Approach: it’s a direct question. Introduce with gobal warming in brief and then detail in its impact on coral reefs especialy.
Human activities such as the burning of fossil fuels, deforestation and changing land use have dramatically altered the atmospheric concentration of greenhouse gases such as carbon dioxide and methane.
These changes have resulted in global warming and ocean acidification, both of which pose serious threats to coral reef ecosystems through increased thermal stress and ocean acidity as well as declining carbonate ion concentrations. Observed impacts on coral reefs include increased mass coral bleaching, declining calcification rates, and a range of other changes to subtle yet fundamentally important physiological and ecological processes.
There is little evidence that reef-building corals and other organisms will be able to adapt to these changes leading to the conclusion reef ecosystems will become rare globally by the middle of the current century.
Constraining the growth of carbon dioxide in the atmosphere as well as reducing local stresses such as overfishing and declining water quality, however, holds considerable hope for avoiding this gloomy future for coral reefs.
Given the importance of coral reefs to the livelihoods of millions of people, actions such as these must be pursued as a matter of extreme urgency.
Known as rain forests of the oceans, coral reefs are one of the most productive ecosystems on the earth. However, their survival is seriously threatened due to global warming.
How they are impacted:
Coral bleaching- corals are symbiotic associations between the host coral polyp and zooaxanthalle algae. When corals face stress due to rising temperatures, light, or nutrients, they expel the algae and turn white.
Large scale bleaching of the Great Barrier Reef of Australia in 2016 is an example of such phenomenon.
Andaman reefs are also reported to be undergone bleaching due to temperature rise.
Infectious diseases- rising sea temperatures also causes diseases among coral systems due to rise of bacteria such as viborio shiloi.
Solar irradiation- global warming results in changes in local weather patterns. With decreased cloud cover, the sunlight penetrates more into water increasing stress among corals.
Ocean Acidification- Due to increased CO2 levels in atmosphere, oceans absorb more CO2. This increases the acidity levels in water and inhibits the corals ability to build calcareous skeletons that are vital for their survival.
Rise of nutrients- Increased temperatures raise the activity of photosynthesis resulting in increased amounts of nutrients in water. This promotes population of organisms that compete with corals for growth.
Natural disasters- Global warming is associated with increases frequency of natural disasters. And this threatens the survival of corals.
Eg. 2004 tsunami resulted in massive loss of coral reefs.
With IPCC predicting a temperature rise of 2.5 c and UN reporting that 70 percent of world’s corals are threatened, its high time we must take steps to protect this vital and sensitive ecosystem.