Climate Change: A death note for coral reefs?
Be it the Great Barrier Reef, the New Caledonian Reef, the Red Sea Coral Reef, or reefs in the waters of the Great Chagos Archipelagos – coral reefs are intricate and majestic living marine architectures which form the vibrant cities of our oceans. They cover a mere 0.1% of the sea, yet they are home to around 25% of the marine biodiversity1. It is therefore unsurprising that life across coral reefs can get as busy as cities like London or New York. Akin to such metropolises, the disappearance of coral reefs seems very unlikely; yet, we are losing them at an alarming rate. While their loss can be attributed to several factors including pollution and destructive fishing practices, coral bleaching due to climate change is the biggest threat today –
Coral bleaching has already claimed around 50% of the world’s coral reefs leading to the endangerment of several dependent marine species. This destruction directly impacts humans in multiple ways – from our fishery industries to our ability to discover new drugs against diseases as deadly as cancer. So, what is coral bleaching? As the name suggests, it literally means the corals losing their vivid
In the event of a stressful situation – especially the rise in the seawater temperature, this mutualistic relationship is disrupted, and corals bleach by expelling their
El Niño is a natural phenomenon and involves the occurrence of unusually warm water in the Pacific Ocean7, while the unprecedented rate at which our climate is changing and the consequential temperature rise are human-driven. Let’s briefly review the science. Climate change is the outcome of an upward shift in the Earth’s atmospheric greenhouse gases caused by agriculture and the burning of fossil fuels, among others. The greenhouse gases (which are mainly carbon dioxide, methane and water
For decades, the oceans have profusely absorbed excess heat generated by the surplus of greenhouse gases in our atmosphere, thereby warming the oceans. As the years pass by, it is apparent that thermal stress in the marine environment is being amplified at an exponential rate as depicted by the above-mentioned recent back-to-back mass coral bleaching events. From 2014 to 2017, it has been reported that 70% of the world’s coral reefs have been affected while in over two decades, we have lost over 50% of the world’s coral reefs due to mainly global climate change worsened by other factors including El Niño8. At this rate, the collapse of an entire ecosystem is imminent. In fact, scientists predict that by 2050, 90% of the coral reefs around the globe will be wiped out. Some even dare to say that the future seas will be slimy, teeming with jellyfish9. Why should we care? If this scenario becomes a reality, the marine ecological collapse will have a ripple effect on our
There is still a reason to be optimistic though. The 10% of coral reefs that will survive will be pretty resilient. In fact, such occurrences have already been reported. On the Great Barrier Reef in Australia, scientists have observed that between the last two consecutive bleaching events, which occurred in 2016 and 2017, coral reefs took longer to bleach in 2017 even when subjected to higher temperatures10. Interestingly, others have reported that in other parts of the world adaptive mechanisms and, probably even more importantly, natural selection for heat-tolerant corals have been observed. While scientists may disagree on many aspects concerning the future of coral reefs in a steadily warming ocean, almost all of them firmly believe that for corals to survive in the twenty-first century, they need time to adapt to the changing environment. Indeed, the evolution of such an organism cannot happen overnight. Therefore, the problem which they face today can be described as a race between how fast they can adapt and that of the changing climate11.
Today, time seems to be a luxury which coral reefs do not have to allow their evolution into climate change resilient species. Yet, time is the prime prerequisite to prevent a global marine ecological collapse. There is still hope for the world’s coral reefs, as long as we slow down climate change.
This article was specialist edited by Kym Bain and copy-edited by Dzachary Zainudden.
- For more information check out this website: https://www.scientificamerican.com/article/scientists-are-taking-extreme-steps-to-help-corals-survive/
- For more information check out this website: https://oceanservice.noaa.gov/facts/coral.html