Real Science for Real People

Global Warming - Sea Level Rise and the Hackensack Meadowlands

 

By Dr. Beth Ravit

The release of the latest report by the Intergovernmental Panel on Climate Change (IPCC), confirming the reality of Global Warming and its accompanying climate change, comes as no surprise to those of us who live and work in the Hackensack Meadowlands. In the last half-decade we have seen extended periods of drought, abnormally high precipitation, intense storm systems, and some of the hottest temperatures recorded since contemporary records have been kept. The IPCC report focuses on providing scientific evidence that global warming is in fact occurring and it projects models of the future. Because of the global nature of this work, these future projections are somewhat general, and so we thought it would be interesting to take a look at what specific effects global warming might have on a local scale in the Hackensack Meadowlands.

 

First a little background information about the Meadowlands, which were once marshes where fill material was placed so development for residential and commercial projects could occur. Of the original 21,000-acres of marshes comprising the Hackensack Meadows, approximately 13,000-acres received fill material and were subsequently built out. This means that the elevations in many sections of the Meadowlands are quite low in relation to sea level. There are a number of man-made structures in place to protect these low-lying areas, including ditches, berms, and tide gates. Under dry conditions these structures do an adequate job of protecting streets, homes, and businesses from daily high tides in the Hackensack River. Today flooding problems occur when mean high tide coincides with a storm event, which raises the height of the water level during high tide. Global warming will affect the Meadowlands in two significant ways.

 

First, as the atmosphere is getting warmer the waters in the ocean are also warming. As the water warms it expands. At the same time that the existing ocean water is expanding, the glaciers are melting and adding more liquid water into the oceans. The combination of these two physical processes is causing the level of our seawaters to rise dramatically, and at an accelerated rate. The most recent projections from scientists at Columbia University (2006) estimate that sea level in the NY/NJ harbor estuary will rise 8" (25 cm) by the decade of 2020. This additional water will increase the height of water surges that accompany strong storms like nor'easters and hurricanes.

 

In the case of the Hackensack Meadowlands, underlying sea level rise is projected to make the Meadowlands daily high tide water heights increase from around 2 ft. to almost 3 ft., the equivalent of a storm intensity that currently has a 25% chance of occurring. With the higher sea levels being projected, when a major storm event occurs during high tide, the water surge could be 7 ft. or higher. In 1995 a USACE study projected that a Category 3 hurricane could create water surges of over 20 ft. in the NY/NJ harbor - and this study did not include the effect of high tide or waves on top of the water surge. The current infrastructure in the Meadowlands was not designed to protect us from these higher water levels, and as we know, there are already problems with flooding in the District. While we are working to decrease our CO2 emissions to eventually curb global warming, we also need to be planning for the affect that the changed sea levels will have on water control and management within the Meadowlands. This is a regional problem that requires infrastructure modifications now - because 2020 is only 13 years away.

 

For more information, please visit www.ipcc.ch (IPCC report) and www.ccsr.columbia.edu/information/hurricanes/ (NY/NJ sea level rise).