Coral Collapse: Reef Ecosystems May Erode by 94% In Next Three Decades If Climate Change Continues
Coral reef ecosystem
(NOAA)Coral reefs are one of the most valuable ecosystems on Earth. Nestling in the deep waters of our planet, these underwater ecosystems are often referred to as the ‘rainforests of the sea’, as they host a plethora of animals and plant species with diverse sizes and peculiar appearances.
But in recent years, coral reefs have been facing the brunt of global warming, which has exposed them to a plethora of problems. Several scientific studies have already pointed towards the vast spread of threats associated with the rising greenhouse gas emissions that these delicate systems are facing.
Adding to that, another new study has highlighted the implications of global warming on coral reefs, ringing the alarms that we are running out of time to save this environmental trove.
“The threat posed by climate change to coral reefs is already very apparent based on recurrent episodes of mass coral bleaching. But changing environmental conditions will have other far-reaching consequences,” said Prof Morgan Pratchett, co-author of the study.
Calcification of corals
Coral bleaching of inshore reefs in Solomon Islands
(IANS)For this study, the team estimated the impact of the two greatest threats to the underwater ecosystems: ocean warming and acidification. The data was obtained from 183 distinct reefs located in 233 locations of the globe.
Following this, the team calculated the growth trend with respect to the threats faced by the reefs across the world. As per the authors, this is the first quantitative study to estimate the growth of coral reefs with respect to climate change.
The team focused specifically on the most important phenomenon linked with the growth of reefs: calcification. This refers to the formation of thin layers of calcium carbonate among the reef that gives the overall unique skeleton structure to the ecosystem. But now, the production of this calcium carbonate skeleton is being threatened due to ocean warming and acidification.
In terms of geographic location, the team noted the highest production decline in the Atlantic Ocean by 49%, followed by the Indian Ocean (39%) and Pacific Ocean (11%).
Out of all, the researchers predict that coral mass bleaching events are most likely to have the greatest impact on carbonate production worldwide. Bleaching occurs when corals are overburdened or stressed by the change in surrounding conditions—like increasing temperatures, ocean acidification, changes in light or nutrients. They break this symbiotic relationship with algae, thus causing them to turn white, or ‘bleach’.
Decline in growth rate
Rapture Reef sits within the Northwestern Hawaiian Islands Marine National Monument. The monument encompasses more than 140,000 square miles of ocean and coral reef habitat.
(NOAA)This is a first-of-its-kind study that brings to light the growth dynamics of coral reefs and how it can result in stunting if the warming goes unabated. The authors have warned that the repercussions of oceanic warming can severely impact the growing ability of the reefs across the globe. And this may happen anytime soon, unless we are able to somehow restrict the carbon emissions and secure the future of coral reefs.
The calculations project that by 2050, the global coral reefs population may erode drastically by 94%. On the other hand, even in other scenarios, the study estimates that the coral reefs will no longer be able to grow vertically by 2100.
"While 63% of reefs are projected to continue to accrete (grow) by 2100 under the low-impact pathway, 94% will be eroding by 2050 under the worst-case scenario. And no reef will continue to accrete at rates matching projected sea-level rise under the medium and high-impact scenarios by 2100," explains Dr Christopher Cornwall, lead author of the study.
The team measured the growth rate with computer models based on the emission scenarios of the Intergovernmental Panel on Climate Change. These scenarios include low, medium, and high impact with respect to outcomes on ocean warming and acidification for 2050 and 2100.
Such a rapid decline in the coral ecosystem can have an adverse impact on all the other aquatic populations thriving in its abode—mainly the fish species. As per NOAA, nearly 25% of the ocean’s fish depend on coral reefs, which makes these systems’ health really important.
On the other hand, its decline may also impact the lives of millions of people who depend on this ecosystem for their livelihoods. Therefore, there is an urgent need to curb carbon dioxide emission, in order to help coral reefs thrive in the near future.
The study has been published in the journal PNAS and can be accessed here.
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