Because we live on a string of islands, it just makes sense to keep track of how fast the sea is rising.

This is a good news, bad news story.

The bad news is, yes, the sea levels around Hawaii are rising. More water means less beach.

The good news is that the state and the University of Hawaii are both watching the water levels and making some precise predictions about what it means.

"We found that increased sea level rise (SLR) causes an average 1620 feet of additional shoreline retreat by 2050, and an average of nearly 60 feet of additional retreat by 2100," said Tiffany Anderson, the lead author of a new report from UH-Manoa’s School of Ocean and Earth Science and Technology.

The new wrinkle in the report is that the state’s Department of Land and Natural Resources helped put together the funding for the report.

"In a nutshell: the study was funded by a combination of state and federal research dollars. So I would say we are getting strong support," reported Chip Fletcher, associate dean at SOEST and co-author on the new report.

Using historic photographs and up-to-the-minute measurement techniques, the UH researchers were able to map out the estimated sea level rise across Hawaii’s beaches (http://goo.gl/PaXvcn).

Using that information, the state’s DLNR reports that beaches are shrinking.

"On Oahu, 10.7 miles of beach has been narrowed by shoreline hardening and 6.4 miles has been lost. This is 24 percent of the 71.6 miles of the original sandy shoreline on Oahu," according to the DLNR webpage.

The state and UH came up with precise maps of every beach with details of how much erosion will take away (http://goo.gl/Cj8etc).

It is serious enough that the beach loss at Lanikai is already estimated to have caused 4,000 feet of beach to disappear.

The UH report from the UH Hawaii Sea Level Center explains that the sea level rise will continue, and the results are not good.

"In Hawaii, sea level rise resulting from global warming is a particular concern. High seasonal waves, hurricanes, and tsunami will penetrate further inland as the water level increases. The coastal groundwater table, which rises and falls with the daily tides, will crop out above ground level creating new wetlands, changing surface drainage, and producing widespread flooding especially when high tide is coincident with heavy rainfall. Coastal erosion will increase," the report warns.

The UH research shows that between 2040 and 2050, the Hawaii sea level will rise 1 foot. By 2050 and 2070, a 2-foot rise is expected.

By then, the UH researchers say, Waikiki will have declined and tourism will have to move to either the west or windward side of Oahu.

Between 2070 and 2090, the seas will have risen 3 feet.

"Most coastal segments where homes still exist in their early 21st century footprints will be protected by seawalls but the wave splash and salt air (are) likely to make many of these locations run-down and relatively undesirable neighborhoods; additionally, the persistence of standing water in most coastal plain neighborhoods also make these undesirable places to invest," says the UH report.

So as it turns out, even the good news is bad news.

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Richard Borreca writes on politics on Sundays, Tuesdays and Fridays. Reach him at rborreca@staradvertiser.com.