During his final day in the Danish capital, young reporter, Cerith, visits a number of exhibitions gathered under the banner of Hopenhagen Live, in Copenhagen's City Hall Square.
By Cerith, 16, from Ammanford, near Swansea
For BBC News School Report
Cerith is one of six Welsh Assembly Government Climate Change Champions
On my last day in Copenhagen, before returning home to the UK, I visited "The City of Hopenhagen Live", in the centre of the city. I was struck by how futuristic the "City" looked and how it was maintained in a sustainable way.
Let me explain: Coinciding with the United Nations Climate Change Conference, Hopenhagen is a campaign to give hope to future generations; the generations that will have to deal with climate change when its full and worst effects become clear to us. The campaign has taken over a large section near Copenhagen Corner, where there are numerous installations and exhibitions.
The most obvious instalment is the giant ball in the centre of Hopenhagen. In daylight hours, it looks like any other large, white ball, held up 50 metres in the sky, on stilts, but as day turns to night, the ball becomes a screen, with a rotating image of the Earth projected onto it.
By night, the white ball in the background becomes a model Earth
From a few streets away, in the nearby shops of the semi-pedestrianised areas of Copenhagen, it really does look as though a second Earth has arrived - which is quite ironic really, considering that many of us live as though we have two or three planets' worth of resources!
I was very impressed by "Future City" in Hopenhagen, where new and innovative policies and schemes from across the world were being exhibited and promoted.
'London to lead the way'
Alongside the UN Conference, mayors and governors from across the world also met in Copenhagen, for their own summit, to discuss what their respective cities should do to tackle the climate crisis.
A hybrid bus combines a conventional engine with an electric motor to reduce greenhouse gas emissions
All new London buses on the roads after 2012 will be hybrids
Mayor of London, Boris Johnson, took time out from talks at the Bella Center to take part in the Mayors' Summit, and pledged that London will become the electric vehicle capital of Europe.
As host city of the Olympic and Paralympic Games in 2012, Mr Johnson's explained his aim: that London's electric vehicle capacity will be so comprehensive, it will influence other major cities to provide electric transportation too.
Other schemes on display included the "Copenhagen Wheel" - a bicycle wheel that analyses air quality and personal health performance in order to send specific environmental data to councils - and a plan by the Mayor of New York to improve the sustainability of the Empire State Building.