WHATEVER KIND OF diver you are, you’ll know that your next great dive depends on healthy coral reefs. Coral reefs are the world’s bustling underwater cities. Home to at least one quarter of all marine life in the ocean they generate USD 300–400 billion each year from tourism, fisheries and coastal protection. If you’re a seasoned diver you’ll also know that coral reefs are dying faster than ever before. In the last 30 years we’ve lost half of our corals globally and, in 2016, a single bleaching event killed off 20 percent of coral on the Great Barrier Reef.

Divers have been witnessing mass bleaching events for decades across reefs in the Atlantic, the Pacific and the Indian Oceans. These events have become more frequent and more devastating in recent years as greenhouse gas emissions continue to rise. Scientists predict that the resulting sea temperature rise will soon cause severe annual bleaching events. It takes at least five years, but usually much longer, for a reef to recover from a single bleaching event. Frequent and severe bleaching will inevitably cause major changes to the reef environment we know and love. Unless we take action now, we could lose most of our reefs to the impacts of climate change by 2050.

THE WINNERS AND LOSERS OF GLOBAL CLIMATE CHANGE
But where do you start when the world is covered with over 294,000 square kilometres of coral reef? Cutting-edge research from UN Environment has recently determined that some reefs will not start experiencing severe annual bleaching events until years, or even several decades, after others. These are the winners of global climate change and are known by scientists as “climate refugia”. To predict the time when corals are most likely to be affected, scientists use Degree Heating Weeks. This is a measure of the intensity and duration of a warming sea. Widespread bleaching and coral mortality is expected to occur when the scale reaches 8 Degree Heating Weeks. This represents eight weeks of ocean warming that is at least one degree Celsius above the seasonal average.

A diver dwarfed by the sardines at Pescador Island in the Philippines (Photo by The Reef-World Foundation)

Many popular diving destinations across Southeast Asia have already been divided up into climate winners and losers based on the world’s current greenhouse gas emissions. Picture the central Philippines, for example; Moalboal is famous for submerging curious divers in enormous schools of sardines around Pescador Island. Under current climate projections, Moalboal will experience mass bleaching events, at least 10 times a decade from 2033. Just under 200 kilometres north however, the thresher shark diving hotspot of Malapascua, isn’t expected to experience this until 2050.

BATTLE THE BLEACHING
In 2016, the hottest year on record for the third year in a row, the global community listened to science and decided to invest in the future. One hundred and ninety-six nations signed the Paris Agreement and pledged to pursue concrete efforts to keep the warming of the Earth’s temperature well below two degrees Celsius. Already at +0.99 degrees Celsius, however, if current trends continue and the world fails to reduce greenhouse gas emissions, then severe bleaching will occur every year on 99 percent of the world’s reefs within the century.

By following best practices, divers can ensure that their dives have minimal negative impact on delicate reef ecosystems (Photo by The Reef-World Foundation)

Finally, diplomats, scientists and politicians have agreed to fight global climate change. But the charge doesn’t rest solely on their shoulders. We can all do our part to protect the Earth and its precious coral reefs from rising sea temperatures and coral bleaching.

WHAT CAN DIVERS DO?
Divers have a powerful connection with the ocean and are in one of the strongest positions to combat bleaching. They are in the water every day, noticing even the subtlest of changes to a reef. The Green Fins initiative recognises that unique connection and gives divers clear ways they can channel their strength for maximum effect. Dive and snorkel centres that sign up for Green Fins membership pledge to align their business practices to a set of environmentally friendly standards, known as the Green Fins Code of Conduct. These standards range from ensuring divers do not touch or harass marine life, to responsibly disposing of used oil. Centres strive to do everything within their power to remove the added stress of marine tourism so that corals remain strong enough to fend off bleaching.

A project now underway in the Philippines aims to focus Green Fins expansion to reefs that have been identified as climate refugia, the winners of global climate change. By prioritising conservation and management efforts on these reefs, efforts are focused on areas that may still have time to adapt to our warming seas. By adopting the Green Fins ethos, the diving community can take real action to fight coral bleaching. Dive operators can use the climate change projections to understand their vulnerability to the impacts of climate change and, where necessary, plan other actions that will reduce their vulnerability, for example, explore business strategies that use, as well as ensure protection of, climate refugia.

Read the rest of this article in 2017 Issue 1 Volume 144 of Asian Diver magazine by subscribing here or check out all of our publications here.

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