Coral reefs are home to over 25% of all marine life, but are threatened by many things - some natural and some man made. Water pollution, over fishing, careless recreation, collection of coral and human run-off are just a few of the man made threats - and climate change is increasingly thought to be a major concern.
Coral reefs are fragile ecosystems - they are thought to be the most sensitive ecosystem to long-term climate change as they can only tolerate a narrow temperature range. An increase in sea temperature could lead to the death of coral by bleaching - when ocean temperatures get too high, corals turn white, or 'bleach,' and eventually die.
According to many scientists sea temperatures will increase and the oceans of the world will become more acidic because of higher concentration of CO2. Both of these effects will damage corals and the ecosystems that they support.
Results from the Global Marine Species Assessment in 2008 show that the health of coral reefs differs significantly between geographic regions. The study shows that while only a quarter of Caribbean reefs are in good or excellent condition; nearly 70% of reefs in the Pacific are deemed as healthy.
Since the start of the industrial revolution, the acidic activity of the oceans has increased by 30 per cent. Many scientists believe that at current rates, they will become so acidic that few shell-forming organisms and coral reefs will be able to survive by mid-century. They believe the only real hope for corals in the long term, is a quick and sustained reduction in greenhouse gas emissions.