There are 10,000 policymakers, water experts, scientists, businessmen, researchers and writers from 130 countries here in the Mexican capital this week for the 4th World Water Forum.

On the agenda is everything from water privatisation, irrigation, integrated water resource management and even future wars over water. But even when the world's foremost water researchers and scientists meet, they are not discussing one of the biggest threats to the world's water resources: climate change.

Conspicuously absent from the official agenda in Mexico City are the problems of glacial retreat, melting icecaps, Himalayan flash-floods and the impact of melting permafrost on downstream irrigation and agriculture.

The fact that the polar and mountain regions of the world are melting like icecream cones is no more a matter of debate. It is happening right before people's eyes, and within less than a generation. With it there is climate variability all over the world, including this year's unprecedented winter drought in the Himalaya.

"One of the reasons experts don't want to talk about global warming and its impact is because the science is not consistent. But we don't need any more evidence, just study climate variability all over the world to understand that the climate is indeed changing," says Ainun Nishat from World Conservation Union (IUCN) Bangladesh. "The snowline is decreasing and the low flow of the Ganges and Brahmaputra is already a topic of debate and dispute between Nepal, India and Bangladesh."

Even though it is not on the agenda, the impact of global warming is being discussed in small, informal groups at the World Water Forum. The Third Assessment Report of the UN's expert group, the Inter-governmental Panel on Climate Change (IPCC) projects that the Earth's average surface temperature will rise between 1.4C-5.8C by 2100 if no major effort ismade to cut emissions of the greenhouse gases.

In the Nepal Himalaya average annual temperatures have been increasing 0.09C a year since the 1970s. At this rate, there could be a rise of as much as nine degrees by the end of the century, spelling a catastrophe for the mountains and the people who live below them. There are 2,315 glacial lakes within the country and 20 are already so swelled with melting snow that they are in imminent danger of bursting.

A Worldwide Fund for Nature (WWF) report released last year reported that 67 percent of Himalayan glaciers are retreating rapidly. The Fund was concerned about what this would mean to biodiversity and wildlife. But there is a much more serious issue: rapidly melting snows would increase the flow of Himalayan rivers in the dry season for the next 35 years, according to one simulation model, but after that the rivers would go dry. However, climate change is a global phenomenon caused by increased fossil fuel use in the insustrialised countries. The Nepal Himalaya may suffer the consequences, but the solutions lie elsewhere.

"Every year, countries like the US and Australia delay in making significant contributions towards climate change, we move closer to calamity," says Jamie Pittock, director of the WWF's Global Freshwater Program.

Others believe that instead of playing the blame game it is better to get together and ready for the worst. "We need to understand that climate is not going to stabilise soon, thus we need to work towards being prepared so that if there is a catastrophic event, there is minimum destruction," says Nishat. He proposes pressuring governments to work to develop early warning systems.

Himalayan experts agree that glacial retreat must be tackled at a regional level and are calling on cooperation of the affected countries. Biksham Gujja, policy adviser at WWF's Global Freshwater Program says: "Governments should work on adaptation strategy, take a proactive approach and work with the people.

IUCN's Nishat agrees. "Countries where the impact will be felt most need to seriously revise their national laws and incorporate climate change laws into them to avert future disasters."

Young and water wise

The 4th World Water Forum in Mexico City last week was sponsored by Coca Cola. But the fizzy drink wasn't what enticed children here.

Shanta Chaudhary, 14, of Dang and Suresh Baral, 13, of Kaski(pictured, above) made the trip to the Children's World Water Forum to talk about the role of young people in improving sanitation in Nepal. The two were chosen from among 400 Nepali schools with water and sanitation clubs. "When we started our youth club in my village with the help of UNICEF people didn't trust us so they shooed us away," remembers Shanta.

In 2004 only 35 percent of houses in Shanta's village had proper bathrooms but now over 60 percent do. "We don't just talk about latrines and bathrooms," the young girl explained confidently, "we perform street dramas, distribute fliers and have concerts on sanitation." It's now become a status symbol for people in her Dang village to have a bathroom, to keep surroundings clean and to live in a hygienic environment.

Suresh was involved in setting up his own school club in 2004 that offered loans of Rs 5,000 to families interested in building a bathroom. "Today, all the village's households are equipped," says Suresh proudly.

Participants in Mexico City were impressed with how much the children have achieved in so little time-something that adults would find impossible to do. Over 100 children aged 11-15, from 29 countries participated at the children's forum, presenting 55 local action plans five of which will be chosen to be presented at a dialogue session at the main water forum.

"The most important thing I learnt about water is that it is vital for sanitation and it is not wise to separate the two," Suresh told children from other parts of the world through an impressive powerpoint.

Living in dormitories, the children had a chance to meet other kids. Shanta and Suresh have made friends from Tajikistan, Laos, Mexico and Japan. They also learned from one another. Says Shanta: "There are many problems in our villages but that doesn't mean we wait for someone else to solve our problems. I am going back to Nepal with the message that children can make a difference."