During the 20th century, sea levels along the highly populated U.S. Mid-Atlantic coastline between New York and Virginia rose faster than in any other century during the past 4,300 years, according to a new study. And as those sea levels continue to increase as a result of global warming and local land elevation changes, the risks of coastal flooding will dramatically escalate.I wonder how we measured sea level 4,300 years ago? And who'd of thought that local land elevation changes could be caused by global warming? But I'm not surprised, really.
The study, by geoscientists at Rutgers and Tufts Universities and published in the new journal “Earth’s Future,” took a comprehensive look at the history of sea level in the Mid-Atlantic, combining sediment records of prehistoric sea level with modern data, which includes readings from tide gauges and satellite instruments. The result is one of the most in-depth examinations of past, present, and future sea level rise of any region in the U.S.
An older (2005?)GPS satellite study showed ocean levels varied from expectations by 75-150 feet, (IIRC), because of local gravity fluctuations. Higher local gravity means lower sea levels. Lighter sediment, rock, and magma underlying the ocean means higher sea levels.
The study found that a 7.87-inch global sea level rise during the 20th century, which was largely driven by manmade global warming, caused Hurricane Sandy to flood an additional 27 square miles compared to what it would have if the storm had struck in 1880 when sea levels were lower. Using figures from Climate CentralÂ’s sea level rise database, the researchers found that sea level rise exposed an additional 83,000 people to coastal flooding, with about 45,000 in New York City and the rest in New Jersey.How many of those 83,000 people came after 1880? Maybe the problem is too many folks too close to the water's edge!
While the U.N. Intergovernmental Panel on Climate Change (IPCC) projected that global mean sea level rise for 2081-2100 will likely be between 10-to-32 inches, those numbers mean little to local policymakers, who must make decisions based on local sea level rise rates that often differ from the global average.
The IPCC, you'll recall, took "big reductions in Himalayan glaciers by 2350" (from a 1989 hydrology study, by the way), to "Himalayan glaciers disappearing by 2035".
Those differences are the result of several factors, including ocean currents that can cause faster or slower rates of sea level rise in some areas, groundwater depletion, which can result in sinking land, and gradual post-ice age adjustments of the land.
Post-ice age adjustments would be up, as the ground rebounds after having a mile of ice removed. I think the author overlooks the rebound, below.
In the Mid-Atlantic region, it turns out, all three of these factors are conspiring to accelerate sea level rise. Every part of the region saw the level rise at a faster rate than the global trend, the study found. In fact, that rate since the early 1900s was nearly double the global average.
So ground rising now causes sea levels to rise? Ask me if I am surprised!
Locations that sit atop a coastal plain, such as the Jersey Shore, are seeing the fastest rates of sea level rise compared to those Mid-Atlantic coastal locations that are built on top of bedrock, such as New York City, since the geology of the coastal plain features more settling of the land from groundwater depletion and long-term sediment compaction. Other studies have also identified the Mid-Atlantic as a so-called “hot spot” of sea level rise, but the new research provides more statistical proof that modern sea level rise in this region is outpacing even periods from several thousand years ago.
We need more money to improve our infrastructure to protect us from MMGW. More boodle!
Even the Federal Emergency Management AgencyÂ’s newest flood elevation data, released this year and used to help determine federal flood insurance requirements, failed to include sea level rise projections.
Well! If FEMA is not worried, why should we get all hot-and-bothered?