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Rising Sea Levels Brought On By Climate Change Could Wipe Out The Great Barrier Reef 

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Climate change has drastically impacted our environment and its millions of inhabitants. In the 20th century, global sea levels specifically rose more rapidly than anytime within the past 3,000 years. By 2100, it’s projected to rise even further as climate change continues to escalate. 

The rapid melting of the Antarctic ice sheets is particularly becoming a problem, and reports show that sea levels can rise up to 5.2 feet from the melting. When sea levels rise, the multitude of ecosystems that exist throughout our oceans are negatively affected. 

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Scientists are looking at coral reefs in particular, as their ecosystems support the life of so many species. New research from Jody Webster, Juan Carlos Braga,  Marc Humblet, Stewart Fallon, and Yusuke Yokoyama, show that we can look at the history of coral reefs to better understand, and maybe even prevent, the future of Earth’s reefs. Their research was recently published in the publication Nature Communications. 

The team specifically looked at how the Great Barrier Reef in Australia reacted to a significant rise in sea levels around 13,000 to 10,000 years ago. Throughout history there has been a multitude of recorded “meltwater pulse events,” which refers to when ice sheets melt and dissipate in large quantities, causing global sea levels to rise. 

Sea levels rising can actually cause shallow-water reef systems to “drown,” due to the fact that corals and other organisms living in the reefs rely on the sun for photosynthesis. When the levels rise and the water becomes deeper, the organisms cannot properly perform photosynthesis to grow and thrive. 

An increased presence of sediment and rising temperatures brought on by climate change can also lead to drowning as it adds even more stress to the species within the reefs. 

The team said that by looking at cores from previously drowned fossil coral reefs can help give scientists an insight into what’s to come for the world’s reefs. Specifically fossil coral reefs that have been preserved on the continental shelf edge of the Great Barrier Reef. 

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These fossils reveal how past meltwater pulse events impacted reef growth, as well as how climate change specifically caused these melting events. 

“Although the Great Barrier Reef survived sea level rise roughly 11,000 years ago, the world was very different back then. Coral reefs faced less stress from human impacts. And ocean temperatures were rising more slowly,” the authors wrote for The Conversation. 

UNESCO’s World Heritage Committee has been reporting a high level of concern over the current state of the Great Barrier Reef and its future. Global warming, acidification of our Earth’s water, and pollution are also weakening our reefs. 

“Our findings suggest abrupt sea-level jumps of more than 11 meters are unlikely to occur without major instabilities in ice sheets. We’re in uncharted territory now, particularly with the Antarctic ice sheet displaying early signs of instability,” the authors wrote. 

“Our study also shows the Great Barrier Reef has been remarkably resilient, adapting to changing sea levels and continuing to grow even as the ocean rose rapidly. This resilience, however, had limits,” they wrote. 

The reef that they examined was found to have drowned about 10,000 years ago due to the multitude of stressors they cited throughout their observations. While there is hope from this evidence that shows reefs and their ecosystems can adapt to environmental changes, there will always be limits, especially as climate change intensifies. 

In order to protect our planet’s reefs, we need to use what the past has taught us. Reducing carbon emissions, protecting our oceans from pollution, and combatting environmental stressors brought on by humans is the key.

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80% Of The World’s Coral Reefs Have Been Impacted By Bleaching, Worst Global Event In History

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Earth’s coral reefs are officially in “uncharted territory,” according to scientists, after more than 80% of the reefs have undergone bleaching in what is being referred to as the worst global event on record.

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Great Barrier Reef

How Coral Bleaching In The Great Barrier Reef Has Impacted Its Inhabitants

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Climate Change has caused countless environments throughout the world to be destroyed, ecosystems to change, and species to face endangerment/extinction. The Great Barrier Reef in Australia has faced some of the greatest challenges throughout the past decade, and now, its enduring its third mass bleaching event within five years.

The last time the reef endured a mass bleaching event as intense as this one is gearing up to be, a third of all corals were killed, and fish populations declined rapidly, which also caused the specific ecosystems/species within the reef to change for the worse as well. A recent study wanted to analyze what actual effects these bleaching events have on the fish species that live among the coral reefs, as that could help us better prevent these types of things from occurring in other reefs around the world.

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The scientists behind the international study used something called “gene expression” as a tool to understand how well fish are able to handle hotter temperatures, which is an effect of coral bleaching. According to the study, gene expression is “the process where a gene is read by cell machinery and creates a product such as a protein, resulting in a physical trait.” Using this process, scientists were able to predict which fish species would specifically be the most at risk/affected by repeated heat waves that lead to bleaching. 

The study initially began in 2015 when the researchers collected liver biopsies from several species of coral reef fish after global ocean temperatures increased by 1 degree Celsius that year, however, at the time the team of scientists had no idea how different everything would look in just 5 years; in terms of coral bleaching, ocean temperatures/acidification, and climate change in general. 

It wasn’t until one year later that things took a turn for the worse. In 2016, Jodie Remmer, a lead author on the study, along with one other researcher on the project went to the Great Barrier Reef to work on a completely different project when they realized that the ocean temperature around them read as 33°C. This was absolutely shocking in the worst way possible, as 33°C was the same temperature that Remmer claims to have been used in a climate change simulation where scientists predicted what the world would look like, environment wise, by the year 2100, meaning climate change has intensified to a much more urgent level than anyone expected by 2016.

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After one week, Remmer claimed they watched entire patches of coral reef turn bone-white, as fish populations abandoned their homes in search of new resources for food. During that time, scientists collected genetic samples from a multitude of fish and coral species. What they were looking for is how these species “switched their genes on and off” based on environmental conditions. Some genes should always be on, and others should be regulated and used as a response to things like temperature stress (like during a bleaching event). 

The ability to turn these genes on and off is what gives all species the ability to maintain proper metabolic, respiratory, and immune responses to environmental changes. When this gene expression is compromised, so is the ability to survive, hence the massive decline in coral reef ecosystems/fish populations. 

“Our findings not only have implications for specific fish species, but for the whole ecosystem. So policymakers and the fishing industry should screen more species to predict which will be sensitive and which will tolerate warming waters and heatwaves. This is not a ‘one size fits all’ situation. Fish have been on the planet for more than 400 million years. Over time, they may adapt to rising temperatures or migrate to cooler waters. But, the three recent mass bleaching events are unprecedented in human history, and fish won’t have time to adapt,” Remmer stated. 

Remmer went on to say that her and her team’s goal has always been to protect the ocean and all of its inhabitants as much as possible. This new information and data isn’t very encouraging, however, it does give scientists and the government the sense of urgency they often need in order to justify a global response.