The painting beat competition from over 630,000 entries to claim the top prize of US$2,000 and an all-expenses-paid trip to attend the next Tunza International Children's Conference on the Environment.
Second prize was awarded to 14-year-old Ka Mun Leong of Malaysia for her colourful painting of a clock divided in two - half of which shows pollution, fires and smoke-billowing factories, with the rest of clock face depicting a clean river surrounded by trees and animals.
Ka Mun will receive US$1,000 and a trip to the Tunza Conference, along with six regional winners. They are: Carolina Ferreira, Cape Verde (Africa); Atthapon Wirojrat ,Thailand (Asia Pacific); Durnea Iurie, Moldova (Europe); Waldir Tokuda, Brazil (Latin America and the Caribbean), Mitchelle Lai, Canada (North America); Postwalla Dariyash, Bahrain (West Asia).
Joint 3rd, 4th and 5th prize winners will receive certificates.
Children from across the world were invited to submit artworks on the topic of 'Green Communities'. From lions and humans playing a snooker match on a map of the Earth, to a team of animal doctors and nurses operating on a sick planet, young artists from across the world tackled the theme with imagination and flair.
"Participants in the International Children's Painting Competition continue to inspire the judges with their creativity and enthusiasm for the environment", said UN Under-Secretary-General and UNEP Executive Director Achim Steiner.
"On behalf of UNEP, I congratulate Diana Fan and the other prizewinners on their achievements. Their colourful artwork sends a clear message that we are all part of the global green community, and that by leading more sustainable lives, we can ensure that the rich, diverse environments depicted in these paintings can be supported for generations to come."
The International Children's Painting Competition is UNEP's flagship art and environment event. Since 1991, it has received more than 3 million entries from children in over 190 countries.
The competition is organized in partnership with the Japan-based Foundation for Global Peace and Environment (FGPE), Bayer and the Nikon Corporation.
"It's impressive to see the children's level of awareness of environmental issues and how they use their imagination to express this in pictures," said Dr. Michael Preuss, head of Corporate Policy and Media Relations at Bayer.
"The winning picture expresses the hopes and fears of the younger generation and is an appeal to everyone to actively support the conservation of nature."
Ms. Tomoko Yano, Secretary General of Foundation for Global Peace and Environment (FGPE) said, "We were afraid that the theme of "Green Communities" might be a little difficult for children to understand. However, we were happy to find that most of them tried to understand this important issue and described it with imagination and great ideas."
"We hope the children's artworks will keep encouraging people around the world to take actions together for present and future generations," added Ms. Yano.
With the winners of the 21st competition now announced, the search for next year's top paintings has already begun.
Today UNEP officially launched the 22nd International Children's Painting Competition under the theme: Water: Where Does it Come From? The theme supports the 2013 UN International Year of Water Co-operation.