Friday, April 8, 2016

Climate Change and the Destruction of the Great Barrier Reef

The Great Barrier Reef is the largest coral reef ecosystem in the world, spanning 134,364 square miles (348,000 square kilometers for you metric-lovers), which makes it larger than the United Kingdom, Switzerland, and the Netherlands combined. You might think "oh that's just 3 small European countries so it's not THAT big" but you'd be thinking wrong, courtesy of helpful infographic below (courtesy of the Great Barrier Reef Marine Park Authority (GBRMPA)). 

The reef has a stunning amount of biodiversity as well: it contains 400 types of coral and hosts 1,500 types of fish and 4,000 mollusk species, as well many other species such as green sea turtles. Unsurprisingly, this massive biodiversity lead the Great Barrier Reef to be recognized as a World Heritage Area in 1981.

As an scuba diver, I've always wanted to visit the Great Barrier Reef, probably due to a healthy diet of Cousteau documentaries when I was younger. But now, I might not get to see a lively reef at all.

Why? Coral bleaching. This is what happens when corals are exposed to certain stresses, such as warmer-than-average waters (COUGH ANTHROPOGENIC CLIMATE CHANGE COUGH) for prolonged periods of time (we're not talking centuries though). In response to the stress, the corals expel the algae that give them their vibrant colors, meaning that the corals become white (due to their composition of limestone and other minerals, which don't have much color). This can be temporary, if the algae come back into the corals, but if the stress occurs for too long, the coral (which is made up of organisms, remember) can just die, and the algae can't recolonize them and restore the coral (and the color). In essence, on a large enough scale, this kills the reef.

Now, the Great Barrier Reef HAS experienced bleaching in the past. This is not some newfound phenomenon. Specifically, the reef had large bleaching events in 1998 and in 2002, but the current mass bleaching is vastly worse in the eyes of experts. Up to 95 percent of the GBR’s northern reefs are currently showing signs of extreme bleaching (in 2002, the bleaching there was only 18 percent).

Remember though, corals can survive bleaching! If the stress doesn't last long enough, the algae will recolonize the coral and the reef will be restored. Right now they don't have enough data to determine the long-term impacts of bleaching on the corals, but scientists are not optimistic: they estimate that 50% of the bleached corals will die, which is a huge amount given how much of the northern reefs are already bleached.

Alright, what's causing the bleaching, and can we fix it? As I hinted very subtly earlier, climate change is one of the big causes for the bleaching: ocean temperatures are rising in the area, and that's one of the biggest factors driving coral bleaching since corals are very sensitive to water temperature fluctuations (even a few degrees). In addition, El Niño, a famous weather pattern, is particularly strong this year, which further drives local water temperatures up, and the weather pattern is expected to continue throughout much of the year (increasing the duration of coral bleaching and thus increasing the mortality rate of the bleached corals). El Nino, along with other weather patterns (including but not limited to its Atlantic counterpart La Nina), are influenced by climate change in ways we don't fully understand (other than "this usually does not bode well for people and wildlife" but that's vague and not very scientific). As anthropogenic climate change continues to escalate, it's likely that coral bleaching (not just in the Great Barrier Reef, but in reefs all across the world) will continue to worsen, potentially making these beautiful natural phenomenon a thing of the past.

National Geographic does good reef coverage, check them out for great photos like these.

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