Transcript CO 2 and global temperature

Climate Change &
Biodiversity
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CO2 and global temperature
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1.0
Cape Gr im and South Pole
Law Dome ice cores
temper ature c hange
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0.5
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0.0
-0.5
1000
CO2 (ppm)
o
temperature ( C)
Carbon dioxide and temperature last 1000 years
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800
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years before 2000 AD
• CO2 increased 35% since industrial revolution
• Exceeds natural range over past 650,000 yrs
• 0.8oC increase in global average temperature since 1906
• Rate of warming doubled in past 50 years
• 1990s warmest decade, 1980s second warmest
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Northern Hemisphere Ice
• Arctic ice: shrinking 7.8% per
decade (3 x faster than GCM
projections), historic low in 2007,
20% below previous record (2005)
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Muir Glacier, Alaska
1941
2004
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What about the future?
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But:
• CO2 has almost tripled since the 1990s from 1.1% pa to 3.1% in
the 2000s
• Sea levels also rising faster than IPCC projections
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Global Temperature Projections
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Australian trends
• Temperatures increased 0.9oC since 1950
• Frequency of hot days and nights increased
• Recent droughts hotter
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2005: Warmest year on record
(>1oC above long-term average)
2007: Warmest year on record in southern Australia, 6th warmest overall
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Australian trends
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Rainfall very variable
Decreased along east coast and SW WA
Increased in north west
Snow depth declined 40% since 1960s
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What do we expect in Australia?
• Temperature will increase:
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+ 1oC by 2030
+ 0.8-2.8oC by 2050
+ 1-5oC by 2070
Rainfall will change
– Little change in north
– Decrease of 2-5% elsewhere by 2030
Further declines in snow
Increased drought, especially in SW
Increase in fires
Sea level will rise
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Natural ecosystems and biodiversity
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Species & communities will be affected
1. Directly:
Temperature
Rainfall
CO2
Extreme events
2. Indirectly:
Interactions with other species
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Increased temperature
Will affect:
• Photosynthesis
• Respiration
• Decomposition
• Metabolic rate
• Survivorship
• Timing of life cycles
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Indirect Impacts
e.g. Herbivory
Increased CO2
Reduced C:N
• Increased consumption
• Reduced survival & reproduction
• Increased development time
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Winners
• Short generation times
• Good dispersal
• Broad climatic tolerances
• Generalists
• Opportunists
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Losers
• Long generation times
• Poorly dispersed
• Narrow climatic tolerances
• Specialists
• Large home ranges
• Isolated populations
• Genetically impoverished
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What do we expect?
Some species will move:
eg.
• away from current cold boundary
• south
• up
BUT:
Some species will lose much of
their current habitat
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Observed changes
• Southward range expansions observed for several bird species
eg: Figbird, Channel-billed cuckoo, Black-necked Stork and Pied
Heron, Noisy Pitta, Pacific Baza, Beach Thick Knee, Hooded
Plover
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Grey-headed Robin
Present
+ 1 deg.
86%
+ 3.5 deg.
7%
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Lemuroid Ringtail Possum
Present
+ 1 deg.
46%
(Williams et al. 2003)
+ 3.5 deg.
0%
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What do we expect? (cont)
Advances in life cycles
eg earlier flowering, fruiting, egg laying, migration
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Since 1960:
Migratory birds arriving 3.5 days per decade earlier
& departing 5.1 days per decade later
Beaumont et al. 2006
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Most at risk..
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Alpine zone
Coastal wetlands
Freshwater wetlands & rivers
North QLD Wet Tropics
South-west WA
Coral reefs
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Alpine zone
• < 0.15% of land surface
• Low altitudinal relief
• Many species already threatened
• 40% reduction in snow cover and
duration since 1960s
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Duration of snow cover,
Australian Alps
Modelled current
Moderate climate
change : 0.3oC
increase
More severe climate
change : +1.3oC
increase, -8%
precipitation
www.greenhouse.gov.au
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Predicted impacts
eg Burramys parvus, mountain
pygmy possum, < 500
individuals, confined to 10 km2
habitat
• Dependent on snow cover
for hibernation
• Bioclimate projected to
disappear with 1oC warming
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Coastal wetlands
• Already experienced major losses
in area
• Vulnerable to sea level rise, tidal
surges and changes in
precipitation
• Ongoing reductions in saltmarsh
communities (up to 80% area in
some locations)
• Some mangrove communities
extending landwards
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Northern Territory rivers
• Mangroves encroaching on freshwater wetlands
- associated with sea level and rainfall changes
- 17,000 ha freshwater wetlands replaced by 4 km
intrusion of mangroves in Mary River system, since 1940s
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Freshwater wetlands & riverine environments
• Already severely degraded
• Will be affected by further reductions in flows if rainfall
declines concurrently with warming
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Wet Tropics World Heritage Area
Temperature
increase (oC)
No. species losing core
climatic habitat
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3.5
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Coral Reefs
• 1998: highest SSTs on record
• Feb-April 1998: most severe &
widespread bleaching on
GBR so far
• Unmatched in period
1903-1999
• By 2030, bleaching may occur
annually
• Potential replacement of coral by algal
communities
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Conclusions
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Climate change is already here
Plants and animals are already responding
We need to:
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Drastically reduce our greenhouse gas
emissions
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Think about how to help species and
ecosystems adapt to inevitable change
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