the impact of global warming on coral life system

Destruction of coral reef can be induced by a variety of factors, alone or in combination. However, unprecedented global warming and climate change combined with growing local pressures have resulted in destruction of coral reefs to a large extent. 

Impact of global warming on the coral life system: 

Coral Bleaching 

• The impacts from coral bleaching are becoming global in scale, and are increasing in frequency and intensity. 

• Mass coral bleaching generally happen, when temperatures around coral reefs exceed 1 degree Celsius above an area’s historical norm for four or more weeks. Sea surface temperature increases have been strongly associated with El Nino weather patterns.

• However, light intensity, (during doldrums, i.e. flat calm conditions), also plays a critical role in triggering the bleaching response. If temperatures climb to more than 20 C for similar or longer periods, coral moralities following bleaching increase. 

Rising sea levels 

• Observations since 1961 show that the average temperature of the global ocean has increased even at depths of 3000m (IPCC report), and that the ocean has been absorbing more than 80% of the heat added to the climate system. Such warming causes sea level rise and creates problems for low-lying nations and islands. 

Ocean acidification 

• It refers to a change in ocean chemistry in response to the uptake of carbon dioxide from the atmosphere. The amount of carbon dioxide in the atmosphere is in equilibrium with that in seawater, so when atmospheric concentrations increase, so do oceanic concentrations. 

• Carbon dioxide entering seawater reacts to form carbonic acid, causing an increase in acidity. 

• Each year, the ocean absorbs about one-quarter of the carbon dioxide emitted from the burning of fossil fuels (oil, coal, and natural gas). 

• Since the Industrial Revolution, ocean acidity has increased by about 30%, a rate that is more than 10 times what has previously occurred for millions of years. Further, ocean acidity levels are expected to increase by an additional 40% above present levels by the end of this century. 

Coral reefs harbor the highest biodiversity of any ecosystem globally and directly support over 500 million people worldwide, mostly in poor countries. According to UNESCO, the coral reefs in all 29 reef-containing World Heritage sites would cease to exist by the end of this century, if we continue to emit greenhouse gases. Limiting global average temperature to well below 2°C above pre-industrial levels in line with the Paris Agreement provides the only chance for the survival of coral reefs globally