To fly above the islands on the Jamuna River in Bangladesh is to see, close up, the physical effects of climate change. Here is a set of islands literally sinking into the sea. Meeting the local villagers, it hits you: the argument that global warming ravages the world's poorest people more than anyone else is so much more than just a cliché.
The main island, which will disappear in the lifetime of many of its inhabitants, frequently suffers major floods, the worst of which was in 2007, leaving behind rapidly spreading disease, homelessness and starvation. Firoza Khatun, a 25-year-old mother-of-three, told me: "In 2007, the water came up to my waist. We tried to stay in the house, we raised our bed higher on bricks and bamboo, but when it came to my waist we had to leave . . . We saved the roof but lost the house. We only had food for five days. I was scared."
Before my trip with the Climate Change Secretary, Ed Miliband, and the International Development Secretary, Douglas Alexander, I was shamefully in denial of this truth. Like others in a mercifully shrinking minority, I saw "climate change" - that technocratic, uninspiring term - as a second-order, middle-class preoccupation, somehow separate from poverty itself. But visit Dhaka, Bangladesh's capital city, and the link between the two becomes undeniable.
Thankfully, some progressive politicians have been quicker to recognise the importance of the environment to the social-democratic cause. In 2006, Ken Livingstone, guest editor of this issue of the New Statesman, warned in the Guardian: "I just do not think that politicians understand the implications, which at the very extreme is the end of most large life forms. If we slip into irreversible climate change, it means hundreds of millions of people migrating, and deaths. It means the poorest being hit the hardest."
Today, Labour ministers see climate change as a crucial part of their politics. As Alexander told me during our flight over Bangladesh: "I came into politics to change things . . . For our generation of progressive politicians, climate change is the defining test."
Alexander is helping Miliband in the seemingly impossible task of bridging the gap between a developed world (which must be forced to lead the way on carbon emissions cuts) and a developing world (which has often been reluctant to skip the conventional forms of industrialisation previously enjoyed by the west). As Miliband pointed out in Delhi, between 1850 and 2000, 30 per cent of carbon emissions came from the United States, 27 per cent from the European Union, and 7 per cent from China. There is a clear inequality of responsibility, but today the daunting task is to make the whole world carbon-conscious. NGOs talk of the west's "debt" to the developing world and Miliband accepts our "historic responsibility". On 10 September, the EU environment chief, Stavros Dimas, declared that rich countries should be paying €100bn a year by 2020 to cover the cost of mitigation in developing countries, with €15bn coming from the EU itself. It was the first time the EU had acknowledged the cost of global warming to poorer regions.
This is the backdrop to the negotiators' dilemma, just two months ahead of what Miliband has called the "make-or-break" UN summit in Copenhagen. The stakes could not be higher. The British ministers, moving on from Bangladesh to Delhi, emerged "optimistic" after successful talks with their Indian counterparts, particularly the new environment minister, Jairam Ramesh. On the same day, the Indians - assumed to be reluctant to commit to carbon cuts and hostile to US demands for them to do so - projected a modest level of carbon-dioxide emissions in 2031: between 2.8 and five tonnes per person. Current per capita emissions are estimated at 1.2 tonnes, well below the global average of four tonnes. India is now heading towards producing 20,000 megawatts of solar energy by 2020, and is skipping some of the usual steps towards industrialisation: in Kolkata, the ministers were shown the country's first ever housing complex run on solar power. Days later, hopes were raised further when another sticking-point country, Japan, announced that it would cut its emissions by 25 per cent on 1990 levels by 2020.
But Miliband, whose department is leading the way with a commitment to a 34 per cent reduction in the UK's emissions by 2020, warns against complacency. So does his brother David, the Foreign Secretary, who has been touring the EU presenting slideshows on the extreme potential results of global warming, and says that a deal "hangs in the balance". "There's a real danger the talks scheduled for December will not reach a positive outcome, and an equal danger in the run-up to Copenhagen that people don't wake up to the danger of failure until it's too late," the Foreign Secretary told reporters.
There is still a question mark over whether any proposed deal would be enough to make a difference. It has been agreed that the developed west must cut emissions by at least 40 per cent by 2020 to prevent a global warming increase of 2° or more. But campaigners warn that this may be too little, too late. The Committee on Climate Change has recommended that this target be increased to 42 per cent to ensure a 50-50 chance of preventing the rise. But as Tom Picken of Friends of the Earth asks: "Is this a morally acceptable level of risk?"
So, what would be the result of failure to reach an adequate deal when, according to Ed Miliband, there is "no plan B"? Campaigners have long emphasised how climate change hits the poorest hardest, even in Britain. A study by Oxfam and the New Economics Foundation think tank this year noted that the one in five Britons who live in poverty will be the most vulnerable to the impact of climate change. They will be the hardest hit by higher taxation on fossil fuels, the least able to afford adequate insurance against the effects of storm damage and flooding, and the most likely to lose out in the move away from carbon-producing jobs.
But it is the international imbalance that causes most concern. The Joseph Rowntree Foundation is the latest organisation to call for a long-term programme of work on climate change and social justice. "Rich countries got us into this mess and they have the money and the technology to get us out of it," says Jeremy Hobbs, executive director of Oxfam International. "This gives them a double duty to deliver major emission reductions at home and provide the money that poor countries need to start tackling their emissions, too." As the UN has warned: "[I]t is the poor, a constituency with no responsibility for the ecological debt we are running up, who face the immediate and most severe human costs."
This is not simply a western, liberal concern. As Rajendra Pachauri, the Indian chairman of the Intergovernmental Panel on Climate Change (who won a Nobel Prize along with the campaigning former US vice-president Al Gore) has said: "It's the poorest of the poor in the world, and this includes poor people even in prosperous societies, who are going to be the worst hit."
Now, in a letter to the UN secretary general, Ban Ki-Moon, the UK Foundation for Democracy and Sustainable Development has warned that unless governments step up efforts to tackle climate change immediately, the result could be significant incursions into what it calls "future democratic freedoms". The organisation's director, Halina Ward, says: "There is a real risk that as the decision-making implications of huge social challenges like climate change begin to bite, politicians will be tempted to tighten the reins on our democratic rights and limit our access to public decision-making on difficult issues." She adds: "We have to get climate change out of the environmental margins and into the social mainstream . . . The sooner we come to understand it as an issue of democracy and of social justice, the better."
Meanwhile, the spectre of natural disaster looms largest over poor countries. The total number of floods, cyclones and storms has quadrupled in the past two decades. Over the same period, the number of people affected by disasters has increased from roughly 174 million a year to more than 250 million on average. Environmental threat is acute in countries such as Bangladesh, where 119 million of the population subsist on less than $2 a day. For them and millions of others, talk of climate change is not a fad or fashion, a label to help "modernise" a political party, or the subject of dinner-party self-justification; it is literally a matter of life and death. For their sake, long-standing green campaigners and late-coming progressive converts alike must pray for a deal in December.