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Sea Level Rise

Projections and Impacts for New York

aerial view of Long Island
Rising seas and increased storm surges will
put New York's coastlines at risk.

By 2100 scientists project that sea levels along New York's coastlines and estuaries will likely be 18 to 50 inches higher, though they could be as much as 75 inches higher.

In New York's coastal marine counties, home to more than half of the state's citizens, higher sea levels already are intensifying storm surges and flood events. As the seas rise further, coastal communities face growing risks of damage or disruption.

Water expands as it warms, and global mean sea level has been rising since the end of the last ice age. Until the 20th Century the change was small, but then warming sped up as accumulating greenhouse gases trapped more heat in the atmosphere. The oceans grew warmer, making the seas rise faster.

Most of the sea-level rise observed to date has been due to the thermal expansion of warming waters. But today, added water from melting glaciers and land ice sheets is starting to contribute more to sea-level rise than heat-driven expansion of existing seawater. And the Arctic and Antarctic have abundant supplies of land ice yet to melt, all of which will add to sea levels.

Enough greenhouse gases already have accumulated in the atmosphere to lock in sea-level rise for centuries, or even millennia. The longer we continue to emit large amounts of greenhouse gases, the more rapidly the seas will rise.

New York assesses sea-level rise risks and promotes resiliency

ClimAID

A 2011 study, Responding to Climate Change in New York State (ClimAID 2011), provided the first state-scale projections of sea-level rise along New York's coastlines and estuaries. Recent research and sophisticated climate modeling underlie the 2014 Supplement to ClimAID, which reinforces many findings of the earlier report and incorporates observations of recent extreme events intensified by sea-level rise. (Use the ClimAID link at right to access both the 2011 ClimAID report and the 2014 supplement,)

The Supplement's updated projections are a resource for coastal municipalities, businesses and residents trying to prepare for higher sea levels. At this time, the best available sea-level rise projections for New York planners are the projections in the 2014 Supplement to ClimAID.

Community Risk and Resiliency Act

In September 2014, Governor Andrew Cuomo signed the Community Risk and Resiliency Act (see link at right). The statute requires certain state programs responsible for permitting, facility siting and funding to take into account the likelihood of sea-level rise-driven storm surges and floods. It directs DEC to adopt science-based sea-level rise projections by January 1, 2016 and to provide guidance for state agencies. DEC has proposed basing the official state projections on the 2014 ClimAID Supplement.

Sea Level Rise Task Force

In 2011, New York's Sea Level Rise Task Force identified and assessed sea-level rise impacts and threats to the state's coastal communities and natural resources. Its recommendations are the basis for many of New York's current policies.

How rising seas will affect New York

New York's seacoast and tidal portions of the Hudson River are at risk from storm surges and flooding. Damage threatens not only communities and infrastructure, but also critical ecosystems that buffer against floods, protect drinking water and provide habitat for important species.

According to the Sea Level Rise Task Force Report, as seas rise

  • Severe flooding and storm surge damage will increase in frequency and intensity;
  • Beaches and bluffs will suffer increased erosion;
  • Low-lying areas will be inundated; saltwater could infiltrate surface waters and aquifers;
  • Low-lying sewage, wastewater, transportation, communication, and energy infrastructure and systems are at risk of compromise.

Sea-level rise projections

IPCC global sea-level rise findings

The Intergovernmental Panel on Climate Change (IPCC), the United Nations-sponsored, scientific body for the assessment of climate change, projects that global sea levels will rise faster during the 21st century than it has in the decades since 1970.

During the past century, the rate of global mean sea-level rise was about 0.7 inches per decade; observations indicate that the rate of global sea-level rise is accelerating. Based on an assumption of moderate land ice melting, the panel projects a likely rise in global sea levels of 20 to 38 inches by 2100. Its projections are the starting point for developing localized projections, including New York's.

New York State sea-level rise projections

Sea-level rise in New York is expected to exceed the global mean due to certain regional conditions, such as subsidence of coastal lands. Tide-gauge observations indicate that rates of relative sea-level rise in New York State have been greater than the global mean, ranging from 0.86 to 1.5 inches per decade and averaging 1.2 inches per decade over the last century.

[The term relative sea level means the height of the sea relative to a land benchmark. Relative sea level takes into account both global sea level and certain local factors, including subsidence or uplift of the earth's crust in response to groundwater or mineral extraction, changes in glaciation, tectonic activity, sediment consolidation or short-term climatic fluctuations (e.g., El Nino Southern Oscillation). These regional components are described in the 2014 ClimAID Supplement.]

The 2014 ClimAID Supplement projections take into account all known components of sea-level rise, along with advances in physical understanding, climate modelling and computing, and reflect observational data that include Hurricane Irene and Superstorm Sandy. DEC considers these projections to be the best information available for New York planners.

[In the table below, the timeslices refer to decades. For example, the 2020s timeslice refers to the period 2020-2029. Model results are expressed as outcomes or ranges of outcomes at different levels of probability. For example, if 90 percent of the model results occurred below the 90th percentile level, there would be a less than ten percent likelihood of the sea rising by more than that amount. Expressing outcomes in this manner helps decisionmakers assess risks by making it easier for them to take into account both the probability of an event and the severity of the event's consequences.]

It is important to remember that sea-level rise will continue for centuries beyond 2100, so that for many decisions it is not a matter of whether a certain sea-level rise will occur, but when.

2014 ClimAID Supplement Sea-Level Rise Projections

Montauk Point

Baseline (2000-2004) 0 inches Low Estimate (10th Percentile) Middle Range (25th to 75th Percentile) High Estimate (90th Percentile)
2020s 2 in 4 to 8 in 10 in
2050s 8 in 11 to 21 in 30 in
2080s 13 in 18 to 39 in 58 in
2100 15 in 21 to 47 in

72 in

New York City

Baseline (2000-2004) 0 inches Low Estimate (10th Percentile) Middle Range (25th to 75th Percentile) High Estimate (90th Percentile)
2020s 2 in 4 to 8 in 10 in
2050s 8 in 11 to 21 in 30 in
2080s 13 in 18 to 39 in 58 in
2100 15 in 22 to 50 in

72 in

Troy Dam

Baseline (2000-2004) 0 inches Low Estimate (10th Percentile) Middle Range (25th to 75th Percentile) High Estimate (90th Percentile)
2020s 1 in 3 to 7 in 9 in
2050s 5 in 9 to 19 in 27 in
2080s 10 in 14 to 36 in 54 in
2100 11 in 18 to 46 in

71 in


The technical basis for New York sea-level rise projections cited here is found in the report of the Sea Level Rise Task Force and the ClimAid Integrated Assessment for Effective Climate-change Adaptation Strategies in New York State.


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