What Australia’s Floods Mean for the Great Barrier Reef

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As New York shovels out of the snow and LA digs out of the mud, Australians are facing their own onslaught of extreme weather. The worst floods in half a century have hit the central and southern parts of Queensland, forcing at least 1000 residents to evacuate their homes with warnings that the worst may be yet to come as rivers in the region continue to swell.

I visited Queensland in July, just north of where the flash floods have hit. After years of crippling drought, the landscape was laced with bone-dry creek beds, and the withered vegetation looked like it could spontaneously combust at any moment. But I met several farmers and cattle ranchers (or graziers as they’re called Down Under) who assured me this was a seasonal state of affairs. When it rains in Queensland, they said, it pours. How right they were: On Tuesday, several towns in the region were underwater, and hundreds of millions of dollars in damage has already been done to local crops.

The farther-reaching consequences of those floods is harder to gauge. I was in Queensland to work on a story about the Great Barrier Reef, one of the world’s largest and most delicate ecosystems. The reef is hugely affected by runoff from the many rivers that empty into the waters off Australia’s east coast — rivers that run through thousands of acres of ranch and cropland.

(Watch a video about Pakistan’s floods.)

For years, scientists studying the GBR’s corals have collected information on how the runoff damages the tiny animals that build the reefs Australia is so proud of. The sediment washed downstream during floods like these, which can carry fertilizer nutrients, insecticides and herbicides, can throw the Reef’s ecosystem out of whack in a variety of ways, from literally smothering the reef under a blanket of dirt to causing phytoplankton growth and algae blooms that compete with the corals. In extreme cases, these conditions can cause reefs’ collapse.

The monsoon that occurs during Australia’s summer is an annual event, and there is a whole lot that anyone can do about the extreme weather Queensland endures. To try to mitigate the problem, the government has been calling on sugar cane farmers and graziers with increasing urgency to change the way they manage their land to minimize impact on the valuable offshore landmark. In the past, many Queensland farmers packed too many cattle onto the land, already ill-suited to non-native hard-hoofed herd animals, leading to overgrazing and, in turn, too much loose topsoil that ran into rivers and into the ocean.

Now graziers are being asked to reduce and report the number of cattle that run on their property, and sugar cane farmers, also abundant in the state, are being asked to limit and report back on the amount of fertilizer and chemicals they use. It’s a level of public involvement that makes some farmers and graziers feel unfairly targeted, when there are plenty of others more directly involved with the reef. “We’re not out to rape and pillage the land,” says Kevin Mann, who has been running a sugar cane plantation on Australia’s east coast since 1980. “If we did, we’d have no farm left.”

It remains to be seen how — or if — this season’s flooding will affect the Great Barrier Reef, but last year, sediment plumes extended for 25 kilometers in some areas. You can see a few photos here.