The figure below provides a schematic of our research approach, along
with links to summary level information. The outermost layer is labeled
"Integrated Assessment". Integrated assessment describes our
overall research approach. Click on the heading for more information.
The middle layer is labeled "Human Dimensions". This reflects
the fact that our Human Dimensions research spans all research sectors
and climate drivers. Click on the heading for more information.
At the center of the figure is the Biophysical Climate Impacts Matrix.
The matrix contains links to summaries of our findings on the relationship
between specific "sectors" (such as forests or hydrology) and
three principal, large-scale climate patterns. Simply click on a box in
the matrix to access the summary of interest. Click on any row or column
heading for a brief explanation of the sector or climate pattern. If your
please use the text listing of matrix links at the
bottom of this page.
For a graphical summary of the impacts of climate change, follow
Research sector descriptions
The climate of the Pacific Northwest
(defined here as the states of Idaho, Oregon, and Washington; for some
purposes we also consider the adjoining areas of the Columbia River Basin)
is strongly influenced by climate events in and above the Pacific Ocean.
"Climate" is simply defined as the statistics of weather, and is often
expressed with numbers for things like long-term monthly averaged temperature
and precipitation. Important elements of any region's climate generally
change from year to year - one year may be warmer than another, or one
summer may be sunnier or cloudier than the next. The UW Climate Impacts
Group studies both past climate over periods of time from seasons to thousands
of years, and future climate over periods of time from seasons (predictions
made on the basis of the El Niño-La Niña climate cycle) to 100 years (projections
or scenarios of future climate from climate models).
Hydrology and water resources:
Water is a valuable resource in the Northwest, providing 75% of the region's
electricity and irrigating the arid lands that make up much of the region.
CIG's research on hydrology and water resources examines the effect of
regional climate fluctuations and future climate change on the amount
and timing of streamflow in PNW rivers, and the subsequent impacts on
the managed water supply and on dependent human activities, such as agriculture,
urban water supply, and the production of hydropower. Much of our research
focuses on the Columbia River basin,
one of the largest river basins in North America, which drains much of
the land area of the Pacific Northwest.
Salmon were once a staple in the diet and a centerpiece in the economies
of Native Americans and early European-American settlers in the Pacific
Northwest (PNW) and remain a cultural and ecological icon for the region.
There are seven species of salmon in the PNW: pink, sockeye, chum, chinook,
coho, steelhead, and sea-run cutthroat, with a total of 36 substantially
isolated breeding populations, or evolutionarily significant units
(ESUs). Each of these ESUs has developed a distinct migratory rhythm,
giving it a somewhat different sensitivity to climate variations at different
stages of life.
Today, wild populations of PNW salmon are at historically low numbers,
with many ESU's now listed as either Threatened
or Endangered under the Federal Endangered Species Act.
Because salmon spend part of their lives in freshwater (as juveniles
and spawning adults) and part of their lives in saltwater (for months
to years as they mature), studying their dependence on climate allows
CIG to examine both freshwater and marine ecosystems. Empirical evidence
suggests that salmon production along the entire Pacific coast is sensitive
to climate variations. [Salmon lifecycle
Evergreen coniferous forests cover much of the landscape in the Pacific
Northwest and provide fish and wildlife habitat, as well as a broad array
of goods and services for human society. Climate can affect forest establishment,
growth and persistence both directly and indirectly (Figure WEBFforestimpacts).
Climate variations affect forests directly by limiting or allowing various
physiological processes (e.g., photosynthesis, seedling establishment).
Climate variations profoundly influence forest conditions indirectly through
changes in the frequency or character of disturbances, such as wildfire,
insect outbreaks, and windthrow. Through both types of mechanisms, climate
variability and future climate change can influence forest ecosystem structure,
function, and composition.
The Pacific Northwest has three distinct "coasts" (Figure 8Fcoastmap):
the Pacific Ocean coast; the shores of the estuaries fronting the Pacific
Ocean; and the shores of the inland marine waters of Washington's Puget
Sound and the Strait of Juan de Fuca. In our assessment of the consequences
of climate variability and climate change in the coastal zone, we have
focused primarily on the physical landscape, but have also addressed biological
and ecological consequences, in preparation for future phases of the project.
Climate related hazards affecting the physical landscape of the coastal
zone include erosion, bluff landsliding, flooding, and inundation.
Climate Driver Descriptions
ENSO (El Niño/Southern Oscillation):
The El Niņo/Southern Oscillation (ENSO) is the planet's dominant mode
of climate variability on the seasonal to interannual time scale. El Niņo
(sometimes called the warm phase of ENSO) refers to a suite of anomalous
climate conditions in the tropical Pacific characterized by unusually
warm sea surface temperatures and weak trade winds. La Niņa (the cool
phase of ENSO) refers to the climate state characterized by anomalously
cool sea surface temperatures and stronger than average trade winds. ENSO
events have pronounced global climatic consequences, affecting the Pacific
Northwest on interannual timescales. Monthly values for a common ENSO
index (the Niño3.4 index) are shown in Figure
PDO (Pacific Decadal Oscillation):
The Pacific Decadal Oscillation (PDO) has been described as a long-lived
ENSO-like pattern of Pacific climate variability. As is the case for El
Niņo and La Niņa, extremes in the PDO pattern are marked by widespread
climatic variations in the Pacific Basin and North America. Two main characteristics
distinguish the PDO from ENSO. First, typical PDO "events" have persisted
much longer (20-30 years) than ENSO events (1-2 years). Second, the climatic
fingerprints of the PDO are most visible in the region of the North Pacific
and North America, with secondary climatic influences in the tropics,
whereas the fingerprints of ENSO are most visible in the tropics.
Several independent studies find evidence for two full PDO cycles in
the past century: cool PDO regimes lasted from 1890 to 1924 and again
from 1947 to 1976, while warm PDO regimes spanned 1925 to 1946 and from
1977 through at least the mid-1990s (Minobe 1997; Mantua et al. 1997).
Recent evidence suggests that the PDO may have switched to a cool phase
before 1997 (Hamlet and Lettenmaier 1999a). Causes for the PDO are unknown
(National Research Council 1998). Monthly values for a common PDO index
are shown in Figure 3.
Here we use the term "climate change" to refer to future changes in climate
resulting from human activities (primarily the burning of fossil fuels).
An extensive international research effort has been underway for many
years to simulate the future climate changes that may occur as a result
of human activities. This effort has concluded that humans are influencing
climate already and that the climate will change considerably over the
next century and beyond. [For more information on this statement,
see our Climate Dynamics page]. A variety of
global climate models have been examined for the changes in climate that
the PNW can expect for the decades of the 2020s, the 2040s, and the 2090s.
The models generally agree that the PNW can expect warmer, wetter winters
and warmer summers, with 1-3 degrees (F) warming by the 2020s. Global
sea level rise, projected to be between 6" and 37" with a best guess of
19", will also affect our coasts.
Link to Climate Change Impacts summary figure.
Text listing of the Matrix
ENSO x PNW Climate
ENSO x Hydrology and Water Resources
ENSO x Salmon
ENSO x Forests: no data
ENSO x Coasts
PDO x PNW Climate
PDO x Hydrology and Water Resources
PDO x Salmon
PDO x Forests
PDO x Coasts: no data
Climate Change x PNW Climate
Climate Change x Hydrology and Water Resources
Climate Change x Salmon
Climate Change x Forests
Climate Change x Coasts