sea-level rise: how can we adapt?

Michael OppenheimerPrinceton University

atEPIC Seminar, University of Chicago

14 October 2015

Sea Level Rise: How Can We Adapt?

In collaboration with…

Chris Little (AER),Roger Cooke (RFF),

Nathan Urban (LNAL), Bob Kopp (Rutgers), Ning Lin (Princeton), and others

Current means to

estimate sea level rise

uncertainty is incomplete and already too large for

policy purposes

IPCC WGI AR5

Yet decisions on coastal protection are currently being

made!• Problem of uncertainty and the need for science relevant to decision-

making: what do we advise; what will policy makers find useful?

• Reducing uncertainty: 0.2 vs. 2m implies radically different investments now

• Need for a probabilistic, risk-based approach

• Limits of process-based ice-sheet models in projecting SLR - structural uncertainty

• Currently suboptimal disaster preparedness

• Reducing the risk

Global Mean Temperature, Sea Level Rising IPCC WGI AR5

(1901-1990:1.2 ± 0.2 mm/yr)(1993-2010: 3.0 ± 0.7 mm/yr)

AR5 FAQ 5.2 Fig.1

Key sources of uncertainty/complexity

for decision makers

• Future emissions

• Local vs. global sea level rise

• Ice sheets difficult to model

• Future exposure and vulnerability

Vulnerability + Exposure interact with climate change to produce added Risk

7

Vulnerability:

The predisposition of a person or group to be adversely affected

Exposure:

Being in the wrong place at the wrong time

RISK

Growth in exposure to current 100-yr coastal flooding by 2070

Hanson at al Climatic Change 2011

Can policy makers think ahead?

CourtesySydneyHarris

Political, psychological obstacles to the ideal are large

Extreme episodes have a large impact on policy but..

• Episodes are infrequent

• Memories short

• Planning times are long

• Risk increases continuously

• Political incentives perverse compared to requirements of risk management

Memories are short…

even among those

responsible for risk

management

Hoboken subway station 2012 - - - and 1992

Obstacles to Timely Action

Coastal risk only one of several climate-related risks to urban areas

• Structural density, hard & impermeable surfaces urban heat island, pluvial flooding

• Infrastructure stacked well below as well as above grade enhanced coastal vulnerability

• Impact “hotspots” e.g., smog + heat island

Climate change interacts with all of the above

Extremes: by 2040, hot days currently occurring up to 10% of time increase to up to 30%

(IPCC 2013)

Processes determining global and local sea level change

(after AR5 Fig. 13-1)

No credible Process-Based Model

LOCAL:•Non-uniform ocean processes•Crustal, gravitational, rotational responses to ice sheet loss •GIA•Tectonics, sediment, etc.

Sea Level Projections (Global)(IPCC 2013)

Comparedto 20cm

past 100 years

Unlike temperature,model uncertainty becomeslarger than emissions uncertainty

Local sea level rise - selected NE US locations

High emissions case (RCP8.5)

Kopp et al 2014

Percentile Median 5 95

NYC 96 44 154

Newport 93 43 151

Atlantic City 104 53 163

Norfolk 105 59 158

Global Mean 79 52 121

Sea level rise (cm) year 2100 compared with year 2000

-

~7m

~4m~52mLong Term Hazard –

Trigger?– How fast?

Last time Earth was about two-degrees Celsiuswarmer for sustained period, sea level was 5-10meters higher!

Dynamical behavior of ice sheetsLargely ocean-driven, poorly understood

No adequate model

AR5 Box 5.2, Fi. 1

Diverse results from SeaRise model inter-comparison

from Nowicki et al 2013, Fig 7.

Difficulties: Ice physics, boundary and initial conditions, ice-ocean feedbacksResult: Prospect of a credible continental-scale coupled, prognostic (for these timescales) model remains distant

control yr 100 control yr 100

Variance

Global

NYC

Kopp et al 2014

Flood frequency multiplier for 0.5mglobal mean sea level rise:

Shortens window for recovery from largeand intermediate storms

NYC: uncertainty of +/-O.5m can triple the multiplier

Now consider that frequency of high-intensity TCs increases (in models, NYC)

Cat 1

Cat 2

Cat 3

Cat 4

Cat 5

Preindustrial

Recent

Effect already evident in paleoclimate record, NYC

Reed et al PNAS 2015

Proxy-based + observed sea level change

Change in model-based tropical cyclone flood height (synthetic storm set)

2.25m height: 500yr 24yr

By 2050’s Sandy-like flood becomes 100-yr occurrence even with today’s storms

Current “worst case” hurricane surge for NYC

area isgreater than Sandy’s –now consider that sea level is rising and, in

addition, hurricanes are likely to intensify

Modest amount of rise can make a big difference

SIRR 2013

257 NYC coastal resilience recommendations

The easy part - facilities within floodplain: hospitals, for example

Retrofit existing ones, direct new ones outside

Problem: multiple, overlapping jurisdictions,

politics-as-usual

What about the subway tunnels?

…somebody else’s problem

…And Political Reality

Tunnels: “NYCDOT, therefore, has evaluated a series of potential flood protection strategies, including installing floodgates and raising tunnel entrances and ventilation structures above flood elevations to provide specific protection for sensitive mechanical and electrical equipment, including ventilation, lighting, and safety systems. Subject to available funding…” SIRR

“Progress” (partial reversal of Biggert-Waters flood insurance reform): “Recent victories include.…successfully advocating for reforms to the National Flood Insurance Program to protect New York City residents from punishing rate increases…”One City, Rebuilding Together

But difficult projects do get done - Thames Barrier, London:Simpler jurisdictional issue

After enough damage, even with low resources, some people and governments learn to do better

as risk increases – Can we?

In Bangladesh, concrete bunkers + early warning systems cut death rate in cyclones (Jeff Masters’ wunderblog)

Which scale, and timescale of investment needed?

Some needed policy changes• Integrate “hard (gray)” and “soft (green)” defenses; can USACE evolve?

• Legitimize retreat (revenue issue?) – some progress

• New insurance formats and pricing (risk-based plus vouchers or resilience credits or advanced buyout credit)

• Getting the maps right (vs. current FEMA approach) and update regularly

• New federal/local relationship over resilience funding

• Lowering scientific uncertainty to allow tails to be meaningfully considered in policy

Atlantic City: Speculative atrixPrinceton School of Architecture, Team Leader Paul Lewis

Atlantic City: Proposed transformations to suburban communities Princeton School of Architecture, Team Leader Paul Lewis

Or, floodable structures

Some ideas on insurance reform (courtesy Howard Kunreuter)

• Premiums should reflect risk.

>>>Don’t subsidize premiums – counters need for mitigating risk via advanced reduction on vulnerability and exposure.

• Choice architecture: coordinating risk-based rating with incentives to build resilience in advance.

• Public–private partnerships to assist those who cannot afford to invest in protective measures and to provide financial protection against catastrophic losses for risks uninsurable by the private sector alone.

• Multi-year insurance to provide premium and coverage stability while discouraging policy holders’ cancelling after years of no losses.

On incentives…

● Means-tested vouchers, premium discounts, long term loans in exchange for cost-effective mitigation measures..

•Well-enforced building codes and seals of approval

● Reinsurance and other private sector risk-transfer instruments Federal reinsurance would provide insurers with protection against extreme losses (terrorism model).

•Enforce related rules (banks re flood insurance requirements)

And…

• Probabilize (with scenarios?) exposure and vulnerability as well as hazard to allow a complete risk-based assessment.

(difficult to achieve due to reflexivity)

Given experience, what bet would you take that a rational

approach will prevail? Will politics allow it?