The heat generated by Climate Change is not causing sea level rise (SLR) rates evenly across coastal areas. Coastal regions north of New York have shown a dramatic rise of 4 inches in 2009-2010.
Figure 2:NOAAs graph shows yearly sea level rise along the northeast North American coast in millimeters per year. The red bar shows how extreme the spike was in 2009. The extreme spike lasted into 2010. Credit: Paul Goddard/University of Arizona Department of Geosciences.
According to NOAA, fluctuations in sea level rise do occur, and trends of sea level rise are occurring globally. But NOAA emphasizes that what it has observed is that regional impacts are the most important way to determine the impact to society.
According to the NOAA report, there are two physical factors that can show why this extreme sea level rise is occurring.
We show that this extreme sea level rise event was a combined effect of two physical factors. First, it was partly due to an observed 30% downturn of the Atlantic meridional overturning circulation (AMOC) during 2009-2010. The AMOC is associated with large-scale currents of the North Atlantic, and it has been shown to impact various climate processes in the North American and European sectors, including coastal sea level. AMOC slowdown during 2009-2010 caused significant short-term changes in ocean temperatures and salinity east of North America, resulting in changes to ocean density and in turn imparting a rise in regional sea level. The extreme nature of the 2009-2010 sea level rise event suggests that such a significant AMOC downturn is very unusual in the past century.
The second contributing factor to the extreme sea level event was due to a significant negative North Atlantic Oscillation (NAO) index. The NAO index measures changes in the near-zonal winds that cross the North Atlantic region and affect much of the region’s weather patterns. The easterly or northeasterly wind anomalies associated with the significant negative NAO index in 2009-2010 acted to push ocean waters towards the Northeast Coast through a process known as "Ekman transport", resulting in further rise in coastal sea levels in addition to that imparted by the AMOC downturn.
Key Findings from the report.
Key Findings
•From 2009 to 2010, coastal sea levels from New York City to Newfoundland jumped by 100 mm on average. This extreme yearly sea level rise rate is unprecedented in the tide gauge record, with statistical analysis suggesting it was a 1-in-850 year event based on past records.
•The extreme sea level rise event was closely related to an observed 30% downturn of the Atlantic Meridional Overturning Circulation (AMOC) from April 2009 to March 2010.
•The significant negative North Atlantic Oscillation (NAO) index in 2009-2010 contributed to the extreme SLR event.
•Climate models project an increase in magnitude and frequency of extreme interannual sea level rise events along the Northeast coast of North America over the 21st century.