COLOGNE (Reuters) - Confidence in the global greenhouse gas emissions market dipped slightly in 2007 despite a surge in the market's value, a survey of market participants released on Wednesday showed.

The Index of Greenhouse Gas (GHG) Market Sentiment, published by the non-profit International Emissions Trading Association (IETA) on the sidelines of a carbon markets conference, showed that 73 percent of 102 respondents were confident about the carbon market in 2007, down from 79 percent recorded in the previous two years.

According to a World Bank survey, also published at the conference on Wednesday, the global carbon market more than doubled in value to $64 billion in 2007.

The IETA survey consisted of six questions ranging from "is the GHG market an effective instrument in reducing emissions?" to "is the GHG market an attractive market which meets your organization's objectives?"

Around 83 percent of those surveyed saw the emissions market as an effective tool in fighting climate change, but only two thirds believed that the market was an attractive business proposition.

A number of setbacks now plague the global carbon market, instilling uncertainty which is dissuading potential investors.

Concerns over a delayed connection between U.N. and European Union emissions trading schemes and the postponement of the distribution of 2008 EU emissions permits by European governments to industry are examples of the concerns surrounding the $64 billion market.

The delay in a U.N.-EU link means that EU companies facing emissions limits cannot yet take delivery of carbon offets generated under the Kyoto Protocol, meant to be a key way of financing emissions cuts in the developing world.

Despite these issues, nearly all surveyed expected the carbon market to grow in 2008, and 90 percent expected the carbon market to survive past 2012, when the first round of the Kyoto Protocol expires.

The respondents were relatively equally divided among traders and investors, service providers, and compliance players including power installations and heavy industry.

For additional analysis on the carbon markets, go to http://www.reutersinteractive.com

(Reporting by Michael Szabo; editing by Gerard Wynn/James Jukwey)