sea level rise

Sea Levels Are Steadily On The Rise 2/17/20

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Sea Levels Around The US Aren’t Just Rising, They’re Accelerating Year on Year

CARLY CASSELLA
16 FEB 2020

The worst case scenario for sea level rise in the United States is more than just a dim possibility. It’s becoming more likely.

An annual “report card” for the US coastline shows sea levels are speeding up in most places measured.

“Acceleration can be a game changer in terms of impacts and planning, so we really need to pay heed to these patterns,” says John Boon at William and Mary’s Virginia Institute of Marine Science (VIMS).

Out of the 32 tidal stations monitored from Maine to Alaska, the team detected sea level rise in no less than 27. What’s more, 25 of those locations experienced higher rates of sea level rise in 2019 than in the year before.

The Gulf Coast in Louisiana, and Galveston and Rockport in Texas were at the very top of the list. In fact, Rockport trumped all 32 stations, exhibiting a rate of sea level rise that the authors say would ultimately leave water levels 0.82 metres higher in 2050 than in 1992.

In the end, only five stations around the country experienced falling sea levels, four of which are located in Alaska, where coastal mountains are in the process of forming (whereas, on the east coast, land is generally busy sinking).

“Although sea level has been rising very slowly along the West Coast,” says marine scientist Molly Mitchell, “models have been predicting that it will start to rise faster. The report cards from the past three years support this idea.”

It’s not just the team at VIMS, nor is it just the US experiencing this. The National Oceanic and Atmospheric Administration (NOAA) thinks sea level rise is accelerating around the world, and it’s been doing so since around 2013 or 2014.

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Scott Pena / Flickr / CC BY 2.0

By Paul Brown

The latest science shows how the pace of sea level rise is speeding up, fueling fears that not only millions of homes will be under threat, but that vulnerable installations like docks and power plants will be overwhelmed by the waves.

New research using satellite data over a 30-year period shows that around the year 2000 sea level rise was 2mm a year, by 2010 it was 3mm and now it is at 4mm, with the pace of change still increasing.

The calculations were made by a research student, Tadea Veng, at the Technical University of Denmark, which has a special interest in Greenland, where the icecap is melting fast. That, combined with accelerating melting in Antarctica and further warming of the oceans, is raising sea levels across the globe.

The report coincides with a European Environment Agency (EEA) study whose maps show large areas of the shorelines of countries with coastlines on the North Sea will go under water unless heavily defended against sea level rise.

Based on the maps, newspapers like The Guardian in London have predicted that more than half of one key UK east coast provincial port — Hull — will be swamped. Ironically, Hull is the base for making giant wind turbine blades for use in the North Sea.

​The argument about how much the sea level will rise this century has been raging in scientific circles since the 1990s. At the start, predictions of sea level rise took into account only two possible causes: the expansion of seawater as it warmed, and the melting of mountain glaciers away from the poles.

In the early Intergovernmental Panel on Climate Change reports back then, the melting of the polar ice caps was not included, because scientists could not agree whether greater snowfall on the top of the ice caps in winter might balance out summer melting. Many of them also thought Antarctica would not melt at all, or not for centuries, because it was too cold.

Both the extra snow theory and the “too cold to melt” idea have now been discounted. In Antarctica this is partly because the sea has warmed up so much that it is melting the glaciers’ ice from beneath — something the scientists had not foreseen.

Reuters
 

February 17, 2020  Topic: History  Region: World  Blog Brand: The Buzz  Tags: AntarcticaGlobal WarmingClimate ChangeIce MeltSea Level Rise

How an Ancient Antarctic Ice Melt From 129,000 Years Ago Warns Us of a Future Sea Level Rise

Here’s what we know.

Rising global temperatures and warming ocean waters are causing one of the world’s coldest places to melt. While we know that human activity is causing climate change and driving rapid changes in Antarctica, the potential impacts that a warmer world would have on this region remain uncertain. Our new research might be able to provide some insight into what effect a warmer world would have in Antarctica, by looking at what happened more than 129,000 years ago.

We found that the mass melting of the West Antarctic Ice Sheet was a major cause of high sea levels during a period known as the Last Interglacial (129,000-116,000 years ago). The extreme ice loss caused more than three metres of average global sea level rise – and worryingly, it took less than 2˚C of ocean warming for it to occur.

To conduct our research, we travelled to an area on the West Antarctic Ice Sheet and drilled into so-called blue ice areas to reconstruct the glacial history of this ice sheet.

Blue ice areas are areas of ancient ice which have been brought to the surface by fierce, high-density winds, called katabatic winds. When these winds blow over mountains, they remove the top layer of snow and erode the exposed ice. As the ice is removed by the wind, ancient ice is brought to the surface, which offers insight into the ice sheet’s history.

While most Antarctic researchers drill deep into the ice to extract their samples, we were able to use a technique called horizontal ice core analysis. As you travel closer to the mountains of the ice sheet, the ice that been brought to the surface by these winds progressively gets older. We then were able to take surface samples on a straight, horizontal line across the blue ice area to reconstruct what happened to the ice sheet in the past.

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