North America

NORTH AMERICA

Here are highlights of the projected impacts of climate change on the North America region based on the Fourth Assessment Report of the IPCC (see first box on top right of screen).

Freshwater. Warming in western mountains is projected to cause decreased snowpack, more winter flooding, and reduced summer flows, exacerbating competition for over-allocated water resources.

Food. Moderate climate change in the early decades of the century is projected to increase aggregate yields of rain-fed agriculture by 5-20%, but with important variability among regions. Major challenges are projected for crops that are near the warm end of their suitable range or which depend on highly utilised water resources.

Human health. Cities that currently experience heatwaves are expected to be further challenged by an increased number, intensity and duration of heatwaves during the course of the century, with potential for adverse health impacts. Elderly populations are most at risk.

Forests. Disturbances from pests, diseases and fire are projected to have increasing impacts on forests, with an extended period of high fire risk and large increases in area burned.

Coastal populations. Coastal communities and habitats will be increasingly stressed by climate change impacts interacting with development and pollution. Population growth and the rising value of infrastructure in coastal areas increase vulnerability to climate variability and future climate change, with losses projected to increase if the intensity of tropical storms increases.

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A multiplier of complexity: Climate change adds challenges to managing the Columbia River system

Aerial view of Columbia River and Bonneville Dam. Photo: U.S. Army Corps of Engineers.

Managing water in the Columbia River basin involves balancing complex, often competing, demands for hydropower, navigation, flood control, irrigation, municipal uses, and maintenance of several populations of threatened and endangered species (e.g., salmon).

The river’s water supplies are already over-committed to meet current and projected needs. Water management in the basin operates in a complex institutional setting, involving two sovereign nations (Canada and the U.S. via the Columbia River Treaty), aboriginal populations with defined treaty rights, and numerous federal, state, provincial and local government agencies. Pollution is an important issue in many tributaries.

With climate change, projected annual Columbia River flow changes relatively little, but seasonal flows shift markedly toward larger winter and spring flows and smaller summer and autumn flows. These changes will coincide with increased water demand, mainly from regional growth but also induced by climate change— the higher the temperatures, the higher the demand. Loss of water availability in summer would exacerbate conflicts, already apparent in low-flow years, over water. Climate change is also projected to impact urban water supplies within the basin. Long-lead climate forecasts are increasingly considered in the management of the river, but in a limited way. Reaching operating goals and keeping “reliability” levels buoyant are expected to become increasingly difficult under these circumstances.

More details and citations may be found here: Climate change adds challenges to managing the Columbia River system.

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Individual countries in North America

For more detailed analysis of the climate change related vulnerabilities of each country in the North American region, click on the following. These links will take you to the country pages of the Adaptation Learning Mechanism. The information is sourced from country assessments and other external sources.

North America

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