Ecological effects of global climate change

I.  The problem:  rising CO2 and climate change

A.  Review of historical trends in CO2 and climate

1.  Atmospheric increases in CO2 and the carbon cycle



B.  Physical effects of climate change



1.  Sea level rise


2.  Hurricane intensity


II.  Ecological consequences of increased CO2

A.  Higher CO2 levels can increase plant productivity
B.  Increased CO2 may benefit plant growth, but have negative effects on consumers

III.  Ecological consequences of increased temperature

A.  Changes in life cycle timing

1.  Crick, et al (1997, 1999)
•    65 British bird species studied from 1971-1995,
•    31% exhibited a significant trend towards earlier egg laying (shift averaged 8.8 days)
•    Only 1 species layed eggs significantly later

2.  Bradley, et al 1999
•    Study of springtime events over a 61 year period
•    ‘Phenophases’ include phenological events like first bloom, first arrival, etc.
•    Approximately 1/3 showed significant, earlier arrival, 1/3 showed no response, and 1/3 were borderline
•    Events that tend to occur earlier in the year showed a stronger response over time

3.  Fitter and Fitter (2002)
•    Studied 385 plant species in Great Britain
•    Found significant decrease in time of first flowering in 16% of species (by ave = 15 days)
•    Species most affected were early-blooming, woody, and insect pollinated


4.  Root et al, responses found across many species



B.  Changes in species distributions and abundances

1.  Parmesan 1996
•    Censused Checkerspot Butterflies in 115 sites throughout its range from Mexico to Canada
•    Documented persistence and extinction in 151 previously recorded populations
•    Excluded sites where habitat was degraded
•    Extinctions were more likely in southern latitudes than in northern latitudes (shift 92 km northward)
•    Extinctions were more likely at low elevations than at high elevations (shift 124 m upward)


2.  Perry, et al (2005)
•    Increased ocean temperatures shifted ranges of fish northward


3.  Parmesan and Yohe (2003)
Survey of 1200 plant and animal species

On average organisms shift  5km/decade poleward  //  5m/decade up in elevation

3.  Conservation priorities must shift to account for changing distributions under a scenario of changing climates



4.  Changing distributions have caused are projected to cause extinction

Golden Toad and Monteverde Harlequin frog, along with over 50 other tropical amphibians, already driven extinct



C.  Changes in Species Interactions and Communities

1.  Visser et al (1998)
•    Climate change may have different effects on phenologies of interacting species
•    Date of egg laying in Great Tits has not changed in 23 years, while the climate has warmed
•    Peak caterpillar biomass is now nine days earlier
•    The main selection pressure on laying date is synchrony with caterpillar availability
•    Birds are phenotypically plastic but:
        – may not acquire resources for egg production earlier in the season
        – may lay eggs at similar times relative to initial caterpillar development, but higher temperatures after egg laying may lead to faster caterpillar growth

2.  Holbrook et al (1997)
•    The ocean temperature off CA increased very suddenly by about a degree in the mid-70s
•    Northern species dominated the reef fish community
•    Over the last 25 yr, Southern species have taken their place
•    There has been a decrease in total species richness
•    Abundance of Northern fishes and local fishes has declined
•    Abundances of Southern fishes increased, then decreased
•    Juvenile recruitment of all species is strongly correlated with zooplankton biomass
•    Warming of the ocean off CA has reduced upwelling of nutrients to the photic zone, and thus reduced productivity of algae and zooplankton



D.  Biodiversity Conservation for a changing climate

1.  Bioclimatic modeling


2.  Biophysical and demographic modeling


3.  Additional details
        Dispersal,         Increases diversity loss by ~8%

        Local adaptation

        Species interactions


4.  Conservation measures

       -  Increasing connectivity
       -  Assisted migration

IV.  Carbon stabilization
1.  Carbon emissions are projected to increase
2.  What technologies exist now to reduce project increases?
3.  Could we select some set that would stabilize total emissions?
4.  Pacala and Socolow have proposed 15 "wedges" that each reduce 1/7 of projected increases in carbon emissions