North America Facing Costly Water Shortages From Climate Change, International Panel Concludes

Escalating tensions between water users are among the key challenges facing North America, according to the Intergovernmental Panel on Climate Change (IPCC).

Many water resources across North America are already heavily used by industry and agriculture, as well as for drinking water and hydropower, the panel states. Shifts in rainfall patterns, melting mountain glaciers, rising temperatures, increased demand and reduced supplies in some places are likely to aggravate the situation unless cuts are made in greenhouse gases to reduce the scale and pace of climate change.

A report released by IPCC on April 6, notes that while North America has "considerable adaptive capacity, actual practices have not always protected people and property from adverse impacts of climate variability and extreme weather events."

Some of the challenges facing North America in terms of adaptation include a lack of information on climate change and its likely local impacts and financial barriers.

"Canada and the United States are, despite being strong economies with the financial power to cope, facing many of the same impacts that are projected for the rest of the world," said Achim Steiner, executive director of the UN Environment Programme (UNEP) which co-founded the IPCC.

The fourth report of IPCC Working Group II states that heavily-used water systems of the western United States and Canada, such as the Columbia River, that rely on capturing snowmelt runoff will be especially vulnerable. A 2-degree-Celsius warming by the 2040s is likely to lead to sharply reduced summer flows coinciding with sharply rising demand.

The report estimates that Portland, Ore., will by then require more than 26 million additional cubic meters of water as a result of climate change and population growth. This will coincide with a fall in summer supplies from the Columbia River by an estimated 5 million cubic meters.

Meanwhile, just more than 40 percent of the supply to southern California is likely to be vulnerable by 2020. Global warming is exptected to trigger losses of the Sierra Nevada and Colorado River basin snow pack.

The report also states that lower levels in the Great Lakes are likely to influence many sectors. Adapting infrastructure and dredging would entail a range of costs. This is likely to exacerbate controversies linked with water diversions to cities such as Chicago and the competing demands of water quality, lake-based transport and drought mitigation. Additionally, summer temperatures in midwestern and southern lakes and reservoirs could exceed 30 degrees Celsius.

Levels of phosphorus, a nutrient from such sources as sewage and detergents, are likely to rise in some bays in the Great Lakes by as much as 98 percent.

Other vulnerable supplies include Ogalla Aquifer -- a shallow formation that underlies South Dakota, Nebraska, Wyoming, Colorado, Kansas, Oklahoma, New Mexico and Texas. Here a 2.5-degree-Celsius temperature rise or more could reduce natural re-charge of the aquifer by over a fifth.

The Working Group II report of the Fourth Assessment of the Intergovernmental Panel on Climate Change can be found at http://www.ipcc.ch or www.unep.org.

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