider setting a minimum price for CDM offsets was deleted, as was a suggestion to invite financial institutions such as the Green Climate Fund to consider buying the credits.

The Green Climate Fund is designed to help channel up to $100 billion a year to developing countries by 2020 to help pay for projects to cut emissions and prepare for the effects of climate change such as rising sea levels and droughts.

Gareth Phillips, who chairs an association of project developers, said the Warsaw text was unlikely to trigger significant demand for CDM credits but added he was encouraged that the high level talks were beginning to address the issues facing the market.

POSITIVE STEPS

In the absence of new targets, several European nations firmed up pledges in Warsaw to pay a premium over market rates for a handful of CDM projects in the world's poorest countries to keep the scheme alive.

Also analysts said some hope for future CDM demand could come from a Warsaw statement clarifying that the units can be used by countries without legally binding emission targets to meet pre-2020 voluntary goals.

"With time this could bring some extra demand for CDM credits. We have seen a trend where some regional schemes accept credits predominantly generated within the same country, most recently Mexico and Korea," analysts at Thomson Reuters Point Carbon said in a note published on Wednesday.

Mexico is expected to launch a tax on carbon emissions in 2014 that allows companies to pay using carbon credits sourced from within the country.

South Korea is due to launch an emissions trading scheme in 2015 and has said its companies will be able to use CDM credits under the scheme if they come from domestic projects.

"For the most optimistic, this is the first sign of a life for CDM after 2020. If this is made more concrete ... it could lead to new investment in the last half of (the decade)," Point Carbon's Frank Melum said by email.