What Is The Role Of Coral Reefs In Climate Change?

by Olivia Draycott

Coral Reefs: Why Are They Crucial For The Climate?

Coral Reefs, at first glance, may appear to be a form of marine vegetation, yet this is not the case. Coral reefs are in fact made up of polyps, animals that take in carbon dioxide (CO₂) and release oxygen (O₂)  during their feeding process [1]. These polyps, despite homing over a quarter of the globe’s marine life, only constitute 0.1% of the ocean floor , and are facing the brutal threat of climate change[1]. Polyps are extremely sensitive to changing temperatures and rising levels of anthropogenic  greenhouse gases (those proudced by humans), including  CO₂ and Methane (CH₄), which result in coral bleaching [2].

Coral bleaching is the largest threat to polyps, as an increase of 1–2°C in ocean temperatures over a sustained period can result in bleaching. During this process,corals turn white and, in the most drastic cases, die [3]. This is an issue as coral reefs are estimated to support over 500 million people worldwide, who rely on them for daily subsistence. The food and livelihoods provided are  worth around £300 billion each year, and those who rely on them often come from lower-income countries [3; 4]. Additionally, the reefs protect coastlines against extreme weather conditions by reducing the impact of land erosion in coastal areas. The ridged structure of the corals acts as a natural barrier that reduces the energy within waves by up to 97%, thus lowering the impact of Tsunamis and hurricanes globally [4]. Consequently, the impact that the reefs have when reducing the impacts of climate change is immense.

Why Should We Be Concerned With The Protection Of Coral Reefs?

As stated, coral reefs house over a quarter of all sea life on earth, provide vital protection for coastal communities, and act as natural carbon sinks. In addition to the critical role coral reefs have in this area of society, they are also crucial in medical developments. Developments in the medical field occur as extracts from the inhabitants living in, and on, the reefs have been used to develop treatments for asthma, arthritis, cancer and heart disease [5]. Without true protection and a reduction in global temperatures, this may not be possible in the future. 

Coral reefs are also a key indicator of climate change, and are often used to detect threats to more resilient ecosystems, due to their sensitivity to change [2]. If large scale deterioration of coral reefs occurs, the deterioration of other systems may cascade at an unprecedented rate. This was demonstrated in the catastrophic loss during the bleaching of the Great Barrier Reef in 2016 and 2017, where 50% of the corals inhabiting the reef were killed [3]. This impacted ecosystems profoundly, as the mass death of coral is not an issue which occurs in isolation. With global temperatures surpassing the desired 1.5? maximum, coral bleaching is more likely than ever to cause irreversible harm, such as large shifts in fish communities, and reduced catches for fishers targeting reef fish species in lower-income countries [6].

References:

[1] WWF (2022), Coral reefs and climate change: from cradle to an early grave. Available at: https://www.wwf.org.uk/coral-reefs-and-climate-change  (Accessed: 18 February 2022).
[2] SeCore International (2022), How climate change affects corals. Available at: http://www.secore.org/site/our-work/detail/how-climate-change-affects-corals.55.html  (Accessed: 18 February 2022).
[3] IUCN (2017), Coral reefs and climate change. . Available at: https://www.iucn.org/resources/issues-briefs/coral-reefs-and-climate-change  (Accessed: 18 February 2022).
[4] National Oceanic and Atmospheric Administration (2022), Coral Reef Ecosystems  . Available at: https://www.noaa.gov/education/resource-collections/marine-life/coral-reef-ecosystems#:~:text=Coral%20reefs%20protect%20coastlines%20from,food%2C%20income%2C%20and%20protection  (Accessed: 18 February 2022). 
[5] Natural History Museum (2022), Why are coral reefs important?,  Available at: https://www.nhm.ac.uk/discover/quick-questions/why-are-coral-reefs-important.html  (Accessed: 18 February 2022).
[6] Reef Resilience (2022), Bleaching Impacts,  . Available at: https://reefresilience.org/stressors/bleaching/bleaching-impacts/  (Accessed: 18 February 2022).