Global warming’s extreme rains threaten Hawaii’s coral reefs

  • In this 2020 aerial photo provided by the Arizona State University’s Global Airborne Observatory, runoff from the island of Molokai in Hawaii flows into the ocean. Recent flooding in Hawaii caused widespread and obvious damage. But extreme regional rain events that are predicted to become more common with global warming do not only wreak havoc on land, the runoff from these increasingly severe storms is also threatening Hawaii’s coral reefs. (Global Airborne Observatory, Arizona State University via AP)

  • In this 2020 aerial photo provided by the Arizona State University’s Global Airborne Observatory, runoff from the island of Molokai in Hawaii flows into the ocean. Recent flooding in Hawaii caused widespread and obvious damage. But extreme regional rain events that are predicted to become more common with global warming do not only wreak havoc on land, the runoff from these increasingly severe storms is also threatening Hawaii’s coral reefs. (Global Airborne Observatory, Arizona State University via AP)

  • FILE - In this Sept. 12, 2019, file photo, sea urchins and fish are seen on a coral reef in Kahala’u Bay in Kailua-Kona, Hawaii. Flooding in March 2021 in Hawaii caused widespread and obvious damage. But extreme regional rain events that are predicted to become more common with global warming do not only wreak havoc on land, the runoff from these increasingly severe storms is also threatening Hawaii’s coral reefs. (AP Photo/Caleb Jones, File)

  • In this March 9, 2021, photo, a house in Haleiwa, Hawaii, is surrounded by flood water after heavy rains. Recent flooding in Hawaii caused widespread and obvious damage. But extreme regional rain events that are predicted to become more common with global warming do not only wreak havoc on land, the runoff from these increasingly severe storms is also threatening Hawaii’s coral reefs. (Jamm Aquino/Honolulu Star-Advertiser via AP)

  • In this Nov. 23, 2003, photo provided by Ku’ulei Rodgers, muddy floodwater flows over a nearshore coral reef off the Hawaiian Island of Lanai after a heavy rainstorm. Flooding in March 2021, in Hawaii caused widespread and obvious damage. But extreme regional rain events that are predicted to become more common with global warming do not only wreak havoc on land, the runoff from these increasingly severe storms is also threatening Hawaii’s coral reefs. (Ku’ulei Rodgers/University of Hawaii via AP)

  • In this 2020 satellite image provided by the Arizona State University’s Center for Global Discovery and Conservation Science, Allen Coral Atlas, runoff from the island of Molokai in Hawaii flows into the ocean. Recent flooding in Hawaii caused widespread and obvious damage. But extreme regional rain events that are predicted to become more common with global warming do not only wreak havoc on land, the runoff from these increasingly severe storms is also threatening Hawaii’s coral reefs. (Arizona State University’s Center for Global Discovery and Conservation Science, Allen Coral Atlas via AP)

HONOLULU — As muddy rainwater surged from Hawaii’s steep seaside mountains and inundated residential communities last month, the damage caused by flooding was obvious — houses were destroyed and businesses swamped, landslides covered highways and raging rivers and streams were clogged with debris.

But extreme rain events predicted to become more common with human-caused global warming not only wreak havoc on land — the runoff from these increasingly severe storms also threatens Hawaii’s coral reefs.

“These big events are the ones that have the greatest damage because they are the ones that put the most sediment and nutrients out onto the reef,” said C. Mark Eakin, senior coral advisor to the National Oceanic and Atmospheric Administration and the former director of the agency’s Coral Reef Watch program.

A warmer climate tends to amplify existing weather patterns, said Hawaii’s state climatologist, Pao-Shin Chu, noting the islands have an overall wet climate and that powerful storms are expected to become more frequent.

“Given this climate change or global warming, as we have seen over the last hundred years, the atmospheric water vapor pressure is increasing,” said Chu. “We have some evidence showing that we already have some increasing, very intense rain.”

Coral reefs make up much of Hawaii’s nearshore ocean ecosystem and are critical to the state’s economy.

Hawaii’s reefs protect populated shorelines from massive ocean swells and storm surges from tropical storms — a benefit the U.S. Geological Survey valued at more than $860 million a year.

Adding tourism, fishing, cultural value and other factors, the state’s reefs are worth more than $33 billion, according to a NOAA-funded study.

March’s flooding was caused by a weather system that stalled over the islands and brought two weeks of rain, much extremely heavy.

On Oahu’s North Shore, “a very large flood wave” rushed down from the mountains and flooded the town of Haleiwa, said National Weather Service hydrologist Kevin Kodama.

“That’s a big challenge in Hawaii, where we have small, steep watersheds,” Kodama said. “Most of the basins in the state will produce flash flooding.”

Last month had 11 flash flood events and was the wettest March in 15 years, he said.

The runoff problem is multifaceted. Deforestation and grading on construction sites and farms lead to increased runoff. Feral animals such as goats, pigs and deer clear vegetation, causing erosion and excessive sedimentation on reefs. And constant, low-level runoff carries gasoline and oil from roadways, household chemicals, trash and pesticides into the ocean.

Any significant change in ocean conditions, such as an influx of fresh water alone, can harm coral health. Contaminants and soil from land accumulate on reefs and can smother and kill the coral. Scientists say suspension of material in the water can also block sunlight coral needs to survive.

One of the biggest problems for Hawaii reefs is sewage. There are about 88,000 cesspools throughout the islands, many in coastal areas.

“Cesspools are essentially a hole in the ground where there is no treatment prior to wastewater entering the environment,” said Jamison Gove, a research oceanographer with NOAA who lives on Oahu’s North Shore.

Cesspools leak into groundwater — and with heavy rains, they overflow and send pathogens and other harmful contaminants into the ocean.

In the town of Pupukea, where professional surfers compete at the famed Banzai Pipeline reef break, more than 330 million gallons of wastewater enters the ocean each year — enough to fill hundreds of Olympic size swimming pools.

On the North Shore during the recent flood, “brown, polluted water just blanketed the entire town,” Gove said. “You could just smell it everywhere.”

More than half the state’s cesspools are on the Big Island, home to some of the state’s most expansive and pristine coral reefs. And Gove said some areas have shown a clear decrease in coral cover where sewage routinely enters the ocean.

A reef off the town of Puako — an extensively monitored location — has seen significant losses, he said. Coral cover there has declined by about 70% since 1975.

“This is probably one of the more dramatic examples since coral cover is not this high in a lot of places,” he said. “But since we don’t have this type of data everywhere, we can’t say for sure this isn’t a more common story.”

NOAA is providing data on the issue to the state, and efforts to remove cesspools and change infrastructure to slow and distribute floodwater could help Hawaii’s reefs.

The state has banned cesspools in new construction and is attempting to remove the existing ones by 2050.

Although coral reefs worldwide face threats from global warming, including marine heatwaves that bleach and kill coral, storm runoff could prove a more serious and immediate threat to reefs in Hawaii.

“In Hawaii, I would rate runoff much higher than marine heatwaves in driving coral decline,” said Greg Asner, director of the Center for Global Discovery and Conservation Science at Arizona State University.

In 2019, Asner and his team used imaging technology on aircraft coupled with satellite data to create new detailed maps of all living coral in the Hawaiian Islands. The data, now being used by federal and state scientists, shows a correlation between land-based pollutants from runoff and coral health.

“More runoff impacts reefs, mostly by mobilizing more chemicals and sediment on land,” Asner said. “Increased chemical pollution and sedimentation is a major driver of coral decline.”

March’s floods were not the first of their kind.

A 2018 rainstorm on Kauai caused widespread flooding that cut off a community for weeks. The storm set a new U.S. record for rainfall in a single day with nearly 50 inches.

Ku’ulei Rodgers, a coral reef ecologist at the University of Hawaii’s Institute of Marine Biology, studied that 2018 flood as well as a 2002 flood in the same area. The 2002 rains swept earth from a construction site into the sea and “killed almost an entire reef,” Rodgers said.

After the 2018 flood, a review found fish abundance on a nearby reef had been reduced by 20% and urchins, which help clean reefs and keep coral healthy, were reduced by 40%.

When making policy decisions about how to safeguard reefs, Rodgers said, it’s important to understand that land and oceans are intertwined.

“(Native) Hawaiians knew there was a connection between the two because whatever they did upland would affect their fishing downstream,” she said. “The better the watershed, the better the reef and vice versa.

7 Comments
  1. Joshua Beadle April 19, 2021 8:10 am Reply

    Yah, we know Hawaii is basically a Third World nation environmentally. Now what? Where are the true Hawaiian’s demanding their elected leaders to uphold the Clean Water Act? You can’t blame this total environment destruction on the Howleeez. It’s your State – elect leaders who are defenders of the natural world.
    Related: the EPA shut down their Hawaii Office since it was so corrupt. Beyond repair. All enforcement has to come through San Francisco. That’s some Third World “stuff” right there.
    Time for Hawaiians to look in the mirror.


  2. Reefer Madness April 19, 2021 8:17 am Reply

    Many of the toxic poisonous chemicals going into our reefs as runoff by cesspool, and sewage plants pumping wastewater treated or only partially treated as sewage into the ocean, is from the toxic chemicals and the carcinogenic cancer causing petrochemicals (whose source is oil wells and coal mines as coal tar) that are in every food in our grocery stores polluting the people before polluting the reefs.

    Does fresh water alone from storms suffocate the reefs seawater environments more than toxic runoff? It would seem the reefs would have adapted to freshwater inundation by storms over the millions perhaps, even billions of years, unlike modern humanities’ cause of newborn untested chemicals in the environment, just like the untested vaccines being hoodwinked on the population, the same toxic pollutants in the vaccines excreted into the toilets of the vaccinated, the toxins and unknown genes, chimpanzee virus, blood clotting chemicals going down the sewer pipes on their Where you way to the ocean reefs.

    It’s Terrible…!

    Maybe it’s time to burn sewage and let the Tradewinds take the “burn” offshore past the reefs and the inshore marine habitat.

    Authorities could start with the leeward side, out past Kekaha, and burn up the GMO and Ag chemical land and seed crop poisons first and then build sewage incinerators.

    Home and Hotel sewage could be pumped into waiting enclosed tanks of appropriate size to be hauled to the incinerators at locations best suited for free air disbursement.

    Cesspools could end “tomorrow “, equipping homes with tanks just bigger than propane tanks for frequent haul out.

    Solids and liquids could be separated and filtered appropriately so only water went back into the earth.

    Chemicals in soaps, and whether or not for dishes, showers, shampoos, and the myriad types of “beauty” chemicals women put on their bodies daily, need to become of non toxic non polluting contents, and while we are at it might as well restrict the toxic carcinogenic chemicals in the food, those go down the toilet on their way to your favorite beach water.

    While this may step on the financial toes of the medical, pharmaceutical, and chemical industries, they could finally convert to teaching and promoting Health and Wellness, instead of treating, managing, and perpetuating diseases, many of which are caused by the side effects of the toxic chemicals used in their businesses.

    Remove the Cause instead of Treating the Effects. A need whose time has come.


  3. Mailman Mike April 19, 2021 9:52 am Reply

    Stop with the global warm myth. The waters around Kauai are still much cleaner than back in the 80s when there was a brown band around the island. Not to mention our roads covered with red mud from the cane trucks.


  4. Nice April 19, 2021 11:33 am Reply

    Jeez…human caused global warming? Who said that “experts” whos funding come from creating problem and claiming to have the solution. Look through fossil records. the earth has been in states of heating and cooling over millennia.


  5. kannaka__oi April 19, 2021 11:34 am Reply

    In this last rain the amount of dirt that came out from Kukuiula is criminal. Not since the mass grading they did in the 80’s has it been so bad. Govt needs to revisit the measures developers use to get their permits and maintain compliance. Shame on you.


    1. Packbacker April 20, 2021 12:51 pm Reply

      You are right. The quantity of mulch, wood chips and just general dirt that poured out of Waikomo Stream last month is unbelievable. Much of the coral in the bowl just outside of the stream was covered and has probably smothered. Tons of the mulch/wood was removed (mostly by divers) from the shore and the boat ramp at Koloa Landing. This single event caused a massive amount of damage. The rain/runoff itself is not the issue — it is instead the dirt and crap that the water carries out.


  6. Colin McCleod April 19, 2021 2:42 pm Reply

    What a load…flood events have been occurring ever since the earth was born several billion years ago.
    Islands erode and coupled with plate tectonics they slowly just go away.
    A look at the Amazon outflow shows the same thing.
    Colin McCleod


Your email address will not be published. Required fields are marked *

*

By participating in online discussions you acknowledge that you have agreed to the TERMS OF SERVICE. An insightful discussion of ideas and viewpoints is encouraged, but comments must be civil and in good taste, with no personal attacks. If your comments are inappropriate, you may be banned from posting. To report comments that you believe do not follow our guidelines, send us an email.