Global average temperature has risen approximately 1°C since the industrial revolution when humans started burning fossil fuels. While 1°C of warming may not seem like a lot, there have already been serious consequences for human and natural systems around the world.
What do climate scientists tell us is happening across the Caribbean? We are seeing an increase in the number of very hot days, frequent and extended droughts, intense rainfall events leading to flooding, and rising sea levels that are eating away at the beaches on which tourism in the region depends. Perhaps the most alarming and talked about threat from climate change is the expectation that we will experience more frequent, intense storms.
Last year’s hurricane season was harrowing for the Caribbean, with two Category 5 storms battering the region. The devastation was catastrophic; in Dominica it’s estimated that nearly every home was damaged or destroyed, while in Barbuda, close to 100 per cent of the population was displaced.
Just 1°C of warming has already changed the reality of life in the Caribbean and it’s not just the climate that is changing. Our ecosystems are being drastically altered as well, resulting in serious threats to biodiversity and the ecosystem services provided by our marine environment.
In this brief article I want to share how climate change is impacting coral reefs, the threat this poses for a small island like Barbados and how we are responding to this challenge.
Corals are tiny animals that survive due to a partnership with microscopic algae, called zooxanthellae which live inside the coral’s tissue and give corals their beautiful colours. The relationship is mutually beneficial; the coral provides protection for the algae and the algae makes most of the food for the coral animal through photosynthesis. This partnership allows the corals to build the hard limestone skeleton which provides the three dimensional structure to the reef. These structures in turn become home to a diverse array of species; which are a source of food and jobs for millions of people globally. Critically, coral reefs also diminish the energy of waves, protecting coastlines from erosion and damage.
Healthy corals can survive only within a narrow temperature range. Water temperatures of even 1-2°C above what corals normally experience cause a stress response in which corals expel their zooxanthellae, leaving behind the transparent coral animals and their white skeletons. This stress response is called “coral bleaching”. Bleached corals are still alive, but their growth and reproduction soon become compromised. If water temperatures remain elevated for weeks, the coral animals may starve or become diseased and eventually die, leaving behind only their skeleton. Through erosion, the structural integrity of the reef is soon lost, along with its ability to act as a home for reef-dwelling organisms and provide coastal protection.
The problem is that before this era of human-induced climate warming, bleaching events were relatively rare, which allowed time for full recovery of the reef between events. However, as the climate changes, we are seeing more and more bleaching events, leaving coral reefs with not enough time to recover.
Earlier this month, the Intergovernmental Panel on Climate Change (IPCC) released a special report on the impacts of further global warming of 0.5°C. The report found that “Global warming is likely to reach 1.5°C between 2030 and 2052 if it continues to increase at the current rate”.
What’s the likely fate of coral reefs? According to the report, coral reefs are projected to decline by a further 70–90 per cent at 1.5°C and will be almost completely lost (>99 per cent) at an increase of 2°C. Such projections are particularly grim in light of the fact that Caribbean reefs have already been severely degraded over the last few decades from a combination of coastal development, over fishing, disease outbreaks and past bleaching events. Moreover, two of the formerly most abundant species, the staghorn and elkhorn corals, have been added to the US Endangered Species List. Climate change is another major stressor facing an already stressed system.
In Barbados, the loss of coral reefs means the loss of jobs, food and income for the entire country. Tourism is our most important economic activity and source of employment and the vast majority of it occurs along the coast, on beaches and near coral reefs. Indeed, much of the island’s infrastructure is concentrated along the coast which will face a higher risk of flooding and erosion. Reef-based fisheries are particularly important outside of the regular fishing season and are becoming less productive. The well-being of coastal communities, whose history and identity are connected to the sea, is also seriously at risk. While the Caribbean and other small island developing states have urged that global warming be kept to 1.5°C, even under this scenario, the challenges we face will be unprecedented.
In the long-term, the best option for coral reefs is to reduce greenhouse gas emissions and slow global warming. However, as a small island, Barbados’ contribution to global greenhouse gas emissions is relatively insignificant. What we need is to build the resilience of our reefs; to strengthen their ability to resist and recover from threats we cannot control such as rising sea temperatures
This comes down to properly managing local stressors on our reefs such as coastal development, runoff from land-based pollution and over fishing.
On an individual level there is much that can be done to lessen your impact such as wearing reef safe sunscreen, not sending excess chemical waste into our waterways and choosing not to eat parrotfish (chubs), a key herbivorous fish that helps to keep reefs healthy.
At the national level there is now discussion about expanding marine protected areas, banning single-use plastics and the potential for coral restoration to help revive degraded reef areas. Much effort is also being spent by local organizations to communicate to the public why coral reefs matter, and what people can do to change the current trajectory. At this point, we need to explore every option and get everyone onboard to tackle the single greatest threat of our generation.
Nikki Hassell is an environmental professional based at Bellairs Research Institute and a member of the Coral Reef Restoration Alliance.