Climate Impacts in the Northwest | Climate Change Impacts | US EPA

Key Points

• Warming temperatures and declines in snowpack and streamflow have been observed in the Northwest in recent decades.
• Climate change will likely result in continued reductions in snowpack and lower summer streamflows, worsening the existing competition for water.
• Higher temperatures, changing streamflows, and an increase in pests, disease, and wildfire will threaten forests, agriculture, and salmon populations.
• Sea level rise is projected to increase erosion of coastlines, escalating infrastructure and ecosystem risks.

Overview

The Northwest is best known for its huge Pacific coastline and showery weather. The region is home to the Cascade Mountain Range that runs north-south through Washington and Oregon, resulting in large climatic differences on the western and eastern sides of the scope. West of the mountains, year-round temperatures are mild, winters are wet, and summers are dry. East of the mountains, it is typically sunnier and drier throughout the year, winters are cold, and summers can be significantly hotter. [ 1 ]
Over the last century, the average annual temperature in the Northwest has risen by about 1.3°F. [ 2 ] Temperatures are projected to increase by approximately 3°F to 10°F by the end of the hundred, with the largest increases expected in the summer. [ 2 ] precipitation in the region has seen a decline in both the come of entire snow and the proportion of precipitation falling as snow. Declines in snowpack and streamflows have been observed in the Cascades in late decades. In Washington state, phonograph record low snowpack values were measured in April 2015 and in seventy-four percentage of long-run monitoring stations. [ 3 ] Changes in average annual precipitation in the Northwest are probably to vary over the century. Summer precipitation is projected to decline by a a lot as 30 %, with less frequent but heavier downpours. [ 2 ]
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Impacts on Water Resources

A dependable provision of water is crucial for energy product, department of agriculture, and ecosystems. much of the Northwest ‘s water is stored naturally in winter snowpack in the mountains. The snowpack melts and replenishes streams and rivers in the late spring and summer, when there is very little rain. Climate switch threatens this natural repositing by changing the time of snowmelt and the measure of urine available in streams and rivers ( streamflow ) throughout the year. [ 2 ] Warmer springs contribute to earlier mellow of the snowpack, higher streamflows in former winter and early spring, and lower flows in summer. leap snowmelt is projected to occur three to four weeks earlier by mid-century and summer streamflows are probably to decline. [ 2 ] In the Cascade Mountains, measurements of snowpack taken on April 1 ( when snowpack is normally at its flower ) have decreased by about 20 % since the 1950s. [ 2 ]

Climate change can besides lead to changes in the type of precipitation. Warmer winters cause more precipitation to fall arsenic rain alternatively of snow, peculiarly at lower elevations. This reduces dirty moisture, snow collection, and the sum of water system available from snowmelt. [ 2 ] [ 4 ] Further, increased deluge risks around rivers that receive waters from both winter rains and peak runoff in late spring are expected. [ 2 ]
Changing streamflows are probably to strain water system management and worsen existing contest for water. Competing demands for urine presently include hydropower, agrarian irrigation, municipal and industrial uses, and protection of ecosystems and threatened or endangered species. Increasing temperatures and populations could deepen demand and far stress urban water supplies that are already at risk of diminishing because of climate change. [ 2 ]
Forty percentage of the nation ‘s hydropower is generated in the Northwest. [ 2 ] Lower streamflows will likely reduce hydroelectric supply and could lead to large economic losses in the region. Reduced streamflows combined with rising temperatures and a growing population are raising concerns about the ability to meet increased air condition and other electricity demands. [ 2 ]
For more information on climate change impacts, please visit the Water Resources Impacts or the Energy Impacts pages .
Natural surface water handiness during late summer is projected to decline across most of the Northwest. This map shows expected changes in local overflow ( shading ) and streamflow ( color circles ) for the 2040s ( compared to the period 1915 to 2006 ), assuming that heat-trapping greenhouse gases will be reduced in the future. source : USGCRP 2014 [ 6 ]

Click the prototype to view a larger version .
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Impacts on Coastal Resources

Climate exchange is damaging the Northwest coastline. Projections indicate an increase of 1 to 4 feet of global sea level raise by the end of the century, which may have implications for the 140,000 acres of the region that lie within 3.3 feet of eminent tide. [ 2 ] Sea level rise and storm scend pose a gamble to people, infrastructure, and ecosystems, specially in low lying areas, which include Puget Sound. Warming waters and ocean acidification threaten economically significant marine species and coastal ecosystems. [ 2 ] Many areas of Seattle are projected to fall below ocean level during high tide by the end of the hundred. Shaded blue areas depict three levels of sea floor lift, assuming no adaptation. The high ( 50 inches ) and medium ( 13 inches ) estimates are within the range of stream projections, while the highest level ( 88 inches ) includes the consequence of storm surge. source : USGCRP 2014 [ 6 ]
Flooding, seawater flood, and corrosion are expected to threaten coastal infrastructure, including properties, highways, railways, effluent discussion plants, stormwater outfalls, and ferry terminals. Coastal wetlands, tidal flats, and beaches are probable to erode or be lost as a result of seawater flood, which heightens the vulnerability of coastal infrastructure to coastal storms .
Some coastal habitats may disappear if organisms are ineffective to migrate inland because of topography or human infrastructure. This is expected to affect shorebirds and humble eatage fish, among other species. Warmer waters in regional estuaries, including Puget Sound, may contribute to an addition in harmful algal blooms, which could result in beach closures and declines in amateur mollusk harvests. Ocean acidification is besides expected to negatively impact important economic species, including oysters and Pacific salmon .
For more information on climate change impacts on coastal resources, please visit the Coastal Resources foliate .
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Impacts on Ecosystems and Agriculture

Higher temperatures, changing streamflows, and increases in pests and disease endanger forests, agriculture, and pisces populations in the Northwest. [ 2 ]

Forests make up closely half of the Northwest landscape. These areas provide crucial habitat for pisces and wildlife and support local economies, refreshment, and traditional tribal activities. [ 2 ] Forests have become warm and dry due to rising temperatures, changes in precipitation, and reduce soil moisture. These stresses make trees more susceptible to insect outbreaks and disease and make forests highly flammable. An addition in the total and size of wildfires has been observed in the region in holocene decades. [ 2 ] These impacts are expected to worsen in the future, resulting in larger areas burned each class and expanded outspread of pests, including the batch ache beetle. Some types of forests and other ecosystems at high elevations are besides expected to disappear from the region by the end of the hundred from inability to survive changing climatic conditions. [ 2 ] These changes are likely to have meaning effects on local anesthetic lumber revenues and bioenergy markets .
Under hot, drier conditions, insects and fire can have large accumulative impacts on forests. This is expected to be the dominant driver of forest change in the near future. The top map shows areas burned between 1984 and 2008 or affected by insects or disease between 1997 and 2008. The penetrate map indicates the have a bun in the oven increase in area burned resulting from a 2.2°F heating in average temperature. source : USGCRP 2014 [ 6 ]

Click the persona to view a larger version.Commercial fish and mollusk harvested in the Northwest were valued at $ 480 million in 2011. [ 2 ] Warming waters have already contributed to earlier migration of sockeye salmon in some streams and earlier increase of algal blooms in some lakes. Warmer waters are likely to increase spring and summer disease and mortality in Chinook and sockeye salmon in some river basins. Species that spend all or part of their lives in rivers, including salmon, steelhead, and trout, will suffer from decreased summer flows and increased flood and winter flows. Projections suggest that suitable habitat for the four trout species in the region will decline by an median of 47 % near the end of this century, compared to past decades. [ 2 ]
Ocean acidification is besides expected to negatively impact mollusk, including oysters, and others species, including Pacific salmon, resulting in economic and cultural implications. Warmer coastal waters may alter migratory patterns and areas of desirable habitat for marine species, resulting in changes in abundances .
farming is an authoritative economic and cultural component in rural areas of the Northwest. In the short-run, a longer growing temper and higher levels of atmospheric carbon dioxide may be beneficial to crops. [ 2 ] In the longer-term, boil down water handiness for irrigation, higher temperatures, and changes in pests, diseases, and weeds may harm crop yields .

Threatened Salmon Populations

Salmon swim upstream. credit : uracil Fish and Wildlife Service Human activities already threaten Northwest salmon populations. These activities include dam construct, logging, befoulment, and overfishing. Climate change impacts far stress these salmon populations. Salmon are particularly sensitive due to their seasonally timed migration upstream to breed. Higher winter streamflows and earlier vertex steamflows due to climate change will damage spawning nests, wash away incubating eggs, and coerce young salmon from rivers prematurely. Lower summer streamflows and affectionate stream and ocean temperatures are less favorable for salmon and other cold-water fish species. These climate change impacts facilitate the ranch of salmon diseases and parasites. many salmon species are already considered threatened or endangered under the Federal Endangered Species Act. Studies show that by 2100, one third of current habitat for Northwest salmon and other coldwater fish will be besides quick for these species to tolerate. [ 5 ]
For more data on climate change impacts on forests, please visit the Forests Impacts page .
For more information on climate change impacts on agriculture and food provision, please visit the Agriculture and Food Supply Impacts page .
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References

[ 1 ] U.S. Fish and Wildlife Service ( 2011 ). Climate Change in the Pacific Northwest .
[ 2 ] USGCRP ( 2014 ) Mote, P., A. K. Snover, S. Capalbo, S. D. Eigenbrode, P. Glick, J. Littell, R. Raymondi, and S. Reeder, 2014 : Ch. 21 : Northwest. Climate Change Impacts in the United States : The Third National Climate Assessment, J. M. Melillo, Terese ( T.C. ) richmond, and G. W. Yohe, Eds., U.S. Global Change Research Program, 487-513 .
[ 3 ] U.S. Department of Agriculture. Natural Resources Conservation Service, Washington. Accessed June 1, 2015 .
[ 4 ] US EPA ( 2016 ). Climate Change Indicators in the United States : Trends in April Snowpack in the Western United States, 1955-2016.

[ 5 ] USGCRP ( 2009 ). global Climate Change Impacts in the United States. Karl, T.R., J. M. Melillo, and T. C. Peterson ( eds. ). United States Global Change Research Program. Cambridge University Press, New York, NY, USA .

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