Changing World

While the effect of human activity on the global climate is hotly debated, physical signs of environmental change are all around us.

Some scientists say an increase in the rate of melting of the world's glaciers is evidence of global warming.

Argentina's Upsala Glacier was once the biggest in South America, but it is now disappearing at a rate of 200 metres per year.

Other scientists say its reduction is due to complicated shifts in glacial dynamics and local geology.