It is not for nothing that the pithily-entitled 15th Conference of the Parties to the United Nations Framework Convention on Climate Change, or COP15 for short, has been described as "the most difficult talks ever embarked upon by humanity".
Some 17,000 delegates, campaigners and journalists will all be attempting to make their voices heard. A total of 98 leaders and heads of state will be in Copenhagen at some point during the two-week summit with most, including French president Nicolas Sarkozy, left, and German chancellor Angela Merkel, below, attending for the crucial final two days on 17-18 December. The prime minister Gordon Brown is also expected to attend in the second week. A notable exception to this is Barack Obama, above, The American president, and potentially the most important individual to attend, will be arriving for one day only next Wednesday before departing to Oslo to pick up his Nobel Peace Prize. The White House insists that Mr Obama's early and brief attendance to provide "impetus" to the talks.
Who isn't going?
The guestlist for the meeting is constantly changing with politicians calculating the pros and cons of being associated with the success or failure of COP15. Both the prime ministers of New Zealand and Canada this week performed U-turns and said they will travel to Denmark after insisting they would be staying at home. But question marks remain over the presence of the charismatic Bolivian leader, Evo Morales, and Dmitry Medvedev, the Russian president. Some 3,000 Danes who paid for tickets to an audience with Al Gore, above, yesterday heard the news that the event, and his attendance, had been cancelled.
The venue – Bella Centre
Built in the 1970s, the sprawling concrete and glass Belle Centre on the southern edge of Copenhagen will be the focal point of the conference after a multi-million pound facelift to ensure a 20 per cent cut in its C02 emissions as delegates shuttle between dozens of plenary sessions and fringe meetings.
The UN itself admits that the fortnight's proceedings will produce 40,500 tons of CO2 – equivalent to the entire annual output of the Pacific Island nation of Kiribati, which is so likely to be obliterated by global warming that its leaders are looking to buy land abroad to relocate its people. As a result, the organisers are at pains to underline the measures they are taking to minimise the carbon footprint of the talks. They include: the provision of Copenhagen tap water rather than bottled water to delegates; biodegradable cups and glasses that will be turned into biogas after use; free public transport for all delegates; and a guarantee that 65 per cent of all food and drink on offer will be organic. The Danish Foreign Affairs Ministry, which is meeting the £60m cost of the summit, is paying £800,000 to offset the carbon emission by funding 20 efficient brick kilns in Bangladesh. And if anyone was expecting the traditional "goodie bag" provided by conference hosts, they will be disappointed. Pointing out that such baubles "often end up in garbage bins", the Danes have banned such freebies and spent the money on funding 11 university scholarships.
As expected, there is a full programme of events for green protesters in Copenhagen. The Camp for Climate Action, which took to the streets of London during the G20 protests, plans to storm the conference site on 16 December, the day the high-level ministerial phase kicks off, "using only the force of our bodies". Churches across Denmark will be ringing their bells 350 times at 3pm on 13 December, in recognition of the 350 parts of CO2 per million that represents the safe upper limit for our atmosphere. Five dedicated stuntmen are also planning to set themselves alight in front of the UN building in New York on Monday. Denmark has rushed through a gamut of tough new laws including an automatic 40-day prison term for anyone found guilty of "inhibiting police work" and a power to detain an individual for 12 hours without evidence of a crime.
Of course, it is not just heads of state and political bigwigs who will be in attendance over the next two weeks. While officials burn the midnight oil thrashing out the fine detail of emissions targets for 2020 and "additionality", a number of celebrities will be flying into Copenhagen to add their voices to the pressure for a deal. Hollywood A-list climate fanatic and Toyota Prius driver, Leonardo DiCaprio , top right, will be there, along with British fashion designer Vivienne Westwood main picture, and Daryl Hannah. Supermodel and photographer Helena Christensen, above, is putting on an exhibition of photos of Peru in an effort to highlight how climate change is affecting the country. Archbishop Desmond Tutu, above right, will be presenting testimonials from people around the world who've been affected by global warming. Prince Charles will be there for a few days too, while royalty of a different kind, Sting's activist wife Trudie Styler, has also said she hopes to attend, along with Bollywood superstar Rahul Bose, who will be pushing for the Indian government to make a firm commitment on curbing emissions. Campaigners are concerned that the influx of glitterati could distract attention from the summit's main purpose. "It's the only thing we're being asked about," said an exasperated Greenpeace spokesman.
The climate change deniers
No gathering of the climate change clans would be complete without the vociferous contribution of those who believe it is all unnecessary. Leading the delegation of those considered by many to be the "flat earthers" of climate change will be James Inhofe, the Republican senator of Oklahoma, who once described global warming as the "greatest hoax ever perpetrated on the American people". He will roll into Copenhagen at the head of a climate "Truth Squad" whose role, among other matters, will be to highlight a pledge that any deal in the Danish capital will be thwarted in the US Senate. Other attendees on the sceptical side include Bjorn Lomborg, above, the Danish political scientist who has argued that the money spent on battling climate change would be better spent battling global disease. There is even speculation on Right-wing US blogs that the naysayers crossing the Atlantic just might include Sarah Palin.
When is the crunch?
The fortnight will be characterised by hundreds of meetings of the bodies that make up the UN climate change bandwagon. But it will not be until the final 48 hours of the vast gathering that the crucial decisions will be made. On 17 December, the cohorts of presidents and prime ministers will arrive in the Danish capital for the final round of horse trading to see whether faint hopes of a binding treaty can be resurrected rather than settling for a less stringent declaration. With preparatory talks widely considered to have failed to make sufficient progress, it is likely that even as Gordon Brown takes his place at the state gala dinner hosted by Margaret II, Queen of Denmark, right, last-minute bargaining will still be taking place. If a deal is struck, a traditional end-of-summit photo shortly before lunchtime on 18 December will announce the first binding global deal to reduce emissions. Either way, the process will inevitably move into 2010 to iron out the details.
How will we know if the deal is a good one?
A comprehensive and successful deal will require significant progress in three crucial areas. Firstly, the industrialised nations must sign up to a legally-binding reduction in their greenhouse gas emissions by 2020 of between 25-40 per cent on 1990 levels. Scientists say 2020 is the latest date by which global emissions must begin to fall. America has so far pledged only to cut its contribution to global warming (the largest per capita on the planet) by 17 per cent based on 2005 levels – equivalent to just 3 per cent on 1990. Secondly, the G77 group of developing countries and China will need to make a binding pledge to move beyond their "business as usual" negotiating position. China and India have already put forward offers to reduce their "carbon intensity" – the amount of CO2 produced relative to their economic growth. Thirdly, and most crucially, a deal must be thrashed out between the richest nations and the developing world to pay for the costs of poorer countries limiting their emissions and dealing with the effects of climate change. The G77 has demanded an annual payment of one per cent of global GDP, about $400bn (£240bn), to offset the devastation of global warming. The poorer nations are also insisting that any money should be in addition to existing pledges. So far, the only response from the industrialised world has been a suggestion from the European Union that a fund worth £90bn be established. It is this yawning financial gap, more than anything else, that could yet scupper a deal.
The Danish view
For the past 12 months, Denmark's 5.4m citizens have been bombarded with instructions on how to be on their best green behaviour for the Copenhagen summit by taking short showers, changing light bulbs, cycling to work and eating less bacon.
To their credit, the Danes have stepped up to the challenge. Copenhagen's famous Tivoli Amusement Park ,below, is switching to energy-efficient light bulbs and the city's buses are running on biofuel. The Christmas tree in City Hall Square, which has 7,000 lights, will only work this year if there is enough power being generated from the 15 exercise bikes hooked up to a generator. Climate change is now a compulsory part of the Danish school syllabus, while a television show aimed at teenagers has introduced a global warming "nerd quiz" with prizes for knowledge of how emissions warm the planet. Even Copenhagen's prostitutes have pledged to do their bit to ensure the meeting is a success. A bid by the city's Lord Mayor to reduce prostitution by sending postcards to 160 hotels urging delegates to "Be sustainable – don't buy sex" has met with a robust response from the Danish Sex Workers Interest Group: anyone turning up at one of the city's legal brothels with one of the postcards can have one on the house.
What happens next?
Whatever the outcome of the Copenhagen fortnight, the climate talks will go on. Failure to reach an agreement on a legally-binding treaty will create intense pressure for a deal to be struck at the next Conference of the Parties (COP) due to be held in Bonn next June. Ed Miliband, the climate change secretary, has already said he would want to see the Copenhagen process concluded before the next main meeting, COP16, due to be held in Mexico next December. The United Nations has already started planning COP17, likely to take place in South Africa in 2011, and COP18 in Asia in 2012.