How Has Climate Change Affected the Great Barrier Reef?

Time appears to be running out for the treasured corals of the Great Barrier Reef. A 2016 survey of 84 reefs by scientists in Australia found evidence of widespread bleaching at a whopping 93 percent of reefs. They said that 35 percent of corals have already died in the northern and central sectors of the famous reef.

Bleaching is different from actual coral death, and there still may be time for recovery. Bleaching occurs when nutrient-rich algae leaves the coral, causing the colorful animals to turn white. If environmental conditions improve, the coral can come back, but the effects of climate change, which cause abnormally warm ocean water temperatures, are not expected to abate.

A coral reef under siege:

• Bleaching occurs when corals under stress drive out the algae, known as zooxanthellae.
• If normal conditions return to the Great Barrier Reef, the compromised corals can recover -- but it can be a long process that can take decades.
• The southern sector of the reef has been mostly spared, thanks to ocean churning and rainfall in the wake of Tropical Cyclone Winston, which cooled waters in the area in February 2016.

Frequently Asked Questions

What impact does climate change have on the Great Barrier Reef?

Climate change has led to increased sea temperatures, which cause coral bleaching—a stress response where corals expel the symbiotic algae living in their tissues, losing their color and vital energy source. This can lead to widespread coral death if conditions persist. Additionally, ocean acidification, a result of increased CO2 absorption, weakens coral skeletons, making them more susceptible to damage.

How does coral bleaching affect the Great Barrier Reef's ecosystem?

Coral bleaching disrupts the delicate balance of the reef's ecosystem. As corals die, the biodiversity of the reef declines, affecting species that depend on the coral for food and habitat. According to the Australian Marine Conservation Society, severe bleaching events in 2016 and 2017 impacted over half of the Great Barrier Reef, leading to a significant loss of coral cover.

Are there any signs of recovery for the Great Barrier Reef?

Some parts of the Great Barrier Reef have shown signs of recovery in areas less affected by bleaching, where water conditions remain favorable. However, recovery is slow and can take decades. The resilience of the reef is also threatened by repeated bleaching events, which do not allow sufficient time for full recovery, as reported by the Great Barrier Reef Marine Park Authority.

What other factors related to climate change threaten the Great Barrier Reef?

Beyond bleaching, climate change exacerbates the frequency and intensity of extreme weather events, such as cyclones, which can cause physical damage to the reef structure. Rising sea levels and changing ocean currents also alter the distribution of marine species and can impact the availability of nutrients and sunlight needed for coral health.

How does the decline of the Great Barrier Reef affect human communities?

The decline of the Great Barrier Reef has significant implications for human communities, particularly in Australia. The reef supports a vibrant tourism industry and provides livelihoods for thousands of people. It also acts as a natural barrier protecting coastal communities from storm surges. The loss of the reef could lead to economic downturns and increased vulnerability to natural disasters.

What actions are being taken to mitigate climate change impacts on the Great Barrier Reef?

Efforts to mitigate climate change impacts on the Great Barrier Reef include reducing greenhouse gas emissions, improving water quality through reduced agricultural runoff, and implementing conservation programs. The Australian government has also invested in the Reef 2050 Plan, which aims to enhance the resilience of the reef through various restoration and adaptation strategies.