More than anywhere else on Earth, the polar regions are most affected by global warming. Yet it is exactly this threat to their existence that is attracting more tourists to the region than before.
The World Tourism Organisation puts the number of annual visitors to the Arctic, including Alaska, at more than one million. Although far fewer tourists visit Antarctica, the rate of there growth is causing as much concern to environmentalists.
This year 33,000 people will visit the Antarctic region, up from about 7,400 a decade ago, according to the International Association of Antarctic Tour Operators (IAATO), which promotes responsible tourism practices.
Great images from space
Dharavi stands on just a square mile of land - reckoned to be worth more than $10bn - and houses about 600,000 people in ramshackle buildings. The government will sell land below market prices and, as an incentive to create properties for the poor, says that for every square foot of accommodation created for slum dwellers, developers will get 1.3 square feet for commercial use. The argument is that while slum dwellers will get flats in high-rise blocks the rest of the land can be used for malls, middle-class apartment blocks and business parks. 
