The industrial revolution and its resultant technological society have led to the redistribution of compounds toxic to organisms and to the synthesis of substances previously unknown to nature. The result of these events has been a gradual, diffuse contamination of the entire planet. No region on Earth remains as clean as it did before these events. This unprecedented phenomenon is often referred to as the toxification of nature. For the first time in history, all of the Earth’s organisms are being subjected to complex mixtures of toxic substances, albeit at low-doses. The bioaccumulation and degradation of toxic compounds are highly dependent on temperature and radiation. Redistribution occurs primarily via the atmosphere. Climate change factors such as increases in temperature, and fluctuations in rainfall, cloud cover, windfall or distribution of dust, can also affect the mobility of pollutants. These processes are particularly important for contaminants that are transported over large distances by the atmosphere and subsequently enter the water cycle. This is especially true for hydrophobic contaminants that accumulate in soil and organisms. Water quality can therefore be compromised by the build up of pollutants during water storage and transport, and is thereby subject to the effects of climate change.

Metals, namely mercury, and persistent organic pollutants (POPs) are the toxic products for which environmental distribution is most influenced by climate. POPs were the subject of the Stockholm convention (22-23 May 2001), whereby member states agreed to reduce or eliminate their use and emission as well as promote research on their impact in the environment and human health. These compounds are known mutagens, carcinogens and teratogens, and are classified as 2A or 2B by the IARC (IARC, 1983). Natural distillation and condensation of POPs coupled with atmospheric transport have led to their accumulation in high-altitude ecosystems and organisms (Wania and Mackay, 1993). In the near future, the deposition patterns of POPs will most likely be under the influence of climate change as their retention in freshwater accumulation zones following atmospheric transport depends on local temperature (Carrera et al., 2002; Grimalt et al., 2001). Higher temperatures will cause greater emissions, as well as further melting of mountain ice, which will in turn increase the amount of pollutants leaked into water used for human consumption.