J.E.N. Veron

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The Royal Society, 6th July, 2009
Is the Great Barrier Reef on Death Row?

• J.E.N. Veron

• J.E.N. Veron

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Coral reefs are unique...
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1. They exist at the interface of atmosphere and
ocean
physically and chemically stressful
4
2. They are geological structures made by living
organisms
5
Corals are closely attuned to their environment
Light
Temperature
31ºC
Carbonate chemistry of the ocean
6
Reefs are Natures historians
They are record-keepers of ancient fauna
and of ancient environments
and of modern environments
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Todays subjects
Carbon dioxide
Temperature
Sea-level changes
8
Mass extinctions
Reefs lead a boom-to-bust existence ....
and they bust easily
Palaeozoic
Cenozoic
Mesozoic
9
Palaeozoic
Mesozoic
Cenozoic
10
Palaeozoic
Mesozoic
Cenozoic
11
Palaeozoic
Mesozoic
Cenozoic
12
Palaeozoic
Mesozoic
Cenozoic
13
Palaeozoic
Mesozoic
Cenozoic
14
Palaeozoic
Mesozoic
Cenozoic
15
Palaeozoic
Mesozoic
Cenozoic
16
Palaeozoic
Mesozoic
Cenozoic
17
Palaeozoic
Mesozoic
Cenozoic
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Silurian
Permian
Triassic
Jurassic
Cretaceous
Ordovician
Devonian
Carboniferous
Palaeozoic
Mesozoic
Cenozoic
490
434
410
354
298
251
205
141
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Millions of years ago
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6,000
?
5,000
?
?
4,000
?
CO2 (ppm)
?
?
3,000
?
?
2,000
?
1,000
Permian
Triassic
Jurassic
Cretaceous
Devonian
Carbonif.
Silurian
Ordovician
Palaeozoic
Cenozoic
Mesozoic
500
400
300
200
100
0
Millions of years ago
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6,000
?
5,000
?
?
4,000
?
CO2 (ppm)
3,000
?
?
?
2,000
?
1,000
Permian
Triassic
Jurassic
Cretaceous
Devonian
Carbonif.
Silurian
Ordovician
Palaeozoic
Cenozoic
Mesozoic
500
400
300
200
100
0
Millions of years ago
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Causes of mass extinctions
1. Causes independent of the carbon cycle
2. Causes linked to the carbon cycle
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• 1. Causes independent of the carbon cycle

Asteroid impacts
Nuclear winters
Sea-level changes
Low temperature
High temperature
High temperature
Disease and toxins
Extraterrestrial events
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• 1. Causes independent of the carbon cycle

Asteroid impacts
Nuclear winters
Sea-level changes
Low temperature
High temperature
Disease and toxins
Extraterrestrial events
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Todays subjects
Carbon dioxide
Temperature
Sea-level changes
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K/T
Pleistocene
Palaeocene
Eocene
Oligocene
Miocene
Pliocene
65
55
38
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5.3
2.6
Silurian
Permian
Triassic
Jurassic
Cretaceous
Ordovician
Devonian
Carboniferous
Palaeozoic
Mesozoic
Cenozoic
490
434
410
354
298
251
205
141
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Millions of years ago
26
K/T
Late Palaeocene Thermal Maximum
4000
Mid Eocene Extinctions
3000
CO2 (ppm)
2000
Origin of the GBR?
1000
Not much information
0
Palaeocene
Eocene
Oligocene
Miocene
Pliocene
65
55
38
24
5.3
2.6
Millions of years ago
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360
320
Last interglacial
280
CO2 (ppm)
240
200
400
300
200
100
0
Thousands of years ago
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Today 387
360
320
Last interglacial
280
CO2 (ppm)
240
200
400
300
200
100
0
Thousands of years ago
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Past 420,000 Years - Vostok Ice Core Data
400
350
CO2
Glaciations
300
250
200
150
-5
5
-10
0
IGBP 2000
Temperature Anomaly
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Late Palaeocene Thermal Maximum
Mid Eocene Extinctions
C

5
Present
-5
Pleistocene
Palaeocene
Eocene
Oligocene
Miocene
Pliocene
65
55
38
24
5.3
2.6
Millions of years ago
31
Last interglacial
4
2
Present
0
-2
C
-4
-6
-8
400
300
200
100
0
Thousands of years ago
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m
40
Last interglacial
Present
0
-40
-80
-120
400
300
200
100
0
Thousands of years ago
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Last interglacial
Present
0
GBR flooded
Last glacial maximum
-50
-100
120
80
40
0
m
Thousands of years ago
40
Last interglacial
Present
0
-40
-80
-120
400
300
200
100
0
Thousands of years ago
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The GBR reef
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The GBR savannah
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At the time of Australias first people
Todays sea level
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Home sweet home?
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Todays subjects
Carbon dioxide
Temperature
Sea-level changes
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Corals live in symbiosis with zooxanthellae
Temperature stress
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600 year-old Porites colonies
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2100
900
320
No harm to reefs in the long term?
800
Worst-case scenario
CO2 (ppm)
700
Mid-range scenario
600
2050
500
400
2000
1990
320
1950
1900
1850
300
1800
1750
Date
48
2100
900
350
Periodic mass bleaching on the GBR
800
Worst-case scenario
CO2 (ppm)
700
Mid-range scenario
600
2050
500
400
2000
350
1990
1950
1900
1850
300
1800
1750
Date
49
2100
900
387
(Today)
Compounding long-term degradation for GBR
800
Worst-case scenario
CO2 (ppm)
700
Mid-range scenario
600
2050
500
400
2000
1990
1950
1900
1850
300
1800
1750
Date
50
2100
900
400
Will be reached by 2015
Will cause major weather events
800
Worst-case scenario
CO2 (ppm)
Will cause severe bleaching, mainly during El
Niño cycles
700
Mid-range scenario
600
2050
500
2000
1990
1950
1900
1850
300
1800
1750
Date
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2100
900
450
Will be reached by 2030-2040?
Will cause severe bleaching most years
800
Worst-case scenario
CO2 (ppm)
700
Mid-range scenario
600
2050
500
400
2000
1990
1950
1900
1850
300
1800
1750
Date
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2100
500
900
Will result in a global increase of gt3C
Will cause severe bleaching every year.
800
Worst-case scenario
CO2 (ppm)
700
Mid-range scenario
600
2050
400
2000
1990
1950
1900
1850
300
1800
1750
Date
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2100
900
550
Will result in 2.8 - 5.8C warming
800
Worst-case scenario
CO2 (ppm)
700
Mid-range scenario
600
2050
500
400
2000
1990
1950
1900
1850
300
1800
1750
Date
54
Carbon dioxide
Temperature
Sea level
Arctic ice
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Cyclones
El Niño
Thermal cap
Ocean conveyor
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Source Hoegh-Guldberg et al., 2007
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2100
900
800
Worst-case scenario
CO2 (ppm)
700
Mid-range scenario
600
2050
500
400
2000
1990
1950
1900
1850
300
1800
1750
Date
58
2100
900
800
Worst-case scenario
CO2 (ppm)
700
Mid-range scenario
600
2050
500
400
2000
1990
1950
1900
1850
300
1800
1750
Date
59
2100
900
800
Worst-case scenario
CO2 (ppm)
700
Mid-range scenario
600
2050
500
400
2000
1990
1950
1900
1850
300
1800
1750
Date
60
2100
900
800
Worst-case scenario
CO2 (ppm)
700
Mid-range scenario
600
2050
400
2000
1990
1950
1900
1850
300
1800
1750
Date
61
2100
900
800
Worst-case scenario
CO2 (ppm)
700
Mid-range scenario
600
2050
500
400
2000
1990
1950
1900
1850
300
1800
1750
Date
62
2100
900
800
Worst-case scenario
CO2 (ppm)
700
Mid-range scenario
600
2050
500
400
2000
1990
1950
1900
1850
300
1800
1750
Date
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Todays subjects
Carbon dioxide
Temperature
Sea-level changes
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1980
Mass bleaching started
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Today
Mass bleaching mostly during El Niño events
Starting to occur during non-El Niño years
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Synergies 25 years from now
Mass bleaching most years
Very extensive habitat destruction
Extinctions start
Coralline algae calcification marginal
Stepwise decline
Biodiversity reduction
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Synergies 50 years from now
gt600 ppm Oaragonite 3 ? 4.5 ºC
gt600 ppm Oaragonite 3 ? 4.5 ºC 400 mm
gt600 ppm Oaragonite 3 ? 4.5 ºC 400 mm
gt600 ppm
gt600 ppm Oaragonite
None shallower than 10 m
Calcification marginal
Extinctions extensive
No shallow-water habitats
No coralline algae
Physical impacts sea-level rise, super-cyclones
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Synergies 75 years from now
Corals gone or askeletal
Molluscs in sharp decline
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100 years from now
Corals extinct or askeletal
All other taxa going extinct
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CO2 in summary
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But the eel didnt realise...
...the size of the problem
...the domino effect
...ecosystem failures are mass extinctions
...that 450 ppm will bring on the demise of the
GBR
320 - 350
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j.veron_at_coralreefresearch.com
www.zsl.org/coralcrisis
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The views expressed in this presentation are my
own
The authors of 3000 peer-reviewed publications
Over 1000 colleagues
The Great Barrier Reef Marine Park Authority
Australian Coral Reef Society
International Society for Reef Studies
A host of research organisations, and
now the global network of science academies
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Thank you for listening