2014/07/16 Council Agenda Packet

21: NORTHWEST the need to maintain streamflows and water quality for fish and wildlife is balanced with human uses of water resources. In highly managed rivers, release of deeper, colder water from reservoirs could offer one of the few direct strategies to lower water temperatures downstream.47 Actions to improve stream habitat, including planting trees for shade, are being tested. Some species may be able to change behavior or take advantage of cold -water refuges.48 Key Message 2: Coastal Vulnerabilities In the coastal zone, the effects of sea level rise, erosion, inundation, threats to infrastructure and habitat, and increasing ocean acidity collectively pose a major threat to the region. With diverse landforms (such as beaches, rocky shorelines, bluffs, and estuaries), coastal and marine ecosystems, and human uses (such as rural communities, dense urban areas, international ports, and transportation), the Northwest coast will experience a wide range of climate impacts. Description of Observed and Projected Changes Global sea levels have risen about 8 inches since 1880 and are projected to rise another 1 to 4 feet by 2100 (Ch. 2: Our Changing Climate, Key Message 10). Many local and regional factors can modify the global trend, including vertical land movement, oceanic winds and circulation, sediment compaction, subterranean fluid withdrawal (such as groundwater and natural gas), and other geophysical factors such as the gravitational effects of major ice sheets and glaciers on regional ocean levels. Much of the Northwest coastline is rising due to a geophysical force known as "tectonic uplift," which raises the land surface. Because of this, apparent sea level rise is less than the currently observed global average. However, a major earthquake along the Cascadia subduction zone, expected within the next few hundred years, would immediately reverse centuries of uplift and, based on historical evidence, increase relative sea level 40 inches or more.4958 On the other hand, some Puget Sound as Projected Relative Sea Level Rise 2020 2040 rya Yew locations are currently experiencing subsidence (where land is sinking or settling) and could see the reverse effect, witnessing immediate uplift during a major earthquake and lowered relative sea levels."z Taking into account many of these factors and considering a wider range of emissions scenarios than are used in this assessment (Appendix 5: Scenarios and Models), a recent for the Latitude of Newport, Oregon Figure 21.3. Projected relative sea level rise for the latitude of Newport, Oregon (relative to the year 2000) is based on a broader suite of emissions scenarios (ranging from B1 to A1FI) and a more detailed and regionally -focused calculation than those generally used in this assessment (see Ch. 2: Our Changing Climate).5Q The blue area shows the range of relative sea level rise, and the black line shows the projection, which incorporates global and regional effects of 24 warming oceans, melting land ice, and vertical land movements.50 Given the difficulty of assigning likelihood to any one possible trajectory of sea level rise at this time, a reasonable risk assessment would consider multiple scenarios within the full range of possible outcomes shown, in conjunction with long- and short- term compounding effects, such as El Nino -related variability and storm surge. (Data from NRC 201250). U.S. GLOBAL CHANGE RESEARCH PROGRAM 492 CLIMATE CHANGE IMPACTS IN THE UNITED STATES