Kauai, Hawaii was doused with 49 inches of rain in a climate change-fueled storm in AprilTrouble in paradise? Kauai got doused with 49 inches of rain in one day, a sign of climate woes to come. Photo credit: Brodie Guy via Flickr.

By Ucilia Wang

A staggering rainstorm on the north shore of the Hawaiian island of Kauai is the latest clue that climate change-related impacts are already threatening the islands. On April 14 and 15, a gauge in Waipa recorded 49 inches of rain in 24 hours. For perspective, the rains from Hurricane Harvey, which inundated the Houston area with up to 60 inches last year, occured over a four-day span.  

The state is still assessing the full extent of damage, and Gov. David Ige recently announced a plan to help farmers who suffered losses during the storm. More than 220 people had to be airlifted to safety by the Army and National Guard as a major road was blocked by landslides. A herd of bison was carried off by the flood waters, with some animals having to be rescued from the ocean.

A group within the National Oceanic and Atmospheric Administration that investigates extreme weather and climate events is analyzing the storm to  determine whether the storm broke the national record for the most rainfall within a 24-hour period.

The current 24-hour record  is 43 inches, set in Alvin, Texas in 1979.

Setting a new record will be just the latest reminder that as the climate warms,  parts of Hawaii are already experiencing bigger torrential rains and will likely see more frequent tropical cyclones. Pao-Shin Chu, Hawaii’s state climatologist and a professor at the University of Hawaii, noted that his research showed that the Big Island has seen more frequent heavy rains in the past 50 years.

“If given a one degree C warming, the atmospheric moisture is expected to increase by 7 percent. With this additional moisture available in the air, it may help trigger heavy downpours if other conditions are right,” Chu said by email.

But is not just heavy downpours and stronger hurricanes, Hawaii’s Department of Land and Natural Resources  published a report last December that examined how sea level rise will affect its residents and economy.

The report estimated that rising seas could cost the state $19 billion in lost land and structures alone by the middle to second half of this century, with Oahu, the most populated island, the most vulnerable to damage. That figure doesn’t include losses that result from flooded roads, utilities and other infrastructure. It also doesn’t even begin to tackle the question of how much extreme weather will cost the state.

The report recommended ways for the state to adapt, such as setting up programs to monitor, communicate and coordinate research. It highlighted zoning measures, financial support, land and water conservation and other steps that  could mitigate the damage.

NOAA’s National Climate Extremes Committee will comb through the data collected by rain gauges in Kauai and assess whether those gauges were performing properly before determining whether the downpour set a national record, said Deke Arndt, chief of climate monitoring at the National Centers for Environmental Information.

The investigation will likely take a few months, and the result could be helpful in policy and business planning, Arndt said.  

“The information is for establishing standards and boundaries for what we know about the climate system. These values can be important for questions about how we design a structure, a process, a business practice or a transportation strategy that can withstand the biggest events,” Arndt said.

Hawaii is already is taking action to reduce its emissions. The state is increasingly generating its own energy from wind and solar because importing fossil fuels is expensive as well as damaging to the climate. And a 2015 law requires the state to meet 100 percent of its electricity demand with renewables by 2045.

Concerns over environmental protection are also reflected in its court decisions. Last December, the state’s highest court affirmed a healthy environment is a right guaranteed by Hawaii’s constitution in an opinion about a case on renewable energy. The ruling allowed the Sierra Club to challenge decisions made by the state’s Public Utilities Commission on a renewable energy contract.  

Climate lawsuits have been filed in other states, such as Alaska, and in other countries asserting similar constitutional rights.