A rare trio of hurricanes were churning through the Pacific Ocean on Thursday, which scientists attributed to waters warmed by a historically strong El Nino phenomenon.
Tropical Storm Marie strengthened into a hurricane late Wednesday off the coast of Baja California, lining up behind Hurricanes Karina and Lowell -- both rated as major Category 4 -- which were making their way westward across the Pacific.
Three tropical cyclones are "definitely rare to see," Julia Cole, a climate scientist at the University of Michigan, told AFP.
"El Nino warming sets the stage for these storms, which are fueled in large part by warm waters -- when the tropical Pacific is warmer than normal we see an increase in strong storms," Cole said.
Lowell was about 450 miles (725 kilometers) south of Hilo, Hawaii and "is expected to remain a major hurricane for the next several days" as it moves west, according to the National Hurricane Center (NHC).
"Swells from Lowell are likely to cause life-threatening surf and rip current conditions in portions of the Hawaiian Islands during the next several days," the NHC said, adding that its long-range track and intensity forecasts were "more uncertain than usual."
Hawaii is still recovering from the impacts of Hurricane Lala, which brushed past the southern part of the Big Island last month, bringing destructive winds and severe flash floods.
The NHC said late Wednesday that Karina weakened slightly as it moved northwest, but is likely to remain a hurricane for the next couple of days.
Lowell and Karina are trailed to the east by Marie, which was 380 miles southwest of the southern tip of Baja California, generating swells impacting portions of the coast of southwest Mexico and the Baja California Peninsula that will likely spread northward to southern California over the weekend.
Warm waters provide fuel for storms, and El Nino's effect on the atmosphere leaves little vertical wind shear over the Pacific, creating favorable conditions for hurricanes to intensify, said Benjamin Kirtman, an atmospheric scientist at the University of Miami.
"The climate system has significantly warmed over the last 20 years or so," he told AFP.
The sea surface temperature anomaly -- how much warmer the ocean is compared to average -- is already near record high, Kirtman added.
"There's no other way to put it -- it is juicy out there right now."
A similar train of four tropical cyclones took place in 2015, another intense El Nino year, when Typhoon Kilo, Hurricane Ignacio, Hurricane Jimena and Tropical Depression 14E crossed the Pacific at once.
This year's El Nino has a 69 percent chance of becoming the strongest on record, according to the National Oceanic and Atmospheric Administration, and is already unleashing extreme weather across the globe even though it is not expected to peak until October-December.
Peru, the world's largest catcher of anchovy, is facing a devastating blow from warming seas that have gutted production, according to industry officials. In Sudan, El Nino is blamed for delaying crucial rains that have led water levels in the Nile to drop precipitously.
El Nino is the warming phase of a natural cycle in the tropical Pacific known as the El Nino-Southern Oscillation (ENSO), and comes along every two to seven years.
It sets in when east-to-west trade winds ease, allowing warm water which normally piles up in the western Pacific Ocean to slide back east and rise to the surface.
When those warmer-than-average surface temperatures last for a few months, they cause more storms and clouds over the region, which in turn cause ripple effects through the entire global atmosphere: hotter and drier conditions in some places, cooler and wetter in others.
Climate change increases El Nino's impacts. A warmer atmosphere holds more moisture, so El Nino-linked rains can turn more extreme. It also dries out soils, deepening drought where El Nino brings drought.
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