reminder by wanghonghx

VIEWS: 59 PAGES: 33

									   Climate change conference – reminder
       Anyone?

   Your exam                                        Where we stand
       The good
       The not-so-good

   Your paper (Prospectus due Friday November 19)
       Your large question
       Your sub-questions

   The Readings?
       Reader?
       Website?
       Other?

   CC and Gender?




    1                                                7/1/2011
Biological Dimension of Climatic-Change
Fingerprint
       What is a fingerprint
           Fingerprints are changes that show a certain pattern that is
            unique to a specific climate-change driver.
           [see online info from Pew Center on Global Climate Change]

           Question:
               Are there any general effects of current warming across natural
                systems?
               Is it possible to discern a global-warming fingerprint?




    2                                                            7/1/2011
IPCC and Degrees of Confidence
Quantitative Scale:

        95% or greater   Very High Confidence

        67-95%           High Confidence

        33-67%           Medium Confidence

        5 – 33%          Low Confidence

        Less than 5%     Very Low Confidence

 3                                          7/1/2011
IPCC and Degrees of Confidence
Qualitative Scale:

     Well Established – Lots of evidence; high consensus
     Established but Incomplete – high consensus on
          limited information
     Competing Explanations – Lots of evidence; alternative
     explanations
     Speculative – Little evidence and many plausible
          explanations



 4                                           7/1/2011
The IPCC Dynamic
“We have very high confidence that X might happen!”

“We have medium to low confidence that X will happen!”

Converged to the notion that the statements should speak
 to the “will” alternative for a baseline.




 5                                        7/1/2011
Observed Changes in Physical and Ecological Systems
(from IPCC 2001)




        hydrology /   sea ice   animals   plants   study covers      study based on
    6   glaciers                                                     remote sensing
                                                    large area7/1/2011
  Key Conclusions from IPCC
 Recent Regional Climate Changes, particularly Temperature Increases, have
            Already Affected Many Physical and Biological Systems
                                                (high confidence, or >67% sure)

Biotic change: 44 regional studies, 400 plants and animals, 20 to 50 years
Physical change: 16 regional studies, 100 processes, 20-150 yrs
         non-polar glacier retreat
         reduction in Arctic sea ice extent and thickness in summer
         earlier plant flowering and longer growing season in Europe
         poleward and upward (elevation) migration of plants, insects and animals
         earlier bird arrival and egg laying
         increased incidence of coral bleaching
         increased economic losses due to extreme weather events




 7                                                                               7/1/2011
                             Figure 19-8-1: Summary of Lines of Evidence

                                                                                                Risks of large scale
                          Very low                                             Higher           discontinuities


                          Positive or Negative Monetary;
       Observations




                          Most People Adversely Affected
                                                              Net Negative in All Metrics       Aggregate impacts


                          Negative for some                             Negative for Distribution
                          regions                                       most regions of impacts

                                                                                     Risk of extreme
                          Increase                                    Large increase weather events


                                                                                                Risks to unique &
                          Risks to Some                               Risks to Many
                                                                                                threatened systems
-0.7                  0            1             2            3            4                5

       Past                                          Future
                          Increase in Global Mean Temperature after 1990 (°C)
   8                                                                                  7/1/2011
Parmeson and Yohe (2003)
   Combined biological and economic approaches to examine natural systems
   Assessed data-sets and individuals cases available in scientific literature
    using three variables
       Proportion of observations matching climate-change predictions
       Numbers of competing explanations for these observations
       Confidence of relating each observation to climate change
   To overcome any literature bias (negative bias), used only multi-species
    studies that reported neutral and negative climate correlations as well as
    positive ones
   Focus on: phenological effects (season changes on lives of plants and
    animals)




    9                                                            7/1/2011
Has the climate change of this past 100
years had any effects?
         IPCC - “recent regional climate changes, particularly
     temperature increases, have already affected many
     physical and biological systems.”




    10                                          7/1/2011
results
    For range boundaries of 99 species of northern-
     hemisphere temperature bird, butterfly and alpine herb at
     the end of the 20th century  moved on average 6.1 km
     north or same number of meters upwards per decade
    Total of 172 species of herb, butterfly, shrub, tree and
     amphibian – earlier spring timing of 2.3 days per decade
    ~ 87% of the species that showed any change – showed a
     change expected with climatic warming




    11                                         7/1/2011
Edith’s Checkerspot (Euphydryas editha)




      12                                  7/1/2011
Diagnostic Biological Fingerprint



    Temporal
       - Advancement of timing or northward expansion in warm
         decades (1930s/40s & 1980s/'90s)
       - Delay of timing or southward contraction in cool decades
        (1950s/'60s)
    Spatial
     Different behaviors at extremes of range boundary during particular climate phase,
        e.g. expansion at northern range boundary simultaneous with contraction at
             southern range boundary during warming period
    Community
     Abundance changes have gone in opposite directions for cold-adapted vs. warm-
     adapted species.
        e.g. lowland birds increasing and montane birds decreasing at
             mid-elevation site.


13                                                                  7/1/2011
Conclusions

    Parmeson and Yohe:
        high to very high confidence that regional climate changes
         (resulting from global warming) have had impacts on wild
         species
        Observed changes are typically small in magnitude, but are
         likely to be an important factor in long-term persistence of
         species and stability of ecosystems




14                                                    7/1/2011
Phenology
    Phenology: the study of a plant or animal’s progression
     through its life cycle in relation to the seasons
    Another main indicator of climatic fingerprint
    In Britain, for example, flowering and leafing occur 6 to 8
     days earlier for every degree C rise in temperature
    Species react differently: oak (Quercus) responds twice as
     fast as ash (Fraxinus) to an increase in temperature
    European and North American phenological sets: changes
     (probably) associated with CC, esp with regards to earlier
     spring phenology
    Note: a number of the major climate-related oscillations
     have a phenological effect

    15                                          7/1/2011
Important to know the particular species’
requirements
    Migratory black-tailed godwit
        Shore bird
        Winters between Britain and Iberia
        Breeding in summer in Iceland
        Breeding pairs – high partner fidelity
        Male and females winter in different locations – but arrive in Iceland
         typically within 3 days of each other
        ?: how this degree of synchrony is maintained when the
         environmental conditions at the different sexes’ wintering sites are
         dissimilar?
    Pied flycatcher
        Migration is timed to availability of food for its nestlings
        However – in parts of the Netherlands the caterpillars is now at its
         food peak early in the season. There – the flycatcher population is in
         decline
        Will it be able to adapt in time?

    16                                                      7/1/2011
        Biological communities and species shift
   Some species do not migrate – but will shift their geographical position or
    range in response to CC
   Climate is but one factor of many that determine a species’ spatial distribution
    – species rarely move uniformly with each other in response to climate change
   Plus
   Different species migrate at different rates
   Thus: takes time for ecological communities to stabilize after a period of CC
   Species at the leading edge of shifts/migrations tend to migrate faster than
    those already established
   Changes are asymmetrical: species invading faster from lower elevations or
    latitudes than resident species receding upslope or poleward
       Result: increase in species richness of communities at leading edge of migration
       Transitory biodiversity
       Plus: many of today’s systems are either managed or bound by land managed by
        humans == effective barrier to species migration
       Problem: old ecological communities disrupted + impeding species migration halted


        17                                                           7/1/2011
Ecological responses to recent climate
change (Walther et al 2002)
    There is now ample evidence of the ecological impacts of
     recent climate change, from polar terrestrial to tropical
     marine environments. The responses of both flora and
     fauna span an array of ecosystems and organizational
     hierarchies, from the species to the community levels.
     Despite continued uncertainty as to community and
     ecosystem trajectories under global change, our review
     exposes a coherent pattern of ecological change across
     systems. Although we are only at an early stage in the
     projected trends of global warming, ecological responses
     to recent climate change are already clearly visible.


    18                                         7/1/2011
Extreme ends…




19              7/1/2011
20   7/1/2011
Coral bleaching in tropical seas
    Most noticeable
    Already near their upper thermal limits – mass bleaching
     events have taken place whenever sea temperatures have
     > long-term summer average by more than 1 degree
    6 periods of bleaching between 1979 and 2002 –
     increasing in # and intensity
    1998: 16% of world’s reef-building corals died




    21                                        7/1/2011
Arctic lakes
    1997 - 2004: decline of 1170 large lakes (> 40 ha); 11%
    Total regional lake surface area decreased by 6% (93 000
     ha); 125 lakes vanished;
    Northerly lakes increasing in size – by 12% (13 3000 ha)
        Increased precipitation in the north
        Southerly declines in lake area have outpaced northerly gains in
         lakes
        The more southerly permafrost soils  no longer permanently
         frozen  allow lakes to rain




    22                                                 7/1/2011
Mountain snow and ice
    Note: mountain snowpacks affect quantity and timing of water in streams
     supplying ecosystems in surrounding lowlands
    Nearly all mountains of sufficient height on Earth have snow caps
    Those will be reduced in volume – especially at lower latitudes
        Smaller mountain snow caps may be seasonally thicker due to extra precipitation
    Already happening – at lower and mid latitudes (China, N.A. and Europe)
    Plus: snow-cap melt run off will shift away from summer and fall when
     biological (and human) demand for water is greatest compared to winter
     and early spring
        Annual cycle of water supply for many terrestrial and human systems will see
         reduced temporal buffering
        1/6th of the human population relies on glaciers and seasonal snowpacks for
         water supply
        Over 50% of river flow dominated by snow melt in: all of Canada, NW states of
         US, all of Scandinavia (exc Denmark) Balkan Europe, Russia, NE China, much of
         Chile, SW Argentina and S of New Zealand



    23                                                            7/1/2011
Water and ice
    In terms of human # - most critical region: China and
     parts of India
    Supports 2 billion people
    Largest volume of ice outside of polar and peri-polar
     regions
    Nearly 70% of the Ganges’ summer flow and 50-60% of
     other of the regions’ major rivers: melt water




    24                                       7/1/2011
Details. Details. Complexity in details.
    Global warming  far fewer areas of snow cover  does
     act to reduce carbon loss from soils around the margins
     of snowfields
        Mountain areas of thin snow cover tend to be ecotones –
         special biological communities in border areas between two
         habitat types
        Given that biological communities migrate and change (more
         so with CC) – ecotones are v sensitive
        Carbon in soils can either accumulate or be released –
         depending on climate and climate change
        Areas of thin snow cover are less insulated from the cold 
         affects the rate of carbon release from soil. How?

    25                                               7/1/2011
Winter forest soil respiration controlled by climate and
microbial community composition (Monson et al, 2006)
    Most terrestrial carbon sequestration at mid-latitudes in the
     Northern Hemisphere occurs in seasonal, montane forest
     ecosystems
    Winter respiratory carbon dioxide losses from these
     ecosystems are high, and over half of the carbon assimilated by
     photosynthesis in the summer can be lost the following winter
    The amount of winter carbon dioxide loss is potentially
     susceptible to changes in the depth of the snowpack; a
     shallower snowpack has less insulation potential, causing
     colder soil temperatures and potentially lower soil respiration
     rates.
    Recent climate analyses have shown widespread declines in the
     winter snowpack of mountain ecosystems in the western USA
     and Europe that are coupled to positive temperature
     anomalies

    26                                             7/1/2011
Winter forest soil respiration controlled by climate and
microbial community composition (Monson et al, 2006)
    Here we study the effect of changes in snow cover on soil carbon cycling
     within the context of natural climate variation.
    We use a six-year record of net ecosystem carbon dioxide exchange in a
     subalpine forest to show that years with a reduced winter snowpack are
     accompanied by significantly lower rates of soil respiration.
    Furthermore, we show that the cause of the high sensitivity of soil
     respiration rate to changes in snow depth is a unique soil microbial
     community that exhibits exponential growth and high rates of substrate
     utilization at the cold temperatures that exist beneath the snow.
    Our observations suggest that a warmer climate may change soil carbon
     sequestration rates in forest ecosystems owing to changes in the depth of
     the insulating snow cover.
    Decreases in the winter snow pack will generally cause decreases in the
     loss of respired carbon dioxide from soils of forest ecosystems – thus
     enhancing the potential for soil carbon sequestration
    A warmer climate may change the beneath-snow soil temperature in forest
     ecosystems because of changes in the depth of the insulating snow cover,
     changing soil respiration rates, and soil C sequestration rates

    27                                                    7/1/2011
    Thus far: discussed change observed
    Further change is anticipated with further warming
    IPCC scientific consensus
        Warming will continue through the rest of the this century and
         beyond
        Questions: how much warming and at what rate
        Depends on future emissions of GHG
    Future species migration and other climate-related
     biological impacts will continue beyond those already
     seen


    28                                               7/1/2011
    What if species have nowhere to migrate to?
   Species migration: complex and difficult in a modern landscape highly fragmented by human
    management and land use; Critical to level of extinction if species’ thermally determined spatial
    range becomes restricted and reduced to nothing
   Typically: at high-latitude margins of continents
        A terrestrial species in Eurasia migrating northwards as the climate warms will reach the edge of the
         continent. – nowhere to go
   Polar bears
        Evolved from a group of brown bears stranded by glaciers
        Speciated rapidly, evolving sharper canine teeth (less vegetation), longer neck (for swimming) larger paws
         (for spreading weight on ice and swimming), and thicker fur lighter in color
        Require ice platforms from which to hunt: Arctic ice is reducing quickly. 1 estimate: 7% reduction in 25 years
         and 40% loss of thickness
        Top of the food chain; some seal populations have increased  affecting fish predation
   Walrus
        Have to work harder to find food due to there being less ice. Walrus mothers nurse their young on sea-ice
         floes
        Of the 3 walrus species, population living in the Russian Arctic has the smallest population – between 5 –
         10,000
   Emperor penguin
        Breeding population declined abruptly in the late 1970s to 50% of former level –
        Decline in Antarctic krill  less winter ice



        29                                                                               7/1/2011
   Global warming thermally determined                    Tops of
    zonation on mountains changes and rises                mountains…
        Cannot migrate above mountain summits
   Alpine biome is 3% of the vegetated
    terrestrial surface – and shrinking
        Ural Mountains
            Temperatures risen by more than 4 C in 20th
             century
            Tree lines have risen between 20 and 80 m
             upslope
            Reducing regional alpine lines by 10 – 20%
   Mountain pygmy possum (S-E Australia)
        Habitat favored by skiers
        Under serious threat



    30                                                     7/1/2011
                                                     Highland forests of
   20 species of 50 anurans (frogs and              Monteverde, Costa
    toads) in a 30 km2 study area went               Rica
    extinct – including endemic golden
    toad (1987)
   Population crashes all associated with
    decline in dry-season mist frequency –
    due raising of cloud-bank base
    (presumed)
   Changes behavior of animals
        Harlequin frogs gathered near waterfalls
          increased change of attack by parasitic
         flies  increased mortality
   Population crashes due constellation of
    demographic changes linked to
    regional climatic warming

    31                                               7/1/2011
‘A message from the frogs’ – Blaustein and Dobston
(Nature 2006)
    The harlequin frogs of tropical
     America are at the sharp end of
     climate change. About two-thirds of
     their species have died out, and
     altered patterns of infection because
     of changes in temperature seem to be
     the cause.
    Climate change has already altered
     transmission of a pathogen that affects
     amphibians – leading to widespread
     populations and extinctions
    67 % of the 110 species of harlequin
     frogs endemic to the region have died
     in past 20 years
    78-83% of extinctions occurred in
     unusually warm years in the tropics
    Shifting temperatures are the ultimate
     trigger for the expansion of a
     pathogenic fungus


    32                                         7/1/2011
More climate and disease
    Mountain pine beetle                 Mountain Pine Beetle
        Warmer climate conditions         and Forest Carbon in
         allow the mountain pine           BC
         beetle to complete its life      Mountain Pine Beetle:
         cycle in 1 year rather than
                                           A Climate Change
         2 years
                                           Catastrophe




    33                                              7/1/2011

								
To top