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Atmosphere, Climate, Oceans, Weather



California Climate: Pacific Ocean Connection
Topic(s): Atmosphere, Climate, Oceans, Weather

Scenario: The 1999-2009 period has been remarkably dry in California and the Southwest with these regions subjected to one of the worst droughts in an approximately 500-year record. Historic low water levels in several Colorado River reservoirs mark this period. These low levels are of concern as these reservoirs remain a major source of water for California and other western states. Another major source of California water is the Sierra Nevada snowpack. Warming has led to earlier snowmelt and water runoff in these mountains, which means less water remains to meet the Golden State's needs for the dry summer season. California imposed water rationing in summer of 2009. In Los Angeles County, residents could only use lawn sprinklers on Mondays and Thursdays, after 8 at night and water fees increased in many areas of the county. But its not just getting drier in California, it's also getting hotter.

As California temperatures climb, heat waves have become more frequent. In 2006, over 160 Californians died in a brutal July heat wave. In metropolitan Los Angeles, the frequency and duration of heat spells over the last 100 years have increased dramatically. Overall, most California urban areas show much faster warming than the state itself due to a phenomenon called the urban heat island. The urban heat island (UHI) results from the urban core of cities being warmer than their surrounding rural areas because of the changes in surface properties such as more heat absorbing materials like asphalt, concrete and glass.

Increased temperatures may also be responsible in part for an increased frequency of wildfires. Major wildfires have blackened large areas of California in recent years. The August 2009 Station fire occurring in the mountains just north of Los Angeles was the largest wildfire in the county's history. The constant smoke and falling ash made breathing difficult and not unsurprisingly the air quality over large portions of the Los Angeles area was very unhealthy. The 2003 Cedar fire near San Diego, California burned nearly 144,000 acres, the largest blaze in the state's history. In 2007 the state totaled the most acres burned with over 440,000. Research shows wildfire damage continues to increase in the western U.S.

Many people tend to attribute increased temperatures and fires, and a more persistent drought in California to global warming. However, global warming may not be the only cause for these events. Strong evidence exists suggesting that natural changes in the Pacific Ocean may have an even greater influence on state temperatures and precipitation. One such large-scale natural oceanic feature impacting California climate is the Pacific Decadal Oscillation (PDO). The PDO is characterized by cool or warm phase shifts in North Pacific sea surface temperatures which commonly persist for 20-30 years. In the cool or negative phase, east Pacific sea surface temperatures (SSTs) are below normal. For the positive or warm phase, east Pacific SSTs are above normal. Cool or negative PDO phases occurred from 1890-1924 and from 1947-1976. Warm or positive phases typified the periods from 1925-1946 and from 1977 through the mid-1990's. Climate records in California show similar shifts in temperature and precipitation as the PDO changes phases. Generally, warm PDO years correspond to warmer California temperatures and above normal southern California rainfall. The opposite generally occurs with the cool PDO years. Other natural events also influence California climate.

Superimposed on the PDO cycles are smaller-scaled El Nino/La Nina events persisting for approximately a year. These events are typically defined as significantly warmer or cooler than normal sea surface temperatures in the central and eastern equatorial Pacific. Climatic impacts associated with La Nina events are similar to those tied to the cool PDO phases. Conversely, climatic conditions related to El Nino episodes parallel those of warm PDO phases. At the same time, the oceanic changes producing El Nino/La Nina events are interrelated with Pacific atmospheric changes termed the Southern Oscillation (SO). The SO is a phenomenon where surface air pressure in the western and eastern tropical Pacific oscillates in opposite directions, i.e., as one increases the other decreases, and visa versa.

Climatic impacts associated with cool PDO phases are similar to La Nina events and those associated with warm PDO phases parallel El Nino episodes. Southern California climate is significantly modified by these interannual and interdecadal climate shifts. In general, warm PDO years corresponds to warmer California temperatures and above normal southern California rainfall. The opposite generally occurs with the cool PDO years.

Your group comprises Arnold Schwarzenegger's Climate Action Team (CAT), which consists of consultants from various state departments. CAT is charged with evaluating the impacts that climate change is having on the state (i.e., economy, resources, human health) now as well as in the near future. Your task is to help present a concise report about how the state's climate is changing and what effects these changes may have on the state's resources (water, energy, forests and agriculture). Your report is crucial to informing state managers and policy makers, including the Governator.


Date: 8/26/2009

Scenario Images:

California Temperature Trends 1950-2000
California is warming, but the rates of warming (degrees F per decade) vary by region, with the more urban (shown as grey areas) southern regions warming the fastest and rural regions the slowest. Large urban centers like Los Angeles have shown the greatest increases in temperatures. Source: LaDochy et al, 2007 .
Enlarge image by clicking here.

Los Angeles Annual Temperatures, 1887-2008
Although the urban heat island effect is evident with over 5 F warming, the PDO signal can be seen when smoothing the data (see blue line). Individual El Nino years show up as peaks, while La Nina years are often dips in the record.
To see figure enlarged click here.

Southern California precipitation 1895 to 2008
Annual water years (July 1-June 30) rainfall in coastal southern California does not show any marked change over the last 100+ years. However, strong El Nino years show up as peaks, while La Nina years are generally dips. The smoothed running mean shows the PDO influence with lower rainfall during cool phases and higher rainfall during warm phases.

Droughts in California
This 1976 photo shows cracking, dry lakebed near Folsom, CA. With water demands growing along with population, droughts pose the greatest threat to the state's water resources. Source:

Wildfires in southern California 2003
Satellite image of October 27, 2003 southern California wildfires. Dry weather and strong Santa Ana winds contributed to massive damage.

PDO phases
Typical wintertime Sea Surface Temperature (colors), Sea Level Pressure (contours) and surface windstress (arrows) anomaly patterns during warm (on the left) and cool phases (on the right) of PDO.
See enlarged image .
Source for image:

PDO Time Series 1900-2009
20th century PDO "events" persisted for 20-to-30 years, while typical ENSO events persisted for 6 to 18 months. The "cool" PDO regimes (in blue) prevailed from 1890-1924 and again from 1947-1976, while "warm" PDO regimes (in red) dominated from 1925-1946 and from 1977 through the mid-1990's.
See enlarged image .

The 1997-98 El Nino was the strongest of the century, with dramatic climatic impacts around the world. The red and bright white areas over the eastern equitorial Pacific indicate the immense area of unusually warm water.

Following the largest El Nino of the century was a very strong La Nina event in late 1998 and early 1999. Climatic conditions nearly reversed from the previous year.

SOI TimeSeries
The Southern Oscillation Index measures the magnitude of the surface air pressure difference between the tropical western and eastern Pacific. When the SOI is negative, conditions favor the development of El Ninos, while positive SOI values favor La Nina events.



California Climate Change and Energy (Cycle A)
This website contains several educational resources, including lesson plans, videos, newspaper and journal articles, interactive educational games for reducing energy consumption, conference proceedings and links to other California resources on climate change and global warming.


Climate Change and California Water Resources (Cycle A)
This government document illustrates how climate change is impacting the state's water resources and how the state can plan to protect its resources. Connections to agriculture, energy, fires, natural ecology and health are discussed.


Climate change in California: Assessing the Risks (Cycle A)
Climate study on how global warming will impact the various sectors of California (water, energy, agriculture, wildfires, health, forestry).


El Nino and La Nina and California Rainfall (Cycle A)
This study shows the basic relationships between the El Nino/La Nina events and California rainfall. Regional differences are also shown.


Natural climate variability: PDO and ENSO (Cycle A)
NASA webpage provides basic information on natural climate phenomena such as the Pacific Decadal Oscillation and El Nino-Southern Oscillation and how they affect global weather and climate events.


Warmer, drier weather may lead to more California wildfires (Cycle A)
Recent studies have linked recent warmer temperatures and drier conditions in the western U.S. to increasing wildfires.


California Climate Tracker (Cycle B)
The California Climate Tracker is an interactive tool to plot and retrieve climatic data for state climatic stations, regions, the entire state. By choosing the location and data (temperatures, precipitation) the student can plot the trend of temperatures (max, min, mean)or precipitation (annual, seasonal, water year, anomaly)for the years of record, 1895 to present.


Climate change impacts on human health (Cycle B)
Recent warming has led to increases in heat waves. Extreme temperatures, especially in cities, can lead to stress on human health. The July 2006 heat wave was responsible for over 160 deaths in California.


Climate variability-viewing climate change over different timescales (Cycle B)
This NOAA resource introduces the concept of timescales in describing climate change using a timescale slider to view climate events over increasingly longer time periods. There are many links to paleoclimate resources,data, lesson plans and a tutorial.


Global Temperature Trend Mapper (Cycle B)
Climate analysis tool allows students to investigate temperature anomalies or temperature trends on a global scale for different time periods using NASA GISS analyzed data.


JPL Climate Time Machine (Cycle B)
By clicking on the "Climate Time Machine" link, students can use the time slider to view changes in sea ice, sea level, CO2 levels and global air temperatures over several decades. How do these changes support the concept global warming is taking place?


Southern California Heat Waves are Becoming More Frequent and Lasting Longer (Cycle B)
Temperature data from the last 100 years shows that urban southern California heat waves have increased both in frequency and duration.


Climate change and California vineyards (Cycle C)
The recent warming trend in northern California has led to greater quantity and better quality of California wines.


Climate Literacy: Essential Principles of Climate Science (Cycle C)
Downloadable brochure describes 7 main concepts that scientists consider most important in understanding climate science. Each concept has several supporting informative discussions.


Effects of climate change today (Cycle C)
Website describes various types of evidence of climate change taking place today in the atmosphere, hydrosphere, biosphere and lithosphere.


Eyes on the Earth (Cycle C)
This new visualization website provides students with opportunity to access real-time satellite data and information about data collecting satellites. The link also allows students to interactively play games using satellite data, such as finding world cities with the largest CO2 emissions.


Global warming solutions Act, Assembly Bill AB-32 (Cycle C)
California was the first state to enact a plan to combat global warming by reducing greenhouse gases.


Sample Investigations:


Climate change and the California coastal ocean (Cycle A)
This COSEE-West workshop includes audio, videos, animations, lesson plans, curricula and teacher's guides showing the relationships between the Pacific and California climate change.
Difficulty: intermediate


Feeling the Heat: Urban Heat Island Lesson (Cycle B)
This "Window on the Universe" classroom activity lets students learn about the urban heat island effect by investigating which areas of their schoolyard have higher temperatures. Then they analyze data about how the number of heat waves in an urban area (LA) has increased over time with population.
Difficulty: intermediate


Ocean currents, sea surface temperatures and climate change (Cycle B)
This lesson plan allows students to discover the link between ocean temperatures and currents and global and regional weather and climate. This link can help explain recent climate change.
Difficulty: advanced


The return of El Nino (Cycle B)
This climate education newsletter includes activities, lessons, resources on how Pacific changes, like El Nino and PDO, influence climates.
Difficulty: intermediate


The Great Climate Change Debate: Natural or Human? (Cycle C)
This is one of several lesson plans created by the Keystone Center on climate change topics. This lesson lets students learn about the issues concerning climate change in a debate style activity. Links to resources, other related activities are found here for Grades 9-12.
Difficulty: intermediate




  • Science
    National Science Education Standards - Science Content Standards The science content standards outline what students should know, understand, and be able to do in the natural sciences over the course of K-12 education.
      The understandings and abilities associated with the following concepts and processes need to be developed throughout a student's educational experiences:
      • Evidence, models, and explanation
      • Constancy, change, and measurement
      • Science as Inquiry (Std A)
        • Abilities necessary to do scientific inquiry
        • Understanding about scientific inquiry
      • Physical Science (Std B)
        • Structure and properties of matter
        • Motions and forces
        • Interactions of energy and matter
      • Earth and Space Science (Std D)
        • Energy in the earth system
        • Geochemical cycles
      • Science and Technology (Std E)
        • Abilities of technological design
        • Understanding about science and technology
      • Science in Personal and Social Perspectives (Std F)
        • Personal health
        • Population growth
        • Natural and human-induced hazards
        • Science and technology in local, national, and global challenges
  • Geography
    Geography for Life: National Geography Standards, 1994
      Geography studies the relationships between people, places, and environments by mapping information about them into a spatial context. The geographically informed person knows and understands:
      • How to use maps and other geographic representations, tools and technologies to acquire, process, and report information from a spatial perspective
      Physical processes shape Earth’s surface and interact with plant and animal life to create, sustain, and modify ecosystems. The geographically informed person knows and understands:
      • The physical processes that shape the patterns of Earth’s surface
      The physical environment is modified by human activities, largely as a consequence of the ways in which human societies value and use Earth’s natural resources, and human activities are also influenced by Earth’s physical features and processes. The geographically informed person knows and understands:
      • How human actions modify the physical environment
      • How physical systems affect human systems
      Knowledge of geography enables people to develop an understanding of the relationships between people, places, and environments over time — that is, of Earth as it was, is, and might be. The geographically informed person knows and understands:
      • How to apply geography to interpret the present and plan for the future
  • Technology
    The International Society for Technology Education From and
      • Students demonstrate a sound understanding of the nature and operation of technology systems.
      • Students are proficient in the use of technology.
      • Students understand the ethical, cultural, and societal issues related to technology.
      • Students use technology tools to enhance learning, increase productivity, and promote creativity.
      • Students use productivity tools to collaborate in constructing technology-enhanced models, prepare publications, and produce other creative works.
      • Students use telecommunications to collaborate, publish, and interact with peers, experts, and other audiences.
      • Students use technology to locate, evaluate, and collect information from a variety of sources.
      • Students use technology tools to process data and report results.
      • Students evaluate and select new information resources and technological innovations based on the appropriateness for specific tasks.
      • Students use technology resources for solving problems and making informed decisions.
      • Students employ technology in the development of strategies for solving problems in the real world.
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