more hurricanes coming if hawaii loses its ‘cold wall’

david boynton photo of rain clouds on waialeale

Who knew Hawaii was protected from the eastern Pacific hurricane factory by a wall of cold water just east of the island chain?

No one thought to check if this 'cold wall' would survive global warming...until two ecologists from the Fish & Wildlife Service started working with climate models.

Reporting on a remarkable collaboration between island conservationists and climate modelers, Teresa Dawson zeros in on how and why Hawaii's storm and rain patterns are destined to change...perhaps dramatically (via environment hawaii).

Says Stephen Miller, co-author of a recent presentation at the HI Conservation Alliance conference, “We were, at every step in the process, staggered at what we were seeing.”

Miller's report focused on sea surface temperature, the potential for storm generation, as well as changing patterns of precipitation.

According to Miller, most storms that hit Hawaii originate in the eastern Pacific storm basin and tend to dissipate when they hit cooler waters (about 26 degrees C) east of the island chain. When Hawai`i does get hit, it’s usually because it slipped around that wall of colder water.

Meanwhile, the IPCC has stated that the sea surface temperature around Hawaii will increase 1.5 degrees C at a minimum, and Miller finds that the number of storms reaching Hawaii doubled with only a 0.3 to 0.4 degrees C change in sea surface temperature.

According to Miller, climate change impacts on cloud formation and rainfall also imperil Hawaii’s ecosystems. As the air temperature at sea level increases, the air mass will have to rise to a higher elevation in order to cool to the point that it forms clouds. Miller predicts that a temperature increase of 1.5 degrees C would push the cloud base up from 600 meters to about 831 meters.

Thus, says Miller, “the mountain area that produces rain will be reduced,” and less rain in a warmer environment could increase the evapotranspiration rate, as well."

Based on Miller's assumptions of a more elevated cloud base, Kauai could see a reduction in its cloud-producing area of from 34-79 percent decrease, while Lana`i and O`ahu could see their clouds disappear altogether.

Net-net, it looks like the cold wall could disappear and the cloud base will rise. So, we can look forward to more storms and less rain.

Wot's even more staggering is the deafening silence following Miller's HCA presentation.

At the conference, writes Dawson, Miller urged the conservation community to evaluate, design and implement conservation programs that address the predicted impacts of climate change.

Miller notes that he has received no feedback from resource managers since he presented his results at the conference. “None. Literally, none. I’m not sure why, but no one commented after the talk,” he says.

Dawson's piece on Hawaii's climate change prospects represents a first of sorts. 'Tis the first time I can recall when the venerable Environment Hawaii leads with a global warming story.

[Ed.: Actually, editor Pat Tummons notes that this is the 4th climate change cover. Says Tummons, "our first cover was in July 1999 (on the state's climate change action plan"),  followed by another in August 1999, on the effect of warming seas on corals. In January 2001 we had another cover on the effect of climate change on endangered bird habitat."  My bad!]

Keep it coming!

Published by Ken on September 29th, 2007 tagged Climate Change, HI-specific

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