Historic Atmospheric CO2 Concentrations

Calendar Years B.P.

800100012001400160018002000

CO

2 C

once

ntra

tion

(p

.p.m

.v.)

240260280300320340360380 Siple Station (Friedli et al. 1986)

South Pole (Neftel et al. 1985)D57 (Raynaud and Barnola 1985)GISP 2 (Whalen et al. 1991)

Siple Station (Neftel et al. 1985)

o Mauna Loa Atmosphere (Keeling and Whorf 1994; CDIAC)

Reconstructed Atmospheric CO2

Calendar Years (Before 1950)0 10000 20000 30000

Atm

osph

eric

CO

2 (pp

m)

150

200

250

300

350 Taylor Dome (Indermuhle et al. 1999)Vostok (Barnola et al. 1987)Byrd Ice-core (Neftel et al.1988)

Carbon Dioxide (CO2)

Recent CO2 Changes

IPCC Reports

Carbon Dioxide

Changes in Temperature2 to 5° F by 2050

Changes in SeasonalityWarmer winters earlier springs

Water Resources

DroughtIncreasing Dry Episodes

Return of Mega-droughts

SnowpackReduced levels at low elevations

Extra-localInfluences

Dust Bowl and 50’s drought

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12

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Regional Water Influences

Lake Mead Water Level

Additional Heat-wave Days

Agriculture in Southern CaliforniaEach year, even with heat abatement efforts, extreme heat costs America’s livestock industries (dairy, beef, swine, and poultry) a collective 1.7 billion dollars. These losses come in the form of increased mortality, decreased appetite, decreased milk and egg production, and decreased reproductive fitness.

Yields of cherries, berries, table grapes, wine grapes, walnuts, and freestone peaches are projected to decline by 2050, while almond yields slightly increase during this period. Increases in average May daily low temperatures help avocado production to some degree, once this value exceeds 53.6 degrees Fahrenheit, the yields go down at a rate of about ten tons per acre for every 1.8 degree Fahrenheit increase in daily low temperature.

Warmer winterlow temps

In Citrus,lyears when the December temperature was 3.6 degrees Fahrenheit warmer than average produced crop yields that were five tons per acre larger than average.

Changes in SeasonalityWarmer winters earlier springs

Warmer Temperatures (Pathogens and Disease)

In General

Fungi that infects crop plants grow best in moderate temperatures (earlier and longer warm periods)

Wheat and Oats

Host plants may become more

susceptible to rust disease.

Forage species

become more resistant to fungi

Moisture Changes (Pathogens and Disease)

• More frequent and extreme precipitation events could result in more and longer periods with favorable pathogen environments

• Some pathogens will expand with increased moisture, whereas others will expand with reduced moisture.

• Predicted higher atmospheric water vapor concentrations with increased temperature will favor pathogen and disease development.

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Relative surface area of crops

in California for 2006

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Rising CO2 Concentrations(Pathogens and Disease)

Impacts will be on both host and pathogens.

CO2 fertilization will result in denser canopies, thus higher humidity favoring pathogens

Lower plant decomposition from higher CO2 may provide cover for overwintering, thus earlier and faster disease cycles.

Physiological changes to plant as well as pathogen

Allergies and DiseaseIncreasing pollen numbers and allergy strength

Spread of new diseases

Mosquito-Borne Rodent-Borne Water-Borne

Warmer Temperatures (Insects)

In General

Increased temperature could increase pest populations

Warmer temperatures can affect insect survival, development, geographic range, and population size

Temperatures can affect insect development directly or indirectly

The Historic Record

• Insect species diversity per area tends to decrease with higher latitude and altitude, meaning that rising temperatures could result in more insect species attacking more hosts in temperate climates

• The diversity of insect species and the intensity of their feeding have increased historically with increasing temperatures. (Bale et al. 2002)

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InsectsThose that take several years per life-cycle•These insects will tend to moderate temperature variability over the course of their life history.

Stop and go developers•Develop more rapidly during warm periods .•Increased temperatures will accelerate the development of these types of insects (more generations = more crop damage)

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InsectsMigratory Insects•Areas where they overwinter may expand with warming temperatures.

•Natural enemies and host insects may respond differently. Host insects may accelerate growth resulting in less parasitism.

•Changes in temperatures may shift gender ratios

Changes in Natural Vegetation

Pine Bark Beetles