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Climate change and the Reef

The real sea changeClimate change is one of thegreatest threats to coral reefsworldwide. More than 30 per centof coral reefs throughout theworld have already been affectedand scientists fear that 60 percent of reefs may lose manycorals by 2030 due to increasedcoral bleaching.

The Great Barrier Reef is one ofthe largest and healthiest reefsystems in the world and cancope with stress better than mostreefs, but it is not immune toclimate change.

Impacts on coral reefs – the ecosystemeffect Already, coral bleaching andother signs of coral stressare evident. But climatechange affects more thancorals. Seabirds, marinemammals, turtles, plankton,invertebrates, marine plants, fishand habitats such as wetlands andislands are also under threat.Because plants, animals andhabitats are integrally connected,the impacts of climate change willhave far reaching impacts on everypart of the coral reef ecosystem.

Climate changeimpacts on the Great Barrier Reef

Rising sea levelIncreased sea levels elevate the risk of coastal flooding from storm surges andintensify coastal erosion. Rising seawater can flood important bird and turtlenesting sites, wetland areas, mangroves and coastal towns.

Changing ocean circulationOcean currents transport oxygen, nutrients and an array of marine life. Theseocean conveyor belts connect reefs to each other and connect the coastline tothe Great Barrier Reef. Changes in ocean circulation impact food webs andinfluence the productivity of the ecosystem.

Altering rainfall, drought and run-off patternsRain patterns are changing. Some places are drier while others receive morerain. Intense rain leads to increased erosion and floodwaters that carrysediments, nutrients and pesticides to the Reef impacting on the plants andanimals that live there.

Ocean acidificationHigher levels of carbon dioxide in the atmosphere are absorbed by theoceans, affecting the chemistry of the ocean and making it more acidic. This reduces the growth rate and strength of corals and affects the limestonefoundations of the Reef.

Increasing frequency of intense stormsMore intense storms will magnify physical impacts on coastal areas,mangroves, seagrass beds, shallow reef habitats, islands and coral cays in theGreat Barrier Reef.

Increasing sea temperatureIncreases in sea temperature results in more frequent mass coral bleachingand a decrease in the overall growth of the Reef. Temperature increases willimpact other marine animals such as fish, turtles and seabirds.

If carbon dioxide levels continue to rise, the Great Barrier Reef could look verydifferent. It is up to us to determine what reefs of the future will be like.

Increase in temperature: + 1 degree

CO2 (ppm): 375

Increase in temperature: + 2 degrees

CO2 (ppm): 450-500

Increase in temperature:> +3 degrees

CO2 (ppm):> 500

ppm: parts per million

Degrees of change

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