The COP 15 host city is a little greener today thanks to the efforts of 400 Copenhagen school children.
Accompanied by guests of honour, Nobel Laureate and Patron of the Billion Tree Campaign, Professor Wangari Maathai, and the Danish Ministef of Environment, Troels Lund Poulsen, the children planted 2,000 trees in the shape of a giant tree just five kilometres from the UN Climate Change Convention venue.
Once the trees - all local native species - start to grow, the formation will be visible from the air for passengers landing at the nearby Copenhagen Airport, the Minister said.
Prof Maathai received a rousing reception from the children.
"Dance and wave if you want to send a message to the governments meeting down the road that you want them to do the right thing for all the children," Prof Maathai said.
"You'll look back and be so glad you planted these trees, for you, your families and for your children, because you are looking after our world and the generations to come," she said.
Speaking at the event, UNEP's Director of Communications, Satinder Bindra, told the children they had made a special contribution to UNEP's Billion Tree Campaign.
"The trees you've planted today, on day three of the crucial climate change talks, will be added to the Billion Tree Campaign tally and you can be very proud participants," Mr Bindra told the young crowd.
"You've planted 2,000 seedlings and next year you've got to go back to your schools and say 'Let's plant 20,000!'", he said.
Prof Maathai and Mr Bindra were presented with a silver spade with an engraved blade to mark the planting of 360,000 trees for the Billion Tree Campaign, 100,000 contributed by Replant the Planet and 260,000 by LEAF, a leading eco-schools programme active in 58 countries.
Making the presentation, the Coordinating Representative for LEAF, Bjørnstad Helge Bjørnstad, thanked Prof Maathai for inspiring him and thousands of others to get planting.
"Your life's work has been an inspiration for many of us, through demonstrating that planting a seed can create a legacy which will last many lifetimes, so thank you for coming here today to lend your support," Mr Helge Bjørnstad said.
More than 100 school children rode their bicyles to the event, which included lessons on tree planting and climate change.