What Contribution Do Oceans Make to Climate Change?

The oceans are the largest absorbers of carbon dioxide emissions, taking in approximately 25% of human-generated carbon each year. Additionally, rising ocean temperatures are altering global weather patterns, and melting ice caps are accelerating sea-level rise.

Marine ecosystems are crucial for sustaining the "Blue Economy," benefiting biodiversity, providing protein sources, and supporting millions of livelihoods worldwide. The fishing sector alone employs around 35 million individuals globally, according to the International Labour Organization (ILO).

Coral reefs, known for their biodiversity, host about 25% of fish species during various life stages. The loss of these vibrant habitats can trigger extensive ecosystem disruptions, leading to broader declines in marine life. Furthermore, coral reefs are significant for tourism, generating between $30 billion to over $375 billion in annual economic activity.

Blue Ecosystems as Shields Against Extreme Weather

In addition to their economic value, underwater ecosystems serve as natural storm barriers. With the increasing severity and frequency of storms attributed to climate change, these marine habitats face significant threats.

The degradation of coral, mangroves, and fisheries diminishes their capacity to protect coastal communities, economies, and assets, particularly in developing regions.

How Do Coral Reefs Safeguard Lives and Properties?

After Hurricane Irma, coral researcher Erich Bartels from the Mote Marine Laboratory noted that the destruction would have been far more catastrophic without the protective presence of coral reefs. Without these natural barriers, waves exceeding 6 meters would have directly struck the Florida Keys, causing even greater devastation.

> “We lost a lot of our live coral out there. The coral gave its life so our buildings are still here.” > > — Erich Bartels, scientist at Mote Marine Laboratory.

Coral reefs absorb wave energy and lessen storm surges, forming essential buffers for coastal cities against loss of life, property damage, and erosion. Though they cover less than 1% of the ocean floor, these complex structures are critical during storms, as they dissipate the energy of incoming waves.

Millions of people in the United States reside near coral reefs, benefiting from their protective capabilities.

The Threats Facing Coral Reefs

Globally, coral reefs are suffering due to human actions, particularly climate change, with around 50% lost in the last three decades. The oceans have absorbed about 90% of the excess heat from global warming, leading to increased acidification from carbon dioxide uptake.

When corals experience stress from changing temperatures, light, or nutrient levels, they expel the symbiotic algae residing in their tissues, resulting in bleaching. This process not only diminishes coral color but also their ability to produce food, making them more susceptible to starvation, diseases, and mortality.

Since 2016, bleaching events have decimated half of the Great Barrier Reef, the world's largest reef system. If conditions do not improve, projections indicate that by 2030, 98% of coral reefs could face lethal environments.

The Human Impact on Coral Reefs

In addition to climate stressors, overfishing disrupts food chains, leading to an increase in algae and parasites that harm coral. Development activities like docks and bridges often encroach on these fragile ecosystems. Boating activities further exacerbate the damage by dragging anchors and nets along the seafloor, while urban runoff and agricultural pollution indirectly stress these habitats.

The Decline of Coral Reefs Means Diminished Protection for Communities

> “Unfortunately, we are already losing the height and complexity of shallow reefs around the world, so we are likely already seeing increases in flood damages along many tropical coastlines.” > > — Michael Beck, lead marine scientist at The Nature Conservancy.

Research underscores the economic implications of preserving coral reefs, as they provide substantial flood protection. A study by the Nature Conservancy indicates that without coral reefs, floods would impact approximately 70% more land and affect 81% more people annually.

The frequency and severity of storms are projected to worsen, with significant increases in flood damages expected from so-called "100-year storms," which now occur more frequently. Combined with rising sea levels, the costs of flood damage could quadruple.

Another study published in Nature Communications utilized catastrophe risk models to estimate the property damage prevented by coral reefs, concluding that without them, annual flood damages could double from $4 billion to $8 billion. Countries like Indonesia, the Philippines, and Mexico could each face over $400 million in additional flood damages each year, while the United States could incur about $94 million more.

Restoration Efforts for Coral Reefs

The Great Barrier Reef, a UNESCO World Heritage Site spanning 2,300 km, has lost half of its coral in recent years due to two major bleaching incidents in 2016 and 2017, a trend evident in coral reefs globally.

Efforts to restore coral and rehabilitate bleached reefs involve identifying heat- and acid-resistant coral species and developing rapid regrowth techniques to replenish dying reefs. Researchers funded by the Great Barrier Reef Foundation have achieved remarkable results, accelerating the growth of coral organisms that would typically take a century or more to develop.

Peter Harrison, a pioneer in coral spawning research, is leading initiatives to expedite coral regrowth on the Great Barrier Reef, including a coral fertility treatment to replant larvae after harvesting eggs and sperm.

Experts believe that, with sufficient support, coral reefs can recover in many areas, but the pressing question remains: how can we finance this global restoration effort? The urgency of action is clear; inaction is no longer an option.

The global political and financial systems must back immediate reductions in carbon emissions, as the escalating pressure on natural systems will have profound consequences. Future discussions will delve into innovations in Blue Finance aimed at addressing these challenges.