4.2 The Importance of pH
A few physical factors have a disproportionate effect on the distribution of organisms and the fact that humans play a large role in their modification means that their effects on the sustainability of ecosystems is rather important.
From "WATER"
http://www.unep.org/geo/geo4/report/04_Water.pdf
Rainwater and ocean acidification Acidity in rainwater is caused by the dissolution of atmospheric CO2, as well as by atmospheric transport and deposition of nitrogen and sulphur compounds (see Chapters 2 and 3). This is important because biological productivity is closely linked to acidity (see Chapter 3). The box on acidifying cycles in Chapter 3 describes some of the impacts of acid deposition on the world’s forests and lakes. The oceans have absorbed about half of the global CO2 emissions to the atmosphere over the past 200years (see Chapter 2), resulting in the increasing acidification of ocean waters (The Royal Society 2005). Acidification will continue, regardless of any immediate reduction in emissions. Additional acidification would take place if proposals to release industrially produced and compressed CO2 at or above the deep sea floor are put into practice (IPCC 2005). To date, injection of CO2 into seawater has been investigated only in small-scale laboratory experiments and models. Although the effects of increasing CO2 concentration on marine organisms would have ecosystem consequences, no controlledecosystem experiments have been performed in the deep ocean nor any environmental thresholds identified. The impacts of ocean acidification are speculative, but could be profound, constraining or even preventing the growth of marine animals such as corals and plankton. They could affect global food security via changes in ocean food webs, and, at the local scale, negatively affect the potential of coral reefs for dive tourism and for protecting coastlines against extreme wave events. It is presently unclear how species and ecosystems will adapt to sustained, elevated CO2 levels (IPCC 2005). Projections give reductions in average global surface ocean pH (acidity) values of between 0.14and 0.35units over the 21st century, adding to the present decrease of 0.1 units since pre-industrial times(IPCC 2007).
Managing water issues related to climate change Global-scale changes to the water environment associated with climate change include higher sea surface temperatures, disruption of global ocean currents, changes in regional and local precipitation patterns, and ocean acidification. These issues are typically addressed through global efforts, such as the UN Framework Convention on Climate Change and its Kyoto Protocol (see Chapter 2). Management at the global level involves numerous actions at regional, national and local scales. Many global conventions and treaties are implemented on this basis, with their effectiveness depending on the willingness of individual countries to contribute to their achievement. Because these changes are linked to other environmental issues (for example, land use and biodiversity), they must also be addressed by other binding or non-binding treaties and instruments (see Chapter 8). Major responses to the drivers of climate change – primarily the increased burning of fossil fuels for energy – are analysed in Chapter 2. These responses are generally at the international level, and require concerted action by governments over the long-term, involving legal and market- driven approaches. Focus is on responses to climate change-related impacts affecting the water environment that involve regulation, adaptation and restoration .