By Alex Kirby BBC News Online environment correspondent

The mountainous regions of the world are inexorably succumbing to the growing press of humanity, says a United Nations report.

Agriculture, building, war and climate change are all helping to tame what were once wildernesses.

The consequences for people who live in the mountains are likely to be severe.

For the first time we have a global snapshot of the threats and vulnerability of different mountain regions

Dr Mark Collins

As they play a crucial role in distributing water, the UN says, their future matters to us all.

A report published by the UN Environment Programme (Unep) says almost half of Africa's mountain regions are thought to have been appropriated for farming - 10% for crops, and 34% for grazing.

The regions whose mountains remain in their least damaged state are Greenland and north and central America.

The report, Mountain Watch, was compiled by the Unep World Conservation Monitoring Centre (Unep-WCMC). It will be given to delegates to the Global Mountain Summit to be held in Bishkek, the capital of Kyrgyzstan, next week.

Combining the data

The report is the first map-based assessment of environmental change in mountain areas and of the implications for sustainable development.

One person in two depends on mountain water (Image: T Natiano)

Dr Mark Collins, director of Unep-WCMC, said it graphically illustrated seven pressures or causes of environmental change: natural hazards, fire, climate change, infrastructure growth, violent conflict, changes in land cover, and agricultural intensification.

Maps showing ecosystems and species were overlaid with information about these different pressures, to identify conservation priorities.

Dr Collins said: "The results were stunning. We could clearly see which areas are suffering most from a combination of pressures or impacts.

"So for the first time we have a global snapshot of the threats and vulnerability of different mountain regions."

Dr Klaus Toepfer, Unep's executive director, said: "Mountains have often been seen as the homes of the gods. Legends abound, from the fabled yeti of the Himalayas to Bigfoot in the US.

Accelerating loss

"But this new report highlights how, like so many parts of the world, some of these last wild areas are fast disappearing in the face of agriculture, infrastructure development and other creeping impacts.

Norway's reindeer are being squeezed out (Image: Fred Grinberg)

"Behind all these is the spectre of climate change, which is already taking its toll on the glaciers and changing plant and animal communities in high altitude areas.

"These impacts and losses threaten the health and well-being of us all. Mountains are the water towers of the world."

The report says traditional agricultural systems, like terracing, can be good for mountainous areas, for example by helping to stabilise soils.

But much of the current conversion to farming is leading to loss of forests and other land cover, which can speed up erosion and soil loss.

'Neglect should end'

The report found:

• Parts of the Caucasus, California and the north-west Andes are among the most threatened and biodiversity-rich mountain areas in the world, and deserve priority for conservation
• Almost a quarter of mountain areas could be seriously affected by roads, mining and power, and pipelines by 2035
• Greenland's mountains are likely to be hardest hit by global warming, with 98% possibly seriously affected by 2055
• Africa's mountain regions are worst affected by multiple pressures.

Dr Andrei Iatsenia, Unep's mountain programme coordinator, said mountain environments covered about 24% of the world's land surface "and deserve the level of concern afforded to other global ecosystems".

All images courtesy and copyright of individual photographers/Unep/Topham