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Impacts of CC
Section 2 – reading is at the bookstore
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But first
 Climate Change conference began yesterday
 Check it out
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And second
Your paper
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And Third
Field work on cc and gender
… interested?
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Consequences of
climate change
“In nature, there are neither rewards nor
punishments – there are consequences.” –
Robert Ingersoll, 1833-1899
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Geological consequences
 Is it possible to unravel the climatic factors from
other causes of geological change?
 Climatic events – waxing and waning of ice
sheets, desiccation of continental interiors, drying
up of oceans – had major impacts on the
geology of the large parts of the Earth
 Question: were they ‘cause’ or ‘effect’?
 If ‘effect’ of plate tectonics and volcanism…
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2 issues
 Do shifts in the climate exert a significant feedback on tectonic
activity (eg volcanism) by – say – changing the load on the
Earth’s crust due to the build-up and collapse of polar ice sheets
or changing sea levels?
 If the climate can exert influence on tectonic activity, is it
affected by extraterresrial effects (such as?)?
- No agreement currently on whether climate change exerts a
significant effect on tectonic activity
- But – significant evidence to suggest there are various ways in
which climate might create/help relieve stresses in the Earth’s
crust
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Stresses in the Earth’s crust…
 Example: during the last ice age, the eruption of volcanoes in the
Med occurred more often at times of rapid sea-level change
 Proposition: changes in the loading of the Earth’s crust by the buildup and collapse of ice sheets over northern Europe did influence
the level of volcanic activity in the region
 Unclear: how this feeds back into climate change
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Variations in the day
 More subtle global effect: variations in the length of the day
 If atmosphere circulates more rapidly, principle of the
conservation of angular momentum requires that the Earth
should slow down – an ever so tiny amount – to
compensate for this atmospheric acceleration
 due to a major ENSO warming event – equatorial winds
speed up and Earth slows down
 During sudden changes of the climate  Earth could speed
up or slow down by significant amounts  could set up
stresses and strains in the crust  lead to increased volcanic
activity  more climate changes
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Climate change ->
volcanoes?
 Was a big question during the Iceland volcano –
April 2010
 “Iceland's Eyjafjallajokull has everyone discussing
what causes volcanic eruptions. One controversial
hypothesis suggests climate change may play a
role” http://theweek.com/article/index/202085/does-globalwarming-cause-volcanoes-to-erupt)
 Melting ice could provoke large eruptions…If Iceland's ice
caps thaw, their weight diminishes, "freeing magma from
deep below ground." Heavily ice-capped volcanoes like
those in the Aleutian islands of Alaska or Patagonia in South
America could be most at risk.
 But Volcanic activity is caused by "magma rising to the
surface, not glaciers melting”
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Extreme weather events
 “One swallow a spring does not make, and so a
single extreme weather event does not
necessarily signify climate change. But how
many swallows do?”
 Recent years: increasing frequency of strong
hurricanes; total # same
 Recent years: record-breaking warmth
 Recent years: local and regional unusual intense
rainfall and drought
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 A warmer world  more thermal energy within the atmosphere
and ocean-circulation system  some of that energy  greater
evaporation (more rainfall) and wind speeds and storm size
 Therefore: as the world warms, so the frequency of extreme
weather events is likely to increase
 What of the intensity and frequency of heat waves? (strong
psychological factor) Also likely to increase. Heat waves over parts
of US and Europe coincided with a specific atmospheric
circulation pattern that is intensified by ongoing increases in
greenhouse gases
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Hotter?
 Expect more extreme weather events
 But not all extreme weather events are attributable to CC
 Need to know: what is expected with natural variability
assuming no carbon dioxide forcing and with climate forcing
from additional anthropogenic greenhouse gases
 UK HadCM3 model: an exceptionally warm summer up to 2020
will become a normal summer by the 2040s in Europe … they
projected an increase 100-fold over the next four decades
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Wild species / flora and
fauna
 Given that:
 Climate is a primary driven of biotic system
 Climate plays a central role in determining which
types of species inhabit which parts of the world
 The rate of warming is expected to continue to
increase – increasing by a minimum of 1.1 to
potentially 6.4 degrees C or more
 Expectation is…
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What we know
 Plants and animals survived the less-rapid warming of the post-Ice
Age transition by shifting their ranges poleward and up in
elevation, similar to the range shifts we have witnessed recently
 Many species have begun to move – moving poleward; blooming
earlier
 What we have now
 Rapid temperature change
 In addition to everything else (such as?)
 “the combined effects of rapid temperature increases and other
anthropogenic changes collectively affect the flora and fauna of our
planet more strongly – synergistically – than if each of these
disturbances occurred alone.”
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Flora…
 Thermal growing season (TGS) could be extended due to
current warming
 Why?
 More days in the year in which plants can grow
 Primary biological productivity increases
 More carbon dioxide sequestered
 More water consumption (in addition to more water
consumption due to climate warming itself)
 Water demand depends on water supply – may have more
rainfall, or less, depending on region and locale
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Flora…
 Consider a species that is on the border of its environmental
range
 One environmental factor may increase (temp) – does not
mean that other environmental factors will increase (rain) to
accommodate a species’ healthy growth
 Even if more precipitation – still – expect more evaporation
 In some places and for some species whose environment
has changed, water availability could be a problem
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Alaskan White Spruce
(Picea glauca)
 Thermal growing season (TGS) extended due to current
warming – yes
 But – growth not increased
 Why: temperature-induced drought stress
 Interior of Alaska is semi-aird and in many places the potential ET
= annual P
 Increase potential ET through TGS and…
 P. glauca is one of the most productive and widespread
forest tree species in the boreal forest; plays important roe
in northern-hemisphere terrestrial sink!
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Tropical-rainforest
 A two decade long study (2004): of 18 tropical rainforest plots that
were otherwise disturbed [study online]
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All trees over 10 cm in DBH were tagged
Nearly 13,700 recorded
Analysis done on genus level (due to high diversity)
244 genera – 115 used for statistical analysis
 Within the plots, the rates of tree mortality, recruitment and growth
have all increased
 No increase in pioneer species
 Increasing number of faster-growing trees
 Decline in slower-growing trees
 What is causing these changes?
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What is causing these
changes?
 Previous disturbance unlikely
 Due to regional climate cycles – El-Nino related droughts which have
increased over the last century? [two other analyses say no]
 Rainfall changes (not drought) – i.e. decline in rainfall, river flow and
ground water – also discounted and rejected
 Accelerated forest productivity – due to increased carbon dioxide – or
due to increased cloudiness and higher airborne nutrient transfer from
increased forest fires (both climate-related factors)
 Greenhouse gases the spur
 These changes: local and global implications
 Carbon sinks? – increases in carbon storage by tropical trees may be
slowed by the tendency of canopy and emergent trees to produce
wood of lower density as their size and growth rate increases
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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?
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 A biologist (Parmesan) and an economist (Yohe)
studied this issue
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"A Globally Coherent Fingerprint of Climate Change Impacts
across Natural Systems"
Friday, January 31, 2003
GARY W. YOHE
WESLEYAN UNIVERSITY
CAMILLE PARMESAN
UNIVERSITY OF TEXAS - AUSTIN