Climate Change: Water Impacts

Climate change will seriously affect water resources around the world. Changing water levels, temperatures and flow will in turn affect food supply, health, industry, transportation, and ecosystem integrity.

Ontario’s quarter-million lakes and countless rivers and streams hold about one-third of the world’s fresh water. The province’s 11 million people rely on these waters, as well as on groundwater and rainfall, for drinking, agriculture, and industrial uses. Forty-five percent of Quebec residents take their water from the St. Lawrence River, which flows from the Great Lakes. Projected changes in rainfall, evaporation, and groundwater recharge rates will affect all freshwater users.

• Lake levels are expected to decline in both inland lakes and Ontario’s four Great Lakes, as more moisture evaporates due to warmer temperatures and less ice cover.
• Reduced summer water levels are likely to diminish the recharge of groundwater, cause small streams to dry up, and reduce the area of wetlands, resulting in poorer water quality and less wildlife habitat.
• Climate change will also mean an increase in the frequency and severity of droughts and flooding.

Glaciers

Glacial melting is one of the most striking and visual signs of the impacts of climate change. During the last century, the southern Canadian Rockies have shown remarkable loss in glacial cover.

In B.C.’s Glacier National Park, scientists believe more than 50 per cent of the glacier ice has melted away in the last century – enough melted ice to fill a reservoir at least five kilometres tall by five kilometres wide.

• Fact: Scientists estimate that globally glaciers are losing 92 cubic kilometres of ice per year – that’s as much water used by Canada’s homes, farms and factories over six years.

Glaciers store snow like bank accounts store money – they hold snow in the winter and release water when it’s most needed, during hot dry summers and periods of drought. However, global warming is cashing in on a bank account that has been built over thousands of years but isn’t being replenished.

Annual water flows from glaciers are diminishing, as less ice remains every year. Late summer flows of the Mistaya River in Banff National Park have decreased 39 per cent over the last 50 years alone. Experts say that communities as far as 3,000 kilometres from the mountains – such as those on Hudson Bay – will be affected in the decades to come if warming continues.

See an interactive map on water resource impacts in North America

Reprinted with permission from the David Suzuki Foundation.