By Khalid Malik

Today marks World Water Day - time for deep concern as an adequate water supply is one the most pressing challenges facing the world. As the Himalayan glaciers melt due to climate change, China is one of the countries most vulnerable to the drying up of its water supply.

Without access to clean and adequate supplies of fresh water, communities will be unable to improve agriculture-based livelihoods or improve health conditions.

Yet increasing demands by industrial and urban users and increasing levels of pollution are creating serious shortages of clean and adequate water supplies for countries around the world.

Exacerbated water supply challenges are the emerging consequences of global climate change. As highlighted in the initial findings of this year's Inter-Governmental Panel on Climate Change (IPCC), there is now clear and convincing evidence that emissions of greenhouse gases are wreaking havoc on the planet's life support systems with far reaching implications for humankind.

Ten of the warmest years in recorded history have occurred since 1990, coupled with increasing frequency of extreme weather events and rapid rates of melting of the world's glaciers and ice caps.

The time for speculation and debate over climate change is over. We are now entering a period of consequences. In Asia, a particular concern is the retreat of the Himalayan glaciers, threatening to alter water supply to hundreds of millions of people in the region.

A major UN concern, Millennium Development Goal 7 places top priority on actions to improve water security as a critical condition to achieve the overarching goal of eliminating extreme poverty.

Developing countries have achieved many hard-won economic gains over the past decades. However, the melting of the Himalayan glaciers poses serious risks to sustaining any such gains in the decades to come. The poor will feel the impact the hardest, since they are the communities that lack the capacity to adapt to this uncertain future.

The Himalayas are known as the water tower of Asia. They are the largest location of glaciers and fresh water apart from the polar ice caps. These glaciers feed seven of the great rivers of Asia, the region's lifeblood for water security the Yangtze, Mekong, Yellow, Ganges, Indus, Brahmaputra, Salween rivers.

However, these glaciers are receding faster than any other glaciers on the planet. Some estimates predict that they could completely disappear by mid-century. This would result in the eventual drying up of water supplies.

Climate change is expected to bring significant changes to local land and water use over the next decades. This includes changes in the seasonal supply of water as the rate of glacial melting escalates. The glacial area has shrunk by 20 percent over the past century. This brings risks and uncertainty for the predictability of water flows and affects long-term development policies in the region.

Trends in glacial melting are particularly important for water supply challenges in China. From faster rates of glacial melting in the west to serious land degradation in the north, significant threats exist for China's rural population of 800 million, the world's largest.

With per capita water availability already only a quarter of the world's average, half the country is already experiencing significant land degradation pressures. Future glacial melting could impact water supplies and constrain the ability of communities to sustain their hard won development achievements.

As highlighted in China's first National Assessment Report on Climate Change, released at the end of last year, few aspects of development will be immune from the emerging impacts of climate change in China.

Rising temperatures and melting trends could exacerbate water security and cause long-term drops in agricultural output. The changing water flows could threaten the Yangtze and Yellow rivers which form the basis for much of China's economic growth and social development.

The impact of temperature change in China will be most marked on populations in the west. They have the most limited adaptive capacity, with communities living in areas with agriculture reliant on rainfall, prone to droughts or floods.

With the impact of climate change already being felt, adaptation through enhanced resilience is a top priority. Unfortunately, in most cases adaptation has yet to be given the prominence it merits in local debates on sustaining development and reducing poverty.

How to reach the poorest and most vulnerable communities remains a major concern. The big challenge is the development and implementation of provincial adaptation strategies and actions.

While national policies have been enacted in recent years to mitigate and adapt to climate change, much work is needed to translate these policies into on-the-ground action for results.

The scale of possible future impacts varies both between and within provinces. If measures are to have real effect in coming years, an urgent need exists to develop local policies, partnerships and implementation capacities.

Based on the principles in the UN Framework Convention on Climate Change and strong cooperation with China's National Climate Change Coordination Office and partners, the UN is working closely with Chinese institutions to help provide assistance to government, business and society to integrate Adaptation Policy Frameworks into local development policies and actions.

The author is UN resident coordinator and UNDP resident representative in China.

(China Daily March 22, 2007)