USGS reports sea-level rise accelerating in Atlantic coast of North America

Rates of sea level rise are increasing three-to-four times faster along portions of the U.S. Atlantic Coast than globally, according to a new U.S. Geological Survey report published in Nature Climate Change.

Since about 1990, sea-level rise in the 600-mile stretch of coastal zone from Cape Hatteras, N.C. to north of Boston, Mass. — coined a “hotspot” by scientists — has increased 2 – 3.7 millimeters per year; the global increase over the same period was 0.6 – 1.0 millimeter per year.

Based on data and analyses included in the report, if global temperatures continue to rise, rates of sea level rise in this area are expected to continue increasing.

The report shows that the sea-level rise hotspot is consistent with the slowing of Atlantic Ocean circulation. Models show this change in circulation may be tied to changes in water temperature, salinity and density in the subpolar north Atlantic.

Projection of sea-level rise from 1990 to 2100, based on IPCC temperature projections for three different emission scenarios. The sea-level range projected in the IPCC AR4 for these scenarios are shown for comparison in the bars on the bottom right. Also shown in red is observed sea-level (Vermeer 2009).

Though global sea level has been projected to rise roughly 0.6 – 0.9 m (2 to 3 feet) or more by the end of the 21st century, it will not climb at the same rate at every location. Differences in land movements, strength of ocean currents, water temperatures and salinity can cause regional and local highs and lows in sea level.

“This basically adds 8 to 12 inches above the global averages over the next 100 years,” said Peter Howd, a co-author of the report. “Chronic flooding issues now will get worse, that’s what people will see, but local people already know the areas that flood are getting worse,” he said. “It’s not news to them.” “What we will likely see is these areas that almost flood during bad storms now, will chronically flood,” said Howd.

Sea level change. Tide gauge data are indicated in red and satellite data in blue. The grey band shows the projections of the IPCC Third Assessment report (Allison et al 2009).

Maine is at the northern end of the hotspot zone, and impacts are ameliorated because of the rocky coasts, larger tides, and general hilly topography along the shore, said Howd.

The report shows that the sea-level rise hotspot is consistent with the slowing of Atlantic Ocean circulation, which scientists theorize could be related to changes in water temperature, salinity and density in the polar regions of the north Atlantic.

USGS report “Hotspot of accelerated sea-level rise on the Atlantic coast of North America,” was published in the journal Nature Climate Change.

Africa’s savannas are changing into forests

Recent changes in the levels of atmospheric carbon dioxide are forcing the African savannas to change into forests. Researchers believe that by the end of this century large swathes of land that was once savanna could have transformed into forest.

The study hypothesized that fertilisation by atmospheric carbon dioxide is forcing the change. The switch will take place at a different time for each area of savanna, adhering to individual thresholds for carbon dioxide concentration. Previous experimental studies have generally shown that plants do not show a large response to carbon dioxide fertilisation.

Most of these studies were conducted in northern ecosystems or on commercially important species. Only one experimental study has investigated how savanna plants will respond to changing CO₂ concentrations and this study showed that savanna trees were essentially CO₂ starved under pre-industrial CO₂ concentrations, and that their growth really starts taking off at the CO₂ concentrations we are currently experiencing. The potential for regime shifts in a vegetation formation that covers such vast areas is what is making earth system scientists turn their attention to savannas.

This study found that locations where the temperature rise associated with climate change takes place rapidly are locations more likely to switch later to forest as the high rate of temperature increase allows the savanna grasses to remain competitive for longer in the face of rising atmospheric carbon dioxide. But because each region will undergo this catastrophic shift at its own time – unrelated to other neighbouring regions – the cumulative shock to the Earth system will be less.

When viewed on geological time scales, these changes are still rapid explains Steven Higgins, lead author of the study from the Biodiversity and Climate Research Centre and Goethe-University.

The study identified a belt that spans the northern central region of Africa where fire suppression would encourage savannas to transition into forests. If the savannas are set to be replaced by forests, the native flora and fauna of the savannas is likely to disappear. On top of over-grazing, plantation forestry, and crop production, the savanna ecosystem is well on its way out the door.

What is Climate Change

We the people of the 21st Century, have no idea what we are heading into. Little do we realise that soon, no....really soon, we shall have no fossil fuels left to burn and that makes mot people shudder.
We have seen in the past that man has not regarded this planet as his own, but only an instrument to fulfill his own needs. Time and time again, he has mauled and bruised her. Now, she's hitting back and with vengence. Climate Change is inevitable and irriversable after a point.
That brings us to the question.....What is Climate Change?
"Climate change is any long-term change in the statistics of weather over durations ranging from decades to millions of years. It can be manifest in changes to averages, extremes, or other statistical measures, and may occur in a specific region or for the Earth as a whole."
Some parts of the climate system, such as the oceans and ice caps, respond slowly in reaction to climate forcing because of their large mass. Therefore, the climate system can take centuries or longer to fully respond to new external forcings.

The time to act is Today!
We look towards the Copenhagen conference with trusting eyes and hope; for thats all we have.
Our leaders need to understand this and learn...Quick.