A "Hopenhagen Earth Body Guard" poster on a building in the centre of Copenhagen urging people to sign the climate change petition
The United Nations Climate Change Conference in Copenhagen is expected to last until 18 December, aiming for an international agreement to reduce emissions from greenhouse gases. BBC Wales environment correspondent Iolo ap Dafydd reports from the Danish capital.
As delegates, diplomats and more than a few journalists queue to get into the Bella Conference Centre, many are talking about COP 15.
It's not shorthand for Copenhagen, but an abbreviation for Conference of the Parties: a reference to the 190-odd countries which are members of the UN, whose representatives are expected here for 10 days of talks.
The 15 means this is the 15th meeting of states on climate change. So much then, that this summit is held up as being a "last chance saloon" for a binding international agreement on emissions. It's merely the latest, and there's likely to be a 16th, 17th and so on.
I've been to a few large European Union and G8 summits in the past 10 years. I've also reported from a few large sporting events. This could top everything.
It's a huge media event, of course, but will bring together over 90 world leaders, about 15,000 delegates as well as countless businesses, pressure groups, charities, and any group which feels concerned about the environment. There'll also be seminars, protests, demonstrations and different events during the next two weeks.
UN's top climate change official expressed confidence that the meeting would deliver: "Within two weeks from Monday, governments must give their adequate response to the urgent challenge of climate change," said United Nations Framework Convention on Climate Change (UNFCCC) executive secretary Yvo de Boer.
"Negotiators now have the clearest signal ever from world leaders to craft solid proposals to implement rapid action," he added.
"Never in 17 years of climate negotiations have so many different nations made so many firm pledges together..
"So whilst there will be more steps on the road to a safe climate future, Copenhagen is already a turning point in the international response to climate change."
The Danish capital is the focus of much of the world's attention
So how is this relevant to Wales? Well, apart from a number of Welsh protesters making their way here over the next few days, some assembly politicians are expected to remind the UN states (Wales isn't a full member - only as part of the UK) that most environment regulations are implemented at a regional or local level, rather than by national governments.
According to Welsh Environment Minister Jane Davidson, "between 50 and 80% of environment laws have to be dealt with at Wales' level of governance."
And as four Welsh universities pool together a combined knowledge bank of 200 scientists, the Glaciology Group, based within Swansea University is looking how melting ice in Greenland means higher sea levels.
This is one of the many mentioned side effects of climatic changes and, according to Dr Tavi Murray the team leader, a direct way in which Wales could be affected sooner or later.
"Most of the cities in Wales are on the coast so sea level rise which is happening because of climate change is going to impact on Wales in particular ways that are different to the rest of the UK," said Dr Murray.
Wetter winters, drier summers
Between now and 2080, scientists predict that Wales will also have milder, wetter winters, hotter and drier summers, more flooding and violent storms and gales - as well as benefits like a longer growing season and possible industry spin-offs. Tourism could flourish, for instance.
We are reminded by earnest politicians and environmentalists almost daily to "do our bit": recycle more, insulate our homes better, drive the car less, buy more local food and think about those cheap air trips we enjoy so much.
As our energy bills are going up, there are savings to be made from being a little more fugal and austere. Not the most comfortable idea before Christmas, perhaps, and Copenhagen, like all cities, is awash with bright lights and tempting shops.
So whether we understand or support cutting carbon emissions or not, if an agreement is reached on that and funding developing countries to curb their own emissions, there will be a financial price for the richer countries - Britain and Wales included. It may affect all parts of society - including businesses and industry.
As last week's Beaufort/BBC Wales survey suggested, the public expects governments in Cardiff and London to lead, but what if that leads to more regulations and higher taxes?
Non Rhys, policy manager for the Federation of Small Businesses in Wales, who sits on the assembly government's panel for climate change, said: "What we need to do, and what the government needs to do, is change the messages to make sure business realise that taking these measures can lead to cost savings as well.
"They can actually help their business, and we need to be using different terminology and really pursing this through now, as it's an opportunity for business to change."
In Copenhagen billboards with "Hopenhagen" scrawled in green across them are mushrooming everywhere, as are well-lit and expensive information panels reminding all those who read them, about the dangers of climate change.
The real danger is that this summit will be seen to fail what it has very ambitiously called for: a signed agreement on carbon emissions, to try to keep the estimated temperature rise to under 2C by 2100.
This contract between countries would follow the Kyoto Protocol, which runs out in 2012.
One thing is for sure - there will be plenty of talking.