What is claimed to be the first "green" search engine launched today, offering users in 14 countries the ability to contribute to offsetting carbon emissions through tree planting schemes -- just by querying the Web.

Ecocho is aiming to offset greenhouse gas emissions by sponsoring the growth of up to two trees for every 1000 searches users make through the ecocho site, which utilises Yahoo and Google search engine technologies.

The company has an agreement with Yahoo and Google to receive a percentage of advertising revenue. That money is then used to purchase carbon offset credits through the NSW government Greenhouse Gas Abatement Scheme, said ecocho founder Tim Macdonald.

"From that we've organised with the Global Carbon Exchange, a broker of government accredited carbon credits, to essentially retire carbon credits. The credits get taken out of service and that money goes towards tree growing projects that the [NSW] government runs," he said.

"So, the government says 'thank you, we've got that money and we're not going to spend it building roads or tunnels and bridges, but on tree growing projects'," Macdonald said.

The search engine launched in Australia, the United States, France, Germany, Italy, and a further nine other countries, with future international tree planting schemes to be conducted through government accredited projects in each country.

"If you look at pure numbers, in Australia alone you've got 800 million searches per month. If we can get just one or two percent of people to switch to ecocho that could make a dramatic difference for the environment," Macdonald said.

The accounting and auditing firm KPMG is responsible for checking the registering and retirement of credits, ensuring ecocho delivers on its aim to reinvest 70 percent of the site's revenue in carbon offset credits.

Macdonald said the ecocho team -- four young, environmentally-minded Australians -- will be disappointed if the site does not result in at least tens of thousands of new trees being planted.

"We've been pretty serious with the launch; the search technology is available in 60 different languages, and we've gone to the trouble of hosting sites in other countries in their native tongue," he said.