Over the past 100 years, the changing global climate has shrunk the glaciers on Mt. Hood by more than one-third. But melting ice on Portlandís mountain icon is just the most visible of the impacts of global warming. The changing climate will impact Portland's future broadly and deeply. It means dramatic changes here in Portland and the foundations of the Northwest: our forests, rivers, fish, farms and coast.

Since 1900 the Pacific Northwest has warmed by 1.5° F. In the next century, the warming is expected to accelerate and increase by about 1° F every 10 years (University of Washington Climate Impacts Group - http://www.cses.washington.edu/cig/). The last time this region's climate changed so dramatically was the Ice Age, when glacial ice sheets covered much of the Northwest. This time, fueled by vast quantities of human-caused carbon pollution, the climate is changing much faster.

Scientists expect that the Northwest will experience more warming in summer than in winter, and nights will cool off less than they do today. In addition, increased urbanization, population growth and related roads and rooftops will exacerbate the urban heat island, increasing temperatures even more.

Changes in the water cycle are equally important, with winters expected to be wetter and summers drier. This, coupled with higher temperatures, may mean higher streamflows in the spring, when water is already abundant, and lower flows in the summer, when surface water flows are badly needed for irrigation, drinking water, hydropower and salmon. The trend will be toward increased use and reliance on groundwater sources.

Forests, a cornerstone of Portlandís economy and environment, are particularly vulnerable to climate change. The greatest threats to forest health include drought, fire, pests, and disease, and climate change is expected to increase all of these. Oregonís beaches, too, are threatened by rising sea levels and stronger storms, and coastal flooding and erosion will increase.

Portland will also experience significant changes as a result of the response to global warming. Fortunately, many of the local solutions to climate change offer substantial community benefits and can provide jobs as well as improve personal health. Reducing use of the fossil fuels that cause climate change Ė primarily gasoline, diesel, natural gas and electricity from coal and natural gas Ė also reduces the economic drain of paying for these fuels and improves the bottom line for businesses and for household budgets. Renewable energy resources like wind and solar power offer tremendous economic development potential, and strategies like adding insulation and upgrading windows simply make good economic sense. On the transportation front, increasing walking, bicycling and transit use has the added benefit of improving personal health and air quality, while keeping dollars in the local economy.

Climate change presents enormous challenges, both globally and here in Portland. However, Portland is an innovator in developing solutions and was the first city in the United States to adopt a climate-protection plan almost 15 years ago. As the world mobilizes to respond to climate change, Portland is positioned to lead the way in minimizing carbon emissions, reducing the disruptions caused by global climate change and making our community healthier, stronger and more vibrant.

 

 

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Mt. Hood August 1984 (top) and late summer 2003 (bottom). Photos ©Gary Braasch From his book: Earth Under Fire; How Global Warming is Changing the World (University of California Press, September 2007).



Click Here to view a chart depicting 400,000 years of atmospheric carbon dioxide concentration and temperature change.


Click Here to view a chart depicting the greenhouse gas emissions trend since 1990.

 

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