New York Sea-Level Rise Projection Methodology Update

This article describes my response to the New York State Department of Environmental Conservation (DEC) request for comment on its proposed method for development of updated projections of sea level rise along New York State’s tidal coast.  The proposed methodology is consistent with the one-sided science in the Climate Leadership & Community Protection Act (Climate Act).  In this case, however, DEC will actually respond to the comments received.

When DEC adopted the Projected Sea-level Rise regulation in February 2017 I was still working and had not started this blog but I did review the initial projections for sea-level rise. So this is a follow up to my earlier work.  I have been following the Climate Act since it was first proposed. I submitted comments on the Climate Act implementation plan and have written over 300 articles about New York’s net-zero transition because I believe the ambitions for a zero-emissions economy embodied in the Climate Act outstrip available renewable technology such that the net-zero transition will do more harm than good.  The opinions expressed in this post do not reflect the position of any of my previous employers or any other company I have been associated with, these comments are mine alone.


The “Request for Pre-Proposal Comment” document included a background description of the proceeding:

On September 22, 2014, Governor Andrew Cuomo signed into law the Community Risk and Resiliency Act, Chapter 355 of the Laws of 2014 (CRRA). CRRA is intended to ensure that decisions regarding permits regulated by the Uniform Procedures Act and certain expenditures and facility-siting regulations consider future physical risk due to climate change, including sea level rise. Among other things, CRRA amended the New York State Environmental Conservation Law (ECL) to require DEC to adopt regulations establishing science-based State sea level rise projections and to update those projections at least every five years (ECL § 3- 0319). Pursuant to this requirement, DEC adopted 6 NYCRR Part 490, Projected Sea-level Rise1 in February 2017 and is now seeking comment related to the required update.

The announcement for the pre-proposal request for comments stated:

Pursuant to the Community Risk and Resiliency Act, the New York State Department of Environmental Conservation (DEC) is preparing to update the official New York State sea level rise projections as codified in 6 NYCRR Part 490, Projected Sea-level Rise. DEC requests pre-proposal comment on its method for development of updated projections of sea level rise in New York State’s tidal waters. Pre-proposal comments should focus on the method DEC has proposed for development of projections and the resulting projections, and not on application of those projections in regulatory, planning, funding or other decision-making processes. DEC will consider all comments received on its proposed methodology and projections in preparing its final proposed projections for the update to Part 490.

The Climate Act established a New York “Net Zero” target (85% reduction and 15% offset of emissions) by 2050 and an interim 2030 target of a 40% reduction by 2030. The Climate Action Council is responsible for preparing the Scoping Plan that outlines how to “achieve the State’s bold clean energy and climate agenda.”  In brief, that plan is to electrify everything possible and power the electric gride with zero-emissions generating resources by 2040.  The Integration Analysis prepared by the New York State Energy Research and Development Authority (NYSERDA) and its consultants quantifies the impact of the electrification strategies.  That material was used to write a Draft Scoping Plan.  After a year-long review the Scoping Plan recommendations were finalized at the end of 2022 but there was no compilation of responses to comments received.  In 2023 the Scoping Plan recommendations are supposed to be implemented through regulation and legislation.  Note that there is no explicit link between the Climate Act and the projections for sea-level rise in Part 490.  However, I was struck by the overt bias towards extreme values in the proposed methodology that is entirely consistent with the rationale of the Climate Act.

Proposed Methodology Comments

The “Request for Pre-Proposal Comment” document described the proposed methodology to project future sea-level rise:

In its Part 490 update, to ensure consistency in its regulatory and other programs, DEC intends to maintain the projection format used in the original Part 490 regulation. That is, the express terms will provide low, low-medium, medium, high-medium and high projections for three tidal regions of the State, as defined in the original regulation. However, the 2020s projections will be replaced by projections for the 2030s. Projections for the 2050s, 2080s and 2100 will be included, as in the original regulation. As discussed below, DEC proposes to include projections for the year 2150 in the updated regulation and to include a very high projection that reflects a potential low-probability, high-consequence rapid ice melt (RIM) scenario.

I refer readers to the “Request for Pre-Proposal Comment” document for a full description of the proposed methodology.  My comments addressed two aspects of the proposal: how well did the earlier projections do compared to observed sea-level rise since 2017 and whether the choice of the sea-level rise scenarios covers the full range of the possible projections of sea-level rise.

My background includes extensive air quality model development and model verification experience.  As a result, I strongly believe that model predictions should be compared to observations whenever possible.  In this case, the Battery sea-level rise monitoring site, which has the longest record in New York State, can be compared to the previous projections .  According to the documentation:

The mean sea level (MSL) trend at The Battery, NY, USA is +2.91 mm/year with a 95% confidence interval of ±0.08 mm/year, based on monthly mean sea level data from 1856 to 2023. That is equivalent to a change of 0.95 feet in 100 years. (R‑squared = 0.839)

Figure 1 from lists the monthly data and the calculated trend. 

Figure 1: Mean Sea Level at The Battery, NY, USA  (NOAA 8518750, 960-121, PSMSL 12)

I compared the observed data with the DEC Part 490 Table 2 projections from 2017 and the proposed projections for this update.  I downloaded the seasonally-adjusted monthly MSL data from NOAA in CSV format and calculated five-year average MSL and trend values.  Figure 2 plots those values and the Part 490 Table 2 2025 projections from the 2017 regulation and the 2035 Projections in the proposed methodology.  The low projection made in 2017 for the 2020’s is comparable to the last 5-year average observed data but it appears that the trend will still be lower than the projection.  None of the other projections or the 2035 projections using the proposed methodology are credible relative to the observed sea-level rise. 

Figure 2: Observed 5-Year Average Battery Sea-Level Rise and Part 490 Table 2 2025 Projections from 2017 and 2035 Projections in the Proposed Methodology

My understanding of the goal is that DEC wants to ensure that the sea-level projections cover the full range of possible futures that planners should consider.  In that case, then it is obvious that a projection based on extrapolation of the existing trend should be included.   It is easy to do that for the Battery location and the Montauk site also has historical data that can be used.  If the goal is to address flooding in the upper reaches of the Hudson River, for example in Albany/Troy, it gets more complicated.  In that case, rainfall flooding (as in 1984) should be included.  Albany tidal influences are regulated by the Sea Level at the Battery and rainfall flooding is not considered in sea level rise estimates.

My comments also addressed my model verification background concerns.  I pointed out that there is another aspect of the comparison between the projected sea-level rises in the current Part 490 and the observed sea-level rise show in Figure 2.  Weather forecasting skill evaluations use two naïve forecasts: persistence and climatology.  If a forecaster does consistently make a maximum temperature forecast for tomorrow that is better than simply assuming tomorrow’s maximum temperature equals todays and the average climatological temperature, then the forecaster has no skill.  The difference between the observed sea-level rise and the projections does not suggest a skillful forecast using the previous methodology.  The projections for the proposed methodology suggest an even greater sea-level rise than the previous methodology so I think they are even less likely to be skillful.

My comments also addressed DEC’s choice of three of the seven sea-level rise scenarios from IPCC AR 6 projections that are readily available.  According to the “Request for Pre-Proposal Comment” document:

To provide for consideration of a range of possible futures, including potential for low-probability, high-consequence sea level rise scenarios associated with rapid melt of land-based ice, DEC proposes adoption of projections based on a blending of projections associated with three illustrative scenarios:

  • SSP2-4.5 – consistent with Paris Agreement Nationally Determined Contributions
  • SSP5-8.5 – medium confidence – additional amplifying feedback mechanisms
  • SSP5-8.5 – low confidence – includes some rapid ice melt

It is disappointing that DEC proposes to use two illustrative scenarios that rely on the widely debunked SSP5-8.5 emission scenarios.  I referenced a recent “primer” by Roger Pielke, Jr. that describes the out-of-date scenarios of the IPCC.  He explains why the scenario is “obviously, undeniably implausible”:

All of RCP8.5, SSP5-8.5 and SSP3-7.0 assume that the world is going to massively increase consumption of coal in the future. The scenarios project that we will replace natural gas with coal, we will replace nuclear with coal, we will replace wind and solar, we will even chose to abandon gasoline for cars and use coal-to-liquid as fuel. If that sound ridiculous — it is!

My comments recommend that at least one of the SSP-8.5 scenarios be replaced with SSP2-3.4 which Pielke suggests represents a “central scenario based off of current trends and near-term projections”.  I argued that failure to include a plausible emissions scenario means that the Part 490 projections do not represent the full range of projected sea-level scenarios.


As noted by DEC the CRRA amended the New York State Environmental Conservation Law (ECL) to require DEC to adopt regulations establishing science-based State sea level rise.  My comments noted that I am disappointed with the overt apocalypse bias in the Part 490 projection methodology proposed and used in the previous assessment.  In both cases, DEC has chosen to hype the worst-case (“low probability, high consequence) projections by selectively choosing the scenarios that further the narrative of an existential climate crisis.  I don’t think science-based regulatory proceedings should selectively choose scenarios to bias results.  It is inappropriate on one hand to invoke the IPCC “science” as the ultimate rationale for the projections, but then invoke “expert judgement” to maximize the projections by claiming that IPCC did not provide sufficient rigor.  I believe the result is a set of projections that do not provide representative sea-level rise projections for planning purposes.


The proposed methodology guarantees that Part 490 projections of sea-level rise for New York State’s tidal coast will over-estimate potential planning requirements.  The proposed methodology provides biased estimates of sea-level rise through the selective choice of IPCC sea-level rise scenarios that are based on an unlikely emissions future.  I recommended in my comments that the projections include one that extrapolates the observed trend of sea-level rise and one of the IPCC SSP-8.5 emission scenarios be replaced with the SSP2-3.4 emission scenario.

It will be interesting to see how DEC responds to the suggestion to include reasonable lower bound estimates of sea-level rise.  Although DEC typically responds the responses can simply be thank you for your thoughts.  That acknowledgement is more than I received for any of the extensive comments I submitted on the Climate Act Scoping Plan so at least I will know that someone read them.

One final note, this is the start of this proceeding.  It will be interesting to see how they address the application of the projections in regulatory, planning, funding or other decision-making processes.  At that time I expect more parties to participate in the process.  Stay tuned.

Author: rogercaiazza

I am a meteorologist (BS and MS degrees), was certified as a consulting meteorologist and have worked in the air quality industry for over 40 years. I author two blogs. Environmental staff in any industry have to be pragmatic balancing risks and benefits and ( reflects that outlook. The second blog addresses the New York State Reforming the Energy Vision initiative ( Any of my comments on the web or posts on my blogs are my opinion only. In no way do they reflect the position of any of my past employers or any company I was associated with.

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