Climate change and tropical coastal

ecosystems

Ove Hoegh-GuldbergGlobal Change Institute

University of Queensland

Climate changeClimate change

EcosystemsEcosystems

PeoplePeople

Centre of Biodiversity• Corals (>76%), mangroves (>70%)• Seagrass (>70%), Reef fish species (37%)• Epicentre of most marine organisms

100 million people living coastally• Coastal resources are all important

300 page report : www.panda.org/wwf_news/?164062/

Tropical coastal resources are critical to 100 million yet are severely threatened.

Local factors• Water quality• Over-fishing• Physical destruction

Global factors• Ocean warming• Acidification• Sea level rise• Storm intensity

Sea grassSea grass

Coral reefsCoral reefs

MangrovesMangroves

Coastal resources provide:

•Food• Income• Building materials• Coastal protection

•Wave energy•Storm/tsunami impacts

• Coastal stability• Traditional medicines• Bio-discovery• Cultural importance

Loss so far: 30-50%. Coral reefs are declining at

1-2% per year(Bruno and Selig 2007)

Peñaflor et al., Coral Reefs in press; permission of Springer Science and Business Media

The waters of the Coral Triangle are rapidly warming and acidifying

NOAA

Up to 3-4oC per century(1-2oC is too much)

Need blue conditions to maintain carbonate

coral reefs

ppm

ppm

ppm

PLUS sea level rise

Tropical coastal resources are critical to 100 million yet are severely threatened.

Local factors• Water quality• Over-fishing• Physical destruction

Global factors• Ocean warming• Acidification• Sea level rise• Storm intensity

Sea grassSea grass

Coral reefsCoral reefs

MangrovesMangroves

Coastal resources provide:

•Food• Income• Building materials• Coastal protection

•Wave energy•Storm/tsunami impacts

• Coastal stability• Traditional medicines• Bio-discovery• Cultural importance

Loss so far: 30-50%. Coral reefs are declining at

1-2% per year(Bruno and Selig 2007)

XX

• 50% of current ecosystems by 2050• <5% of current ecosystems by 2100• Food harvested (protein)

– 50% by 2050– 5% by 2100, continues to erode

• Management of local threats makes no real difference ...

• 50% of current ecosystems by 2050• 30% of current ecosystems by 2100• Food harvested (protein)

– 50% of today by 2050– 30% of today by 2100 but rebounds

• Management of local threats makes big difference ...

Worst Case (IPCC A1B) Best Case (IPCC B1)

Extent of ecosystems

relative to today (%)

Atm

osph

eric

CO

2 (pp

m)

Implications for the future?

Conclusion: Not too late but we need to take 4 urgent steps:

1. Stabilise of atmospheric CO2 well below 450 ppm (and +2oC)

2. Reduce the impact of local stresses on coastal ecosystems

3. Decrease vulnerability of coastal people and infrastructure

4. Establish financial mechanism to allow CT countries to respond to inevitable changes