Climate change and the future of the Great Barrier Reef. Ove Hoegh - - PowerPoint PPT Presentation

Climate change and the future

• f the Great Barrier Reef.

Ove Hoegh‐Guldberg

Global Change Institute ARC Centre for Excellence for Coral Reef Studies for Coral Reef Studies The University of Queensland www.coralreefecosystems.org www.climateshifts.org

1975 1975 1981 1981 2004 2004

M lti l Multiple‐use Gold standard

Andrew Elliott – May 24 1994 Photos compiled by David Wachenfeld, Great Barrier Reef Marine Park Authority

Great Barrier Reef: Great Barrier Reef:

Changes in hard coral cover from

Is coral cover decreasing? Is coral cover decreasing?

Changes in hard coral cover from 1980-83 to 2000-2003 Bruno and Selig 2007, PLoS ONE 2 Bellwood et al 2004 Nature 429: 827-833 Sweatman et al. 2010 - Changes in hard coral cover on the GBR - (fixed sites) 1993-2007

?

McCulloch et al. 2003 (Nature, 421: 727‐730

• M. Devlin, James Cook University & RRRC 2011

Mass coral bleaching

GBR 2006 STRESS

STRESS STRESS

Mass Bleaching Events

H h H h G ldb (1995) G ldb (1995) Hoegh Hoegh‐Guldberg (1995) Guldberg (1995) Extensive experimental evidence

1998 2002 Small changes in sea temperature explained patterns of mass bleaching and mortality 1998 2002 T anomalies >50% >50% T X exposure time

16% of the world’s l di d i 1998

1998: DHW

corals died in 1998

Bleaching Severe Bleaching Mass Mortality

Australian Bureau of Meteorology

Sea temperatures are increasing steadily within the Coral Sea. While we have been lucky so far, other regions like the , g Caribbean have not

Worst bleaching ever Caribbean – predictive tools indicate rising stress levels Spillman et al. 2011 (American Meteorological Society)

2010 – the hottest year on the instrument record

Tobago, Caribbean 2010 Global temperature Hansen, et al. 2010

• Rev. Geophys.,

accepted. accepted. Summer DHW values in 2010

Great Barrier Reef E trapolating from the past 20 ears to the f t re Extrapolating from the past 20 years to the future

?

Threshold temperature – above which bleaching and mortality occur

WHAT DOES THE FUTURE HOLD?

Hoegh-Guldberg (1999) – Trajectories based on IS92A (doubling of CO2 by 2100)

Crucial question: Could corals evolve fast enough to keep up with climate change?

IF SO, THEN NO PROBLEM!

Issues Issues

ure (oC) Physiological threshold ,

Issues

• Corals tend to have

Issues

• Corals tend to have

Temperatu

– Long generation times (5‐100 years) – Low diversity populations – Long generation times (5‐100 years) – Low diversity populations

Sea T

• Not bacteria or even Drosophila!
• Not bacteria or even Drosophila!
• Evolution likely to be slow rather than fast
• Evolution likely to be slow rather than fast

Hoegh‐Guldberg (1999)

Could corals migrate their Could corals migrate their way out of trouble? way out of trouble?

30oC 27oC

Coral reefs would have to move at the rate of at least 15 km per year!

Swapping your symbionts to increase your temperature tolerance?

Great idea: any evidence? Great idea: any evidence?

Stress Repopulate

Completely new symbiont established ‐

Great idea: any evidence?

No change: Michael Stat

Great idea: any evidence?

No change: Michael Stat

Bleach higher temperature tolerance

K’le Gomez‐Cabrera Eugenia Sampayo How many more??? K’le Gomez‐Cabrera Eugenia Sampayo How many more???

Co‐evolution of host and symbiont

Within species Between species

• typye

Deep Shallow biont geno Shallow Symb Host genotype

Seriatopra hystrix Li ard Island Lizard Island Bongaerts P, Ridgway T, Riginos C, Englebert N, Sampayo E Vermeulen LaJeunesse, Hoegh‐Guldberg, Schmidt, Fitt (2003) Sampayo E, Vermeulen F, Hoegh-Guldberg O (2010)

Ocean Acidification

Hoegh‐Guldberg et al. 2007 Science

ns ns CO3

2‐

Fraction Fraction

3

Log F Log F

CO3

2‐

7.6 7.8 8.0 8.2 7.6 7.8 8.0 8.2

pH pH

• K. Anthony

Today Paleo‐reconstructions (2) from boron isotopes in foraminifera atmosphere–ocean– sediment carbon cycling model

Pelejero, Calvo and Hoegh‐Guldberg (2010)

Impacts on coral calcification: Kleypas and Langdon (2006)

All negative g 1, 4, 5 => adjusted using CO2 Range per unit decrease in aragonite saturation:

5‐38% decrease (~ 17%)

Note: 1 unit decrease in aragonite g saturation ~ 140 ppm increase in atm CO2 Double CO2 ~ 280 ppm

Is a decrease of 5‐38% with a doubling

• f CO2 going to change m ch?
• f CO2 going to change much?

Reef accretion

Coral growth

ee acc e o

(10‐300 mm/year) Reef growth (1 3 mm/year) (1‐3 mm/year) Davies (1985)

n sion sion icatio icatio

Carbonate balance of reefs is all important

Ero Ero Calcifi Calcifi C

Ocean acidification and aragonite saturation Ω Ωarag

arag

Hoegh-Guldberg et al. 2007 (Science Vol 318)

3.3 (limit for carbonate coral reefs)

Other factors Other factors

Storm damage Storm damage Coastal run Coastal run‐ ‐off

• ff

Coasta u Coasta u

• (esp

esp after drought) after drought)

Annual calcification rate of 328 long‐lived corals

1990 1990

De’ath et al. 2009

15% decrease since 1990 (no other in 400 yrs of record)

$6 billi / $6 billi / $6.5 billion/year $6.5 billion/year 63,000 jobs 63,000 jobs 1 million species 1 million species 1 million species 1 million species

8 e, v. 31 Scienc

• al. 2007

erg et a ‐Guldbe Hoegh‐

The future of coral reefs? The future of coral reefs?

Hoegh‐Guldberg et al. 2007 (Science) g g ( ) 387 ppm 450 ppm >500 ppm +1.0oC +2oC > +2oC

What does this mean for GBR industry and communities?

Tourism plays a major role in earnings of five Great Barrier Reef regions (differ in relative importance) Barrier Reef regions (differ in relative importance)

83% of economy depends on depends on reef‐related earnings

What if the GBR were no longer

Hoegh‐Guldberg and Hoegh‐Guldberg (2004) www.wwf.org.au/publications/ClimateChangeGBR.pdf

were no longer ‘great’?

What will it take What will it take t th GBR? t th GBR? to save the GBR? to save the GBR?

The significance of 450 ppm d th 2°C d il? and the 2°C guardrail?

Implications: 1 000 GT f C b 1,000 GT of Carbon dioxide left to emit (emit 30‐40 GT per year at present) Clock started in

GBR gone?

2000: only 700 GT left to emit

GBR increasingly damaged by T, pH

g Meinshausen et al. 2009 (Nature 458, 1158‐1162)

700 GT CO2 left to emit

2 (for a 60% chance of remaining below 450 ppm)

Is still ‘Great’ Vast economic engine Vast economic engine Globally valued 1 E t li t h th t

• 1. Extreme climate change threat
• 2. Reef is not adapting fast enough

3 Major risk to people and industry

• 3. Major risk to people and industry
• 4. 450 ppm and +2°C guard‐rail

critical to GBR survival

• 5. Managing local factors will get

more not less important