Forget Florida or California – New Study Shows 10% of Louisiana May Disappear

When I was growing up, there was a song about the earthquakes in California, and how we would have to ‘tie up the boats in Idaho’ after ‘the big one’. In the last 10 or so years, the rather impressive pictures showing sea life in Florida fresh water swimming pools near the ocean, attesting to the increase in sea level makes the warnings of global warming real for many.

After the havoc wreaked by hurricane Katrina, and the less than ideal conditions in the altitude of New Orleans, many wondered why people even bother with trying to oppose the inevitable changes in store for that state.

An article in Science News, Losing Louisiana how a full 10% of the state may fall victim to the rising sea, and the sinking earth.

Residents of Louisiana, take note: If engineers don’t divert sediment-rich waters from the Mississippi River to help replenish a sinking river delta, about 10 percent of your state will slip beneath the waves by the end of this century. However, even if the engineers do try to abate the subsidence, the Mississippi doesn’t carry enough sediment to offset more than a small fraction of that loss, a new analysis suggests.

Over the past few centuries, about a quarter of the wetlands in the Mississippi River delta have been lost to the ocean, says Harry Roberts, a marine geologist at Louisiana State University in Baton Rouge. Several factors have contributed to that loss, he notes, including sea-level rise and the settling of land as ancient sediments gradually become compacted under their own weight. Now, Roberts and colleague Michael Blum — now at the ExxonMobil Upstream Research Company in Houston — use computer models to estimate the effect that these processes will have on the Mississippi delta in the next few decades. The news, reported online June 28 in Nature Geoscience, isn’t good.

Tidal gauges at Grand Isle, La. — near the tip of the Mississippi delta, where river-dumped sediments lie about 60 meters thick — indicate that land there is sinking as much as 8 millimeters each year. At Baton Rouge, about 250 kilometers upstream, sediments are thinner and the land subsides up to 3 millimeters per year. In Roberts and Blum’s new analysis, regions between those points sink at intermediate rates.

Not only is the land sinking, but the sea is also rising. Scientists on the Intergovernmental Panel on Climate Change report that since 1993, sea level has risen about 3 mm/yr. That rate is expected to accelerate as the planet’s climate warms, heating Earth’s surface waters and causing them to expand, says Roberts. The melting of land-based ice such as glaciers will also contribute. So, the researchers presume — conservatively, Roberts says — that in the year 2100 sea level will be rising 4 mm/yr.

There have been several programs on PBS concerning the long term fate of the area, and there are plans that would at least partially eliminate the problem, as well as return some of the wetlands for wildlife of the area, which are becoming harder and harder to view, as their habitat is systematically eliminated by the combined devastation.

the lower state border may not look exactly like this in a few decades

Will the nation (or just the state of Louisiana) take the problem to heart in time? The changes needed become more Herculean with each passing year, yet, if change comes now, it can be stemmed.

the loss of wetlands is changing the shape of the state yearly, making what was, recede from both map and memory

Will we show intelligence, and change current behaviors, or will the total area of Louisiana continue to drop, year after year?

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