Kenya has emerged fourth in the world in the Billion Tree Campaign that was launched two years ago, after planting over 120 million trees.

With the view that seven billion trees will be able to off-set the carbon emissions of the world's third biggest emitter, Russia, environmentalists have embarked on campaigns to plant trees.

"It is global expression on taking action on climate change. We count every tree and every tree counts," said Tony Simons, deputy director general of the World Agroforestry Centre (Icraf).

With the initial two billion target having been met and surpassed, United Nations Environmental Programme (Unep) and Icraf have set a new target of planting an additional five billion trees.

The campaign, which is led by Nobel Peace Prize Laureate Wangari Maathai and Prince Albert II of Monaco, had initially set a target of one billion trees to be planted worldwide.

However, there are about 40 countries that have not joined the campaign.

The drive has seen heads of state, public and private sectors take part in tree planting, a move seen as one of the most effective ways of fighting global warming and improving food security. The World Food Programme has planted 60 million trees in 35 countries.

The focus has been Africa but Unep says it is spreading to other regions of the world.

Every year, 13 million hectares of the world's forests are cut down and this contributes to 20 per cent of the carbon emissions.

The top three participants were Ethiopia, Turkey and Mexico.

Eighteen months into the campaign, and with 155 countries participating, the grassroots response to climate change has seen two billion trees planted so far.