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Climate Change and Biodiversity in King County

Climate Change and Biodiversity in King County

The effects of climate change on biodiversity are only beginning to be understood in King County, though they have already begun. Some of the impacts of climate change on biodiversity we expect include:

  • Increases in direct mortality as a result of heat stress. Like heat stress can kill people, higher air and water temperatures will kill some plants and animals. Salmon and freshwater mollusks will be most vulnerable in our aquatic systems. Many native plants that have adapted under milder conditions may not survive hot summers or freezing winters.
  • Altered growth rates and timing of life history events. Life cycles of predators may no longer match up with those of prey. If a species needs to eat but doesn't have food, the animals may die or move elsewhere. Migratory animals may arrive to find their food source is not ready to be eaten yet or already gone. If babies of a species are born at a time when their food is not yet available or it already left, they may not survive. These mismatches in timing may lead to large increases in some prey species and large decreases in other species.
  • Altered local distributions and regional range shifts. As temperatures increase, treeline at higher elevations is expected to move upslope. Therefore, alpine meadows will shrink. Species that rely on high elevations will be forced up slope until there is nowhere else to go.
  • Biological invasions. Exotic marine fishes, invasive freshwater fishes, aquatic and terrestrial plants, and more are already a problem. With earlier growing seasons and warmer temperatures, new invasions can happen. New diseases may take hold in warmer marine water and kill top predators such as the giant sunflower star. The loss of such a top predator has a domino effect that destroys entire ecosystems.
  • Food web disruptions. A breakdown of the base of the food web may occur. Microscopic animals form the base of the food chain in our region. If they die, the effects could be dramatic as the ocean food chain snaps in many places.

Conserving biodiversity in the face of a changing climate

In the face of climate change, biodiversity conservation will be of critical importance for buffering the effects of rising temperatures on regional ecosystems, damping the rates of ecological change, and reducing the potential for sudden, extreme changes in the environment. The Convention on Biological Diversity highlights the need to:

  1. identify and conserve biodiversity components that are especially sensitive to climate change,
  2. preserve intact habitats to facilitate the long-term adaptation of biodiversity,
  3. improve our understanding of the climate change/biodiversity linkages, and
  4. fully integrate biodiversity considerations into climate change mitigation and adaptation plans.

Impacts on some of our plants and animals

Some climate change impacts to the Pacific Northwest and King County include:

  • Increased average annual temperatures, increased temperatures across all seasons, significantly increased summer temperatures, and increased urban “heat island” effects, in which urban air and surface temperatures are higher than in the Rural Area due to storage of heat in pavement and buildings;
  • Sea level rise of approximately 1 foot by 2100 leading to increased coastal flooding, inundation, saltwater intrusion of coastal aquifers, nearshore habitat loss, and erosion;
  • Changes to the timing and magnitude of streamflows due to snowpack and glacier reduction, increased winter rainfall, decreased winter snowfall, and earlier spring melt;
  • Increased stress to regional water supplies due to increased frequency of drought events and increased demand;
  • Negative effects on public health including thermal stress, respiratory problems due to increased smog, and increased exposure to certain infectious diseases;
  • Increased stress to forests in the foothills, and potentially increased growth in forests at higher elevations that were snow-dominated;
  • Increased stress to plant and animal species due to vegetation changes, food web disruption, streamflow changes, and increased freshwater and marine water temperatures; and
  • Altered regional distributions of many species, including marine and freshwater phytoplankton, zooplankton, and salmonids.

Frogs and salamanders

tailed frog tadpole

Tailed-frog tadpole. Photo by J. Vanderhoof.

Amphibians are likely to be some of the most susceptible animals to climate change for several reasons:

  • They need habitat with very specific temperatures and moisture levels.
  • They are limited in their abilities to move to different locations
  • Amphibians are thin-skinned. Their thin skin makes frogs acutely sensitive to even minor changes in temperature, humidity, and air or water quality.
  • The deadly chytrid fungus thrives in warmer environments. This fungus is devastating amphibian populations.

Tailed frogs (see tadpole photo above) require cold, clean water. Read more about King County's frogs and salamanders on the Herp page.


In King County, mammals relying on higher-elevation habitats are likely to be affected by climate change. The pika is one example. Pikas are small mammals in the rabbit family that lives on rocky slopes at high elevations. They have already experienced several local extinctions over the last 50 years. Pikas can only leave their burrows to forage when temperatures are cool enough. As the climate warms, they are able to spend less time foraging and consequently are able to store less and less forage for the long winter. And in fact, some wildlife advocates have sued the Federal Government to list the Pika under the Endangered Species Act. 



White-tailed Ptarmigan. Photo by J. Vanderhoof.

Birds, more than many other animals, will be able to move as changing climate alters their habitats. They will continue to shift their ranges both poleward in latitude and upward in elevation in response to warming trends. Some birds, like the California Scrub-jay, whose range has been shifting northwards for a couple decades, will become more common. Birds like the White-tailed Ptarmigan, whose habitats are currently at 7000 ft and higher, may leave the County's alpine areas altogether. Birds like Spruce Grouse may move higher than 4000 ft elevation, which is their current lower limit.

The birds page provides a lot of additional information about birds found in King County.

Freshwater fish

As water temperatures increase,  we expect a reduction in populations of our native cold-water species. Warm-water fish species will expand their ranges. Cool/cold-water fish species will have a decrease in available habitat. Non-native fish such as smallmouth bass will compete with native salmon and trout. And warmer temperatures lead to reduced dissolved oxygen.

Salmon and trout may not have enough food if their prey are not available when the salmon need them. Some important habitats may disappear completely at critical times of the year -- some streams may dry up during the end of dry summers. And stress makes animals more susceptible to disease, predation, competition, and other physiological problems.


Some of the largest climate-driven impacts to ecological as well as agricultural and forestry systems may be mediated by changes in insect populations. Changes in timing that result from climate change could disrupt countless systems. For example, advances in flowering dates can create mismatches between pollinators and plants, between parasites and hosts, and between herbivores and their food resources. Forest pests and pathogens are already known to be expanding their ranges in response to climate change.

Marine forage fish

"Forage fish" are another example of the complex web of reactions that can ensue with a changing climate. Marine forage fish include Pacific sandlance, surf smelt, and Pacific herring. These fish are the base of the food web for many species, including salmon, marine birds, and orca whales. The fish have discreet spawning habitat requirements along the shoreline. Pacific herring need eelgrass beds. Pacific sandlance and surf smelt need upper intertidal beach areas. These habitats are located along the same shoreline where people build bulkheads. Unfortunately, bulkheads lead to the destruction of natural shoreline habitats. See the case study below for how..

Marine Shorelines, a Case Study


Forage fish and their habitat illustrate the complex web of reactions that can happen with a changing climate. Intertidal areas (areas that are under water at high tide and exposed at low tide) are heavily impacted by the bulkheads, also known as sea walls:

  • Bulkheads were historically built at or below the elevation the where forage fish spawn, so their spawning habitat was buried.
  • Bulkheads generally stop natural erosion by restricting sand and gravel from replenishing the beach and spawning habitat. Over time, the beach that remains in front of a bulkhead will disappear and cause the bulkhead to collapse
  • Bulkheads can increase the wave energy directly in front of the bulkhead. In other words, the water will crash harder into this location and wash away sand and smaller sediment. Not only does this change of substrate mean different animals would live there, but it the larger sediment is too coarse for forage fish to spawn in.
  • Bulkheads generally do not allow for organic debris (drift logs, algae) to build up on the beach. Organic debris also forms the basis for portions of the food web.
  • As sea levels rise with climate change, the amount of beach habitat will become squeezed between the higher waters and the bulkheads. This squeezing will further reduce the overall forage fish spawning habitat available.
  • This feedback cycle will further compound the negative impacts of climate change and development on forage fish.

In King County, the older developed areas are the most heavily impacted by bulkheads. These areas include Seattle and the shoreline north along the railroad corridor, which has been in place for over a hundred years. Federal Way and Vashon are currently the least impacted by bulkheads. But Alki Beach, Lincoln Park, and Golden Gardens still have sand, despite all the development and lack of bluff erosion. How is this possible? You can thank City of Seattle for trucking in sand to keep these recreational areas functioning.

Related Climate Information