Adapting to Climate Change (Third in a series)

*Note to readers: As CERF’s biennial conference in Portland, Oregon draws near, we take a closer look at how one state in the Pacific Northwest – Oregon – is adapting to the implications of climate change in this article, the third in a series about Pacific Northwest estuaries. The last article, “Diversity of Northwest Estuaries,” (CERF February 2009 Newsletter) described the variety of habitats, species and functions of estuaries ranging from Humboldt Bay, California, to Fraser River, British Columbia. The first article, “Pacific Northwest Estuaries Were Born of Fire and Ice,” (CERF October 2008 Newsletter) described the physical setting of northwest estuaries.
      A final article will consider some ways in which Pacific Northwest estuaries may provide indicators for other regions.
      The series of articles is coordinated by John Bragg, coastal training coordinator for the South Slough National Estuarine Research Reserve in Charleston, Oregon.

The people living on the western edge of North America have always needed to be ready to adapt to dramatic displays of nature’s power. The forces that shape the Pacific Northwest coast include both sudden, spectacular events – such as earthquakes that occur at a juncture of crustal plates a few hundred miles west, rattling windows and walls from California to Washington and occasionally lashing the coast with their resultant tsunamis – and more gradual processes, like the slow uplift or subsidence of the coastal margin, as well as seasonal storms. The storms driven out of the Pacific Ocean each winter bring waves, currents, tides, and winds that cause erosion, landslides, and flooding. The storms come with enough force to sever power and communication lines, or wash out bridges and highways. The storms can leave entire communities isolated for days at a time.

      Given the predictions for some initial effects of climate change – even-fiercer winter storms, sea level rise, and the subsequent loss of habitats and infrastructure – these kinds of hardships can be expected to intensify as the climate warms. With its potential to disrupt both economies and ecosystems, climate change represents a challenge of such magnitude as to rank alongside of earthquakes, tsunamis and other devastating events that have shaped the Pacific Northwest. In an era of global warming, tried-and-true methods of planning may not work; climate change involves too many unknowns to be able to know for sure. There is a growing sense of urgency that communities and governments must begin to act now to ameliorate at least some of the effects that climate change is bound to cause.

      While in the scientific community there’s long been little doubt that climate change is real, it’s only in the last several years that a majority of the public, including political leaders and decision-makers, have come to share their view. The transformation coincided with the 2004 release of two reports on ocean health by the Pew Oceans Commission and U.S. Commission on Ocean Policy. Members of those commissions now collaborate as the Joint Ocean Commission Initiative (JOCI) to speed development of meaningful ocean policy. In an April 2009 report to President Barack Obama detailing steps that can be taken to address climate change, the joint commission encouraged the President and Congress to recognize the contributions coastal areas make to national well-being. Many problems facing the coasts stem from “a fundamental mismatch between the way natural systems work and the way we manage the activities that affect them,” the commissioners wrote. “Unfortunately, the lack of a rational management strategy and a substantially weakened ocean science enterprise have resulted in sharp declines of the valuable goods and services that our oceans, coasts, and Great Lakes have traditionally provided.” (JOCI, 2009.) (See box: The Value of Healthy Coasts and Oceans.)

      With little evidence that concerns about sea level rise have slowed the movement of population toward the coasts, some Pacific Northwest coastal communities may find themselves having to accommodate both rising seas and rising demands for land to develop. Yet time-tested methods for community planning and development may fall short since adapting to climate change carries risks both known and unknown. Planners will need greater flexibility to adapt their management methods and modify their goals as the risks of climate change become better defined. Adaptive climate strategies will allow coastal managers to find ways to reduce risk, ensure that coastal communities remain environmentally and culturally viable, and reduce the vulnerability of coastal ecosystems to rapid change.

      Current estimates call for an increase in sea level of about 56cm by 2050 and 127cm by 2100 in the Pacific Northwest. Increases of that magnitude will significantly increase the heights of tides in estuaries. The geophysical setting of northwest coasts and estuaries makes them particularly vulnerable to rising sea level. Individual estuaries will respond differently to climate change and sea level rise, based on differences in their sedimentation rates, their shorelines and the pace of sea level rise. Any sustained alteration of those factors will change the shape and productivity of the estuary. (Oregon Coastal Management Program, 2009.)

      Many of Oregon’s estuaries are defined by sand spits that only provide a thin margin of protection against ocean forces. As sea level rises, the spits will move in response to changing storm patterns, or even breach (as happened to the Tillamook spit in 1952 and nearly happened to the Netarts spit in 2007). Most of Oregon’s estuaries are also limited on the landward side by dikes and levees, or steep hills. Behind many dikes are the coastal cities, built on filled estuarine lands and exposed to the risks posed by the rising waters. As sea level rises, tide water will propagate into the upper, freshwater extents of the estuaries. There will be little room for the freshwater and tidal marshes to migrate. Some freshwater marshes will vanish altogether, and small habitats or niche communities that occupy the fringes of the marshes will be lost.

      Sea level increase will affect different sections of the northwest coast differently. On the southern Oregon coast, tectonic forces are lifting the shoreline at a rate that is keeping up with the current rate of sea level rise. On the northern Oregon coast, the shoreline is subsiding. Such differences will drastically affect how and to what degree cities, homeowners, businesses, dairy farms, shopping centers and industrial areas will be affected.

      In 2007, faced with a daunting array of potential effects from climate change, 19 local and state elected officials from California, Oregon and Washington wrote to the joint commission asking what steps state and local governments could take to begin preparing for climate change. In January 2009 the joint commission recommended a number of actions communities can take. (See box: Protecting West Coast Communities.) Commissioners recommended communities consider climate change in every program and policy and begin protecting both infrastructure and natural systems that are showing signs of climate-related stress. (JOCI, 2009)

    The U.S. Environmental Protection Agency has identified significant changes that estuaries may have to adapt to, including:

• erosion and changes in water quality along ocean and estuarine shores,
• altered tidal ranges and salinity gradients in wetlands; loss of coastal margins, beaches, mudflats, marshes and other wetland habitats,
• increased depth and salinity in open estuarine waters,
• inundation or landward migration of marsh habitats (with loss of native plants, birds, invertebrates, and fish),
• changes in the structure or function of habitats,
• loss of critical, foundational species,
• loss of sunlight to submerged aquatic vegetation.

    Some of these changes are of particular concern in Pacific northwest estuaries. For example, increases in water temperatures beyond a critical limit will adversely affect fish, particularly salmon. Reduced oxygen, increased algae blooms, changes in the microbial processes that affect water quality, and the occurrence of oxygen-poor dead zones offshore or at the mouths of some rivers are likely to lead to declines in native species. Climate change may be already affecting the upwelling of nutrient-rich ocean waters, which is the physical basis for the marine food web. (OCMP, 2009.)

    Some effects of climate change are already becoming visible in the Pacific Northwest, such as changes in storm patterns, upwelling, flooding and erosion. Climate change also poses unknown risks. Communities in Oregon, and throughout the Pacific Northwest need to take action now to adapt to changing climate and address threats to infrastructure and natural systems. Decision makers need access to the best available scientific information about the effects of climate change in order to protect human communities, infrastructure and estuaries. Adapting to climate change will require thinking in new ways about how to manage land use, protect water quality and prepare for weather and storms. 

References

Changing Oceans, Changing World. Ocean Priorities for the Obama Administration and Congress. 2009. Joint Oceans Commissions Initiative. Washington, D.C. April 2009. 

Climate Change 2007. The International Panel on Climate Change 4th Assessment Report, Summary for Policymakers. Valencia, Spain. November 17, 2007. 

Climate Ready Communities. A Strategy for Adapting to Impacts of Climate Change on the Oregon Coast. 2009. Oregon Coastal Management Program, Department of Land Conservation and Development. Portland, Oregon. January 2009. 

Climate Ready Estuaries. 2008. Synthesis of Adaptation Options for Coastal Areas. U.S. Environmental Protection, Agency Office of Air and Radiation, Office of Water. EPA 430-F-08-024. Washington, D.C. December 2008. 

One Coast, One Future. Securing the Health of West Coast Ecosystems and Economies. Recommendations to local and state leaders from the Joint Ocean Commission Initiative. 2009. Joint Ocean Commission Initiative. Washington, D.C.