If climate change pushes sea levels higher, people in coastal areas in low-lying countries like Bangladesh could be forced from their homes. As part of the BBC's Planet Under Pressure series, Roland Buerk visits a family living in the Ganges River delta.
Most experts agree that global warming is a reality and that it will bring further rises in sea levels.
In the last century the world heated up by 0.6C, according to the International Panel on Climate Change (IPCC).
Sea levels rose by between 9 and 20cm and scientists predict further increases of 9 to 88cm by the year 2100.
The South Asian country of Bangladesh stands to be the worst affected.
It is situated in the low-lying Ganges River delta and is also one of the most densely populated countries on earth.
Char Bangla is one of thousands of islands in the mouths of the Ganges.
The land comes and goes with the tides and seasons as the silt is washed away and deposited by the river and sea.
The people who live on Char Bangla are among the most vulnerable anywhere to a rise in sea level.
"I have to work hard because of my misfortune," said Abdul Razzak. "There's lots of suffering here. Sometimes the tide is four or five feet high. Then I can't sleep because I have to stay standing up."
The villagers have built up platforms of mud for their straw huts to try to keep them out of the water.
They have planted trees hoping the roots will bind the soil to stop it being washed away.
But over the long term their efforts will almost certainly be in vain.
Millions of people in low-lying countries may be forced to migrate
Some estimate that the rise in sea level at the top end of the IPCC forecast is predicting will leave at least a fifth of Bangladesh under water.
And it is not just coastal areas that are under threat. Bangladesh's rivers are expected to flood even more frequently.
"It's a flat, flat, flat country," said Dr Atik Rahman of the Bangladesh Centre for Advanced Studies who has investigated how climate change will affect the country.
"The flow of water coming from the Himalayas - which is huge - depends on the differential of height.
"When the sea level is higher, the flow of that water will be restricted. So when you hear now of Bangladesh being a flood-prone country - it will be a much more flood-prone country in future."
Dr Rahman adds that after sea levels rise, salt in the ground water will become a major problem, with fields up to 40km from the new coastline rendered useless for growing crops.
The irony is that Bangladeshis have contributed little to the pollution blamed for enhancing climate change, and which threatens to bring so much destruction to their country.
Like most people here, Abdul Razzak's wife cooks on a wood-burning stove made out of clay.
But apart from that, the family consumes little energy.
They have no electricity and use candles for light. They get about by walking or in a boat powered by a single oar at the stern.
The people on Char Bangla are acutely aware that the "sins of the rich" could be visited on them.
"We are angry with the people who are doing this," said Abdul Razzak. "We are angry with the people building these factories that will make us sink into the sea."
"We have heard these kinds of things, the danger that is going to come. We are going to be washed away. But we are living by relying on Allah," said his wife Rabea Khatun.
Fields up to 40km from the new coastline will be rendered useless
"What can we do?", asked their neighbour Abdus Salaam Taluikdar. "We are angry but we're trying to get on with our lives. We can do nothing, but everyone is angry."
Dr Atik Rahman believes the richer countries have an obligation to help countries like Bangladesh which will suffer disproportionately from global warming.
"No contribution, highest impact - that makes it a huge case of moral inequality against which the global citizenry, the global nation states, must take action. If not we'll be calling it climatic genocide. That's where we're heading."
Some predict that in the future millions of people in low-lying countries like Bangladesh will be forced to migrate.
But a movement of people on that scale will create its own international tensions.
The world will have to learn to cope with refugees from climate change.