The Need to Assess Impacts of Climate Change on Water Quality
There is an emerging need to assess the impacts of climate change on environmental water quality. 

The Intergovernmental Panel on Climate Change (IPCC) last week concluded in the first volume of its fourth assessment report that major advances in climate modelling and the collection and analysis of data now give scientists "very high confidence" (at least a 9 out of 10 chance of being correct) in their understanding of how human activities are causing the world to warm.  The report states that if atmospheric concentrations of greenhouse gases double compared to pre-industrial levels, this would "likely" cause an average warming of around 3°C (5.4°F), with a range of 2 - 4.5°C (3.6 - 8.1°F).

Because of increasing concerns about water quality for human use and ecosystem sustainability, there is an emerging need to assess the impacts of climate change on the quality of inland water resources on a global scale.  Richard Robarts, the Director of UNEP's GEMS/Water Programme points out, "Our Programme is well positioned to carry out a parallel assessment on climate change and water quality, and can make a valuable contribution to measuring the achievement of the Millennium Development Goals." 

This observation follows on the heels of the recent launch of a new publication, Water Quality for Ecosystem and Human Health.  This report from GEMS/Water indicates that climate change could affect water quality in a number of ways.  While some effects may be beneficial, others may be detrimental to both aquatic ecosystems and to human well-being.

Although the heat-trapping property of greenhouse gases is undisputed, there is uncertainty regarding exactly how the Earth's climate responds to them and whether or not these are part of the cause of increases in surface temperatures around the globe.

Increased temperatures could change the boundaries between the ranges of cool and cold-water organisms increasing the risk of extinction of sensitive species. Warmer water will decrease the saturation of dissolved oxygen (DO), increasing the likelihood of anoxia. As well, warmer temperatures will increase the decomposition rate of organic material, and decrease levels of oxygen in the water column.

Higher temperatures may reduce ice cover and alter stratification and water column mixing in lakes, key events that influence the nutrient balance of these systems. The cumulative effects of anthropogenic activities such as increased nutrient concentrations (from agriculture and urbanization) coupled with warmer water temperatures could accelerate biological productivity, increase plant biomass, and the frequency of events such as algal blooms that can be toxic.

In areas with more frequent and intense precipitation, more contaminants and sediments will be flushed into lakes, wetlands and rivers, degrading water quality and exacerbating non-point source pollution from agricultural and urban sources.  However, in some areas, these higher flows could dilute pollutants and actually improve water quality.  Further, increased flooding associated with more frequent and intense precipitation could damage or overwhelm municipal treatment facilities, mine tailing ponds, or land-fills, and increase the risk of contamination. Areas of standing water could provide breeding grounds for insect and microbial pathogens, increasing the risk of disease. In regions that undergo periods of drought or receive lower than average annual rainfall, lower river flows will concentrate pollutants and increase salinity, as the dilution effects of watercourses will be reduced.

This evidence points to the strong need to undertake global monitoring and assessment of the impacts of climate change on the inland water environment. 

Water Quality for Ecosystem and Human Health is available in English in PDF and "Digital Atlas" formats at http://www.gemswater.org/publications/index-e.html and at http://www.gemswater.org/freshwater_assessments/index-e.html.

What does GEMS/Water do?
Since its establishment in 1978, UNEP's Global Environmental Monitoring System (GEMS) Water Programme has become the primary source for global environmental water quality data. It is a multi-faceted water science centre oriented towards knowledge development on inland quality issues throughout the world.  Major activities include monitoring, assessment and capacity building.

The twin goals of the programme are to improve water quality monitoring and assessment capabilities in participating countries, and to determine the status and trends of regional and global water quality.  These goals are implemented through the online GEMStat database, at www.gemstat.org, including water quality data and information from more than 100 countries, with over 2,800 stations, two million entries for lake, reservoir, wetland, river and groundwater systems. By compiling a global database, GEMS/Water adds value to country-level data by making possible global and regional water quality assessments.

The programme also carries out evaluations on a range of water quality issues and methodologies. GEMS/Water data have been used by other organizations, including the UN system and universities around the world.

For more information about GEMS/Water, contact: Dr. Richard D. Robarts, Director, tel: +1-306-975-6047 fax: +1-306-975-5143 e-mail: richard.robarts@gemswater.org or visit www.gemswater.org