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Climate Change Advanced

Climate Change in the Pacific Northwest

According to the latest (2007) climate change assessment from the Intergovernmental Panel on Climate Change (IPCC), climate change is occurring. The atmospheric concentrations of leading greenhouse gases are increasing, ocean and air temperatures are rising, permafrost is melting, and global average sea level is increasing. Furthermore, the IPCC has shown that even with significant near-term decreases in greenhouse gas emissions, the current concentration of greenhouse gases in the atmosphere has effectively committed Earth’s natural and human systems to continued warming through the end of the 21 st century. This means that both mitigation (i.e., reducing greenhouse gas emissions) and adaptation (i.e., preparing the for the impacts of climate change) will be essential to minimizing the impacts of climate change.

- You might want to add in graph of atmospheric concentrations of CO2. (Found on IPCC’s webpage or CIG’s climate change page: http://cses.washington.edu/cig/pnwc/cc.shtml)

Climate change will have many impacts on the Pacific Northwest’s human and natural systems. Much of what we know about projected climate change in the Pacific Northwest comes from the University of Washington’s Climate Impacts Group (CIG).

Observed Climate Change in Pacific Northwest

The climate of the PNW has changed during the past 100 years. Observed 20th century changes include:

  1. Temperature has increased. Average annual temperature increased 1.5°F (0.7-0.8°C) in the PNW between 1920 and 2003. Although the warmest year was 1934, the warmest decade was the 1990s. (Mote 2003)
  2. Trends in winter season and daily minimum temperatures have been largest. Temperature trends from 1916-2003 were largest from January-March. Minimum daily temperature rose faster than maximum daily temperature through the mid-20th century. In the second half of the 20th century, minimum and maximum temperature rose at about the same rate. (Mote 2003, Hamlet and Lettenmaier 2007).
  3. Range of precipitation during the cool season has increased and is more variable from year to year. (Hamlet and Lettenmaier 2007).
  4. April 1 snow water equivalent (SWE) declined at nearly all sites in the PNW between 1950 and 2000. The declines are strongest at low and middle elevations, and can be explained by observed increases in temperature and declines in precipitation over the same period of record (Mote et al. 2003, Hamlet et al. 2005, Mote 2006).
  5. Timing of peak runoff has shifted. Timing of the center of mass in annual river runoff in snowmelt basins shifted 0-20 days earlier in much of the PNW between 1948 and 2002 (Stewart et al. 2005).
  6. Sentence about lack of significance in precipitation change?

 

While it is premature to assume that anthropogenic (i.e., human caused) climate change is exclusively driving these trends, these trends cannot be fully explained by climate variability alone. Additionally, the trends are consistent with observed global changes and projected global and regional climate change impacts.

 

Pacific Northwest Projected Climate Impacts

The Climate Impacts Group projects the following changes to the Puget Sound Region from climate change:

Projected Changes in Temperature and Precipitation


Year

Temperature Change (degrees F)

Precipitation Change

2020s

+2.2

( +1.1 to +3.3)

+1

(-9 to +12)

2040s

+3.5

(+1.5 to +5.2)

+2

(-11 to +12)

2080s

+5.9

(+2.8 to +9.7)

+4

(-10 to +20)

Impacts to Seattle from Changes in Precipitation and Temperature


Temperature

Precipitation

Energy: Increased building energy demands, mostly for cooling, as summer temperatures increase.

Heat waves: Intense heat waves to adversely affect human health.

Threats to trees and other plants: Some tree and other plant species may no longer survive in Seattle. Urban trees will become more susceptible to insects.

Decrease in snowpack: More precipitation to fall as rain rather than snow, with a statewide reduction in snow pack of 28-29% by the 2020s, 38-46% by the 2040s, and by 56-76% by the 2080s.

Change in timing of precipitation: Total precipitation to remain roughly the same as in 20th century, but timing of that precipitation will change, potentially including increased winter storm events and less precipitation in summer.

Increase in flooding: Increased flooding, leading to property damage, roadway damage, beach erosion, and bluff landslides.

Increased stress on stormwater infrastructure: Increased storm events will likely stress drainage and storm water infrastructure (in particular, combined sewer overflows).
Increase threats to fish populations: Reduced summer and fall stream flow will stress fish life cycles, making salmon recovery in Seattle streams more difficult.

 

Projected Sea Level Rise for Seattle 


Near-Term Changes (Through 2050)

Long-term Changes (Through 2100)

Impacts to Seattle

Low: 3”

Low: 6”

 Approx. 700-1,000 acres of dry land at risk of being inundated by water.

Significant loss of estuarine beach in Seattle by 2100.

Downtown waterfront likely to be impacted by episodic flooding.

Pollution from flooding of lowland industrial areas.

Coastal beaches may shift inland.

Likely decrease in shellfish populations from increased acidity, disease, and increased harmful algal blooms.

Medium: 6”

Medium: 13”

 

High: 22”

High: 50”

 

 

 

 

Additional Projected Impacts to Washington State:

Decline in snow pack: decrease in snowpack by 38-46% by the 2040s (Elsner et al. 2009).  A 13- 16% decrease in summer hydropower by the 2040s. Hydropower accounts for about 70% of electrical energy production in Pacific Northwest and is affected by changes in streamflow (Hamlet et al 2009).

Water supply

  1. Puget Sound: Puget Sound water supplies will see a shift in the timing of peak river flow from late spring (driven by snowmelt) to winter (driven by precipitation) and reduced levels of summer and fall storage. However, Puget Sound water supply systems will generally be able to accommodate changes through the 2050s in the absence of any significant demand increases. For more details, see Vano et al. 2009(a).
  1. Yakima: The Yakima basin reservoir system will likely be less able (compared to 1970-2005) to supply water to all users, especially those with junior water rights. Without adaptation, shortages would likely occur 32% of years in the 2020s, 36% of years in the 2040s, and 77% of years in the 2080s (compared to 14% of years for the period 1916-2006). Due to lack of irrigation water and more frequent and severe prorating, average production of apples and cherries would likely decline by approximately $23 million (about 5%) in the 2020s and $70 million (about 16%) in the 2080s. For more details, see Vano et al. 2009(b). 

 

Productivity of farms, forests, & fisheries

  1. Yields for dryland winter wheat are expected to increase by 13- 24%, irrigated apples are expected to increase by 9% and irrigated potatoes are expected to decrease by -2 to +3% (Stöckle et al. 2009), assuming continued availability of water and benefits from CO2 levels.
  2. Junior water right holders in the Yakima Basin are expected to have a 40-50% decrease in cherry and apply yields, despite benefits from the CO2 fertilization effect (Vano et al. 2009b).
  3. Increase in aggressive insects and invasive weeds, resulting in need for more effective environmentally friendly approaches to pest control.

Prevalence of oppressive heat & humidity

  1. Heating energy demand (top) and cooling energy demand (bottom) for projected population growth and regional warming averaged over Washington. Units: million person-heating degree days (HDD) or million person-cooling degree days (CDD).(1) For a larger version of the graph, click here
  2. Increase in cooling demand by 400%, which will increase electricity demand and peak electrical power loads in the summer.
  3. Increase of 156 heat-related deaths of people over age 45 from heat events in the Greater Seattle area by 2045 (Jackson 2009).
  4. Building energy demand is expected to increase with warming and population growth. The following chart shows the projected energy demand changes with warming and population growth by heating and cooling degree days (number of degrees cooler or warmer than a base temperature of 65° F)

Formation & dispersion of air pollutants

  1. Increase of 132 deaths from poor air quality between May and September (Jackson 2009).
  2. Increase in negative health impacts from poor air quality, especially to elderly, very young, economically disadvantaged, those who work outside, and those who have ill health (Whitley-Binder 2009).

Damages from storms, floods, droughts, wildfires

  1. Increase in wildfire in the Columbia Basin by threefold by 2040s (Littell et al. 2009).
  2. Increase in damage from flooding, stormwater overflow, and high winds.
  3. Increase in insurance costs.

Property losses and damages from sea-level rise

  1. Options for mitigating impacts of sea level rise on Seattle’s shoreline are costly and include raising the height of piers and buildings, building dikes and seawalls, or abandoning coastal sites.
  2. Inundation of coastal industrial areas, including the Seattle and Tacoma Ports, will have negative impacts on water quality, transportation networks, and economic activity.

Expenditures on engineered environments

  1. Increase in heating and cooling demand by 30% by 2040s, despite reduction in heating degree days, or days when the temperature falls below 65?F (Hamlet et. al 2009).

Forests

  1. Warmer temperatures and declining snowpack are projected to increase water stress on forests, increase forest fire risk, and increase the number of mountain pine beetle outbreaks (Littell et al. 2009).
  2. Pine beetle may reduce the productivity of Douglas-fir, an important commercial species for the Washington economy.

Distribution & abundance of species, including salmon

  1. The amount of time that stream temperatures exceed 70°F, causing migration barriers and thermal stress for salmon in the interior Columbia Basin will quadruple by the 2080s (Mantua et al. 2009).
  2. Winter flood events may reduce reproductive capacity for salmon by destroying nests and damaging eggs.