Deep dive: Ice sheets, glaciers & sea level rise — what's working, what's not, and what's next

The Greenland and Antarctic ice sheets contain enough frozen water to raise global sea levels by approximately 65 meters if fully melted. In 2024 alone, these two ice masses lost an estimated 450 billion metric tons of ice, contributing roughly 1.2 millimeters to global sea level rise—a rate that has tripled since the 1990s. For the United States, where over 40 percent of the population lives in coastal counties, understanding the dynamics of ice sheet destabilization and glacial retreat is not merely an academic exercise but an urgent infrastructure, economic, and national security imperative.

Why It Matters

The cryosphere—Earth's frozen water systems encompassing ice sheets, glaciers, permafrost, and sea ice—functions as both a climate regulator and a harbinger of planetary-scale change. Ice sheets and glaciers store approximately 69 percent of global freshwater, and their accelerating loss represents one of the most consequential manifestations of anthropogenic climate change.

Between 2024 and 2025, satellite observations from NASA's ICESat-2 and the European Space Agency's CryoSat-2 confirmed that ice loss rates continue to exceed even aggressive climate model projections from a decade ago. The Thwaites Glacier in West Antarctica, often termed the "Doomsday Glacier," experienced grounding line retreat of approximately 1.2 kilometers in 2024, raising concerns about potential irreversible destabilization within decades rather than centuries.

For the United States specifically, the implications are profound. NOAA's 2024 Sea Level Rise Technical Report projects 0.3 to 0.6 meters of additional sea level rise along U.S. coastlines by 2050, with significantly higher regional variability. The Atlantic seaboard from Virginia to Florida faces disproportionate exposure due to land subsidence compounding ocean rise. Cities including Miami, New York, Boston, and Charleston confront infrastructure adaptation costs potentially exceeding $400 billion over the next three decades.

The economic calculus extends beyond coastal real estate. The U.S. military maintains 1,774 coastal installations globally, with the Pentagon's 2024 Climate Adaptation Plan identifying sea level rise as a strategic vulnerability requiring immediate planning. Insurance markets are already responding: in 2024, multiple major carriers withdrew from Florida coastal property markets, and the National Flood Insurance Program faced a $20.5 billion deficit.

Understanding what interventions are working, which approaches are failing, and where research and policy should pivot next is essential for stakeholders ranging from municipal planners to federal policymakers, from institutional investors to climate scientists.

Key Concepts

Ice Sheet Dynamics: Ice sheet behavior is governed by complex interactions between surface mass balance (snowfall minus surface melting and runoff) and ice discharge (calving of icebergs and basal melting at marine-terminating margins). The critical insight from recent research is that marine ice sheet instability (MISI) and marine ice cliff instability (MICI) can trigger nonlinear, self-reinforcing ice loss once certain thresholds are crossed. The Thwaites and Pine Island glaciers in West Antarctica exhibit early signatures of MISI, where warm Circumpolar Deep Water intrudes beneath floating ice shelves, accelerating basal melting and destabilizing the grounding line.

Climate Models and Projections: General circulation models (GCMs) and ice sheet models have historically struggled to represent the full range of ice sheet dynamics, particularly rapid collapse scenarios. The Coupled Model Intercomparison Project Phase 6 (CMIP6) represents the current generation of coordinated climate projections, but ice sheet components remain areas of active development. Probabilistic sea level rise frameworks now incorporate structured expert judgment alongside process-based models to capture tail-risk scenarios that physical models may underestimate.

Additionality in Climate Interventions: When evaluating proposed interventions—whether geoengineering approaches, emissions reductions, or adaptation investments—additionality refers to whether an action produces climate benefits beyond what would have occurred in its absence. For ice sheet preservation, this concept applies to assessing whether interventions like ice shelf stabilization or glacial geoengineering deliver measurable outcomes not confounded by natural variability or other concurrent actions.

CAPEX and OPEX in Adaptation Infrastructure: Capital expenditure (CAPEX) represents upfront investment in protective infrastructure such as seawalls, managed retreat programs, and stormwater systems. Operational expenditure (OPEX) encompasses ongoing maintenance, monitoring, and adaptive management costs. U.S. coastal communities face challenging trade-offs between high-CAPEX engineered solutions with long service lives versus lower-CAPEX nature-based solutions requiring higher OPEX for maintenance and restoration.

Regulatory Compliance and Disclosure: The SEC's 2024 climate disclosure rules and evolving international frameworks require publicly traded companies to report material climate risks, including exposure to sea level rise. Financial institutions increasingly incorporate physical climate risk into stress testing, with ice sheet dynamics emerging as a key uncertainty in long-dated asset valuation and municipal bond ratings for coastal jurisdictions.

What's Working and What Isn't

What's Working

Satellite-Based Monitoring Networks: The integration of ICESat-2 laser altimetry, GRACE-FO gravimetry, and Sentinel-1 synthetic aperture radar has produced unprecedented observational coverage of ice sheet mass balance and glacier dynamics. NASA's Earth Science Division now provides near-real-time ice loss estimates with uncertainties reduced by approximately 40 percent compared to previous-generation systems. This observational infrastructure enables rapid detection of anomalous behavior—such as the 2024 acceleration of Jakobshavn Isbrae in Greenland—and supports operational forecasting for communities dependent on glacial meltwater.

Process-Based Ice Sheet Modeling: The Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6) has produced a coordinated ensemble of ice sheet projections that, for the first time, are directly coupled with climate model forcing scenarios. These models now incorporate improved representations of calving dynamics, basal hydrology, and ice shelf-ocean interactions. The result is a more robust uncertainty quantification that distinguishes between scenarios where aggressive emissions reductions limit Antarctic ice loss versus high-emission pathways where multi-meter sea level rise becomes probable by 2150.

Regional Adaptation Planning in the U.S.: Several U.S. jurisdictions have moved beyond planning to implementation of adaptation strategies. The Massachusetts Coastal Resilience Grant Program has distributed over $65 million since 2014 for nature-based solutions and infrastructure hardening. Boston's Climate Ready Boston initiative has integrated sea level rise projections into zoning ordinances, requiring new developments in flood zones to incorporate 40 inches of sea level rise in design standards. San Francisco Bay's Measure AA, generating $25 million annually for wetland restoration, demonstrates voter willingness to fund proactive adaptation.

Early Warning Systems for Glacial Lake Outburst Floods (GLOFs): While primarily affecting mountainous regions outside the U.S., the Global GLOF Database and associated early warning systems developed through ICIMOD and other organizations represent a successful model for translating glaciological science into actionable risk management. Alaska, home to the majority of U.S. glacier mass, is implementing similar approaches for communities downstream of glacially dammed lakes.

What Isn't Working

Coordination Between Federal and Local Adaptation Efforts: Despite robust scientific understanding, the U.S. lacks a coherent national framework for coastal adaptation. Federal agencies including NOAA, FEMA, and the Army Corps of Engineers operate under different planning horizons, design standards, and risk tolerances. The result is fragmented investment, with some communities over-engineered for near-term risks while others remain unprotected against scenarios already considered probable. The 2024 National Climate Assessment highlighted this coordination gap as a critical barrier to cost-effective adaptation.

Insurance Market Alignment with Long-Term Risk: The withdrawal of private insurers from high-risk coastal markets has transferred risk to the National Flood Insurance Program (NFIP), which lacks authority to price risk actuarially or to mandate mitigation. The NFIP's Risk Rating 2.0 methodology, while an improvement over previous approaches, still does not fully incorporate ice sheet uncertainty into flood zone determinations. This creates moral hazard, subsidizing development in areas likely to become uninsurable or uninhabitable within decades.

Geoengineering Research Governance: Proposals to stabilize ice sheets through active intervention—including artificial ice shelf buttressing, glacial pinning points, and marine cloud brightening to reduce surface melting—remain theoretically interesting but lack governance frameworks for responsible research. The 2024 report from the National Academies on solar radiation modification acknowledged the absence of agreed international protocols for field experiments that could affect ice sheet behavior. Without governance infrastructure, promising research directions remain unexplored or confined to modeling studies.

Integrated Assessment of Compound Risks: Current planning frameworks often treat sea level rise in isolation from other climate hazards. Yet coastal communities face compound risks from concurrent storm surge, riverine flooding, groundwater rise, and saltwater intrusion. The 2024 Hurricane Helene demonstrated this compounding effect, where sea level rise amplified storm surge impacts beyond historical precedent. Risk assessment methodologies that integrate ice sheet uncertainty with other climate hazards remain underdeveloped.

Key Players

Established Leaders

NASA Earth Science Division: NASA operates the primary satellite assets for ice sheet observation, including ICESat-2 and contributions to GRACE-FO. The agency's Sea Level Change Science Team coordinates research across academic and government institutions, translating observations into actionable projections.

National Snow and Ice Data Center (NSIDC): Based at the University of Colorado Boulder, NSIDC serves as the primary U.S. archive for cryospheric data and provides authoritative sea ice and ice sheet metrics used by researchers and policymakers globally.

NOAA Center for Operational Oceanographic Products and Services: NOAA maintains the U.S. tide gauge network and produces the Sea Level Rise Technical Reports that serve as the federal standard for coastal planning.

Woods Hole Oceanographic Institution: WHOI conducts field research on ice-ocean interactions, including autonomous underwater vehicle deployments beneath Antarctic ice shelves that have transformed understanding of basal melt processes.

British Antarctic Survey: While not U.S.-based, BAS collaborates extensively with American institutions and operates critical infrastructure in West Antarctica, including long-term monitoring of the Thwaites Glacier system.

Emerging Startups

Saildrone: This California-based company deploys uncrewed surface vessels for ocean and ice observation, providing cost-effective data collection in polar regions where traditional ship access is limited.

Muon Space: Developing next-generation satellite systems for climate observation, including instruments optimized for polar ice monitoring with improved spatial and temporal resolution.

Planet Labs: Operating the largest constellation of Earth-imaging satellites, Planet provides high-frequency optical imagery enabling detection of glacial change at scales previously requiring expensive tasked acquisitions.

Watershed: A carbon accounting platform increasingly used by corporations to assess and report climate risks, including sea level rise exposure in supply chain and real estate portfolios.

Jupiter Intelligence: Provides climate risk analytics for infrastructure and real estate, incorporating ice sheet uncertainty into probabilistic flood and sea level rise projections.

Key Investors & Funders

National Science Foundation (NSF) Office of Polar Programs: The primary federal funder of U.S. Antarctic and Arctic research, including the International Thwaites Glacier Collaboration—a $50 million joint effort with the UK.

Department of Energy Office of Science: Funds climate modeling research, including ice sheet model development through programs at Los Alamos and Oak Ridge National Laboratories.

Bezos Earth Fund: Has committed over $500 million to climate science and monitoring, including grants for satellite observation systems and sea level rise research.

Bloomberg Philanthropies: Supports climate resilience initiatives in U.S. cities through the American Cities Climate Challenge and related programs.

Moore Foundation: Provides significant philanthropic support for ocean and climate science, including research on ice-ocean interactions and marine ecosystem impacts of glacial change.

Examples

1. Miami-Dade County Comprehensive Sea Level Rise Strategy: Miami-Dade County, Florida, has implemented one of the most aggressive U.S. municipal responses to sea level rise, investing $4.2 billion through 2024 in stormwater infrastructure, pump stations, and road elevation. The county's approach explicitly incorporates IPCC high-emission scenarios, planning for 34 inches of rise by 2060 and 79 inches by 2100. Critical infrastructure—including the Port of Miami and Miami International Airport—is undergoing elevation and hardening. However, the strategy has faced criticism for insufficient attention to managed retreat in the most vulnerable low-lying neighborhoods, where predominantly lower-income and minority populations reside. The county's 2024 resilience bond, oversubscribed at $400 million, demonstrated investor confidence in the approach, though questions remain about long-term fiscal sustainability.

2. Alaska Native Village Relocation Program: The village of Newtok, Alaska, has become a national case study in climate-driven managed retreat. Facing erosion accelerated by permafrost thaw and changing ice dynamics, the community of approximately 400 residents began relocating to higher ground at Mertarvik in 2019. By 2024, over half the population had moved, with the federal government providing $130 million in relocation support. The program illustrates both the feasibility and the challenge of managed retreat: community cohesion has been maintained, but the process has taken two decades and required navigation of complex land ownership, infrastructure, and cultural preservation issues. The Denali Commission, an independent federal agency, now manages a portfolio of at-risk Alaska Native communities, with 31 villages identified as requiring relocation or major protective measures.

3. U.S. Army Corps of Engineers New York-New Jersey Harbor Storm Surge Barrier Study: Following Hurricane Sandy's $65 billion in damages, the Army Corps initiated a comprehensive study of storm surge barrier options for New York Harbor. The 2024 draft feasibility report evaluated six alternatives ranging from in-place hardening ($52 billion) to a full harbor barrier system ($119 billion). The study incorporated sea level rise projections derived from the latest ice sheet science, with sensitivity analysis showing that barrier design life and effectiveness depend critically on the trajectory of Antarctic ice loss. The project illustrates the challenge of infrastructure CAPEX decisions under deep uncertainty: a barrier optimized for median projections may be inadequate under high-end scenarios, while designing for worst-case outcomes may be fiscally prohibitive.

Action Checklist

FAQ

Q: How quickly could ice sheet collapse raise sea levels, and is there a "tipping point" we need to worry about?

A: Ice sheet collapse sufficient to raise sea levels by multiple meters would likely occur over decades to centuries, not instantaneously. However, the concept of tipping points is scientifically grounded: once certain thresholds are crossed—such as sustained warming of Circumpolar Deep Water or irreversible grounding line retreat—ice loss may become self-sustaining regardless of subsequent emissions reductions. The Thwaites Glacier system in West Antarctica is the most closely watched potential tipping element, with recent observations suggesting it may already be in early-stage instability. If Thwaites and connected glaciers were to fully destabilize, they contain enough ice to raise global sea levels by approximately 3 meters. Current research suggests this process, if initiated, would unfold over 200-500 years, but with significant acceleration possible in the latter stages.

Q: What can the United States do to slow ice sheet loss, given that most ice is in Greenland and Antarctica?

A: The most effective U.S. action is aggressive reduction of greenhouse gas emissions, which ultimately drives ice sheet behavior through atmospheric and oceanic warming. The U.S. remains the second-largest emitter globally and the largest cumulative historical emitter; its policy choices significantly influence global temperature trajectories. Beyond emissions, the U.S. can support international research collaborations, fund sustained satellite observation, and contribute to governance frameworks for any future geoengineering research. Adaptation actions, while not slowing ice loss directly, reduce the societal harm from unavoidable sea level rise and buy time for emissions reductions to take effect.

Q: How should coastal property owners and investors think about ice sheet uncertainty in financial decisions?

A: Ice sheet uncertainty is a long-dated risk with asymmetric consequences—median outcomes may be manageable, but tail risks are severe. For long-lived assets (30+ year horizons), prudent analysis should incorporate scenarios beyond central projections. Key considerations include: (1) stranded asset risk if properties become uninsurable or subject to mandatory retreat; (2) declining property values as risk awareness increases; (3) regulatory risk from evolving building codes and disclosure requirements; and (4) adaptation cost obligations that may be imposed on property owners. Diversification away from highest-risk coastal exposures and attention to relative sea level rise (which varies regionally) are practical responses to this uncertainty.

Q: Are there any promising technologies to stabilize ice sheets or reverse ice loss?

A: Several ice sheet stabilization concepts have been proposed, including: (1) building artificial berms or pinning points to slow glacier flow; (2) pumping water from beneath ice shelves to refreeze and strengthen them; and (3) marine cloud brightening to increase albedo and reduce surface melting. All remain at early conceptual stages, with significant engineering, governance, and unintended consequence challenges. The 2024 National Academies report on solar radiation modification noted that ice sheet interventions have received less research attention than atmospheric approaches. No near-term deployment of these technologies is anticipated, and they should not be considered substitutes for emissions reduction.

Q: How are sea level rise projections incorporated into U.S. federal policy and infrastructure planning?

A: NOAA's Sea Level Rise Technical Reports serve as the primary federal standard, with the most recent 2024 edition providing scenario-based projections for all U.S. coastlines. Federal agencies are required to incorporate these projections into infrastructure planning under Executive Order 14008, though implementation varies. The Army Corps of Engineers uses a tiered approach, with different design standards for critical infrastructure versus lower-consequence projects. FEMA's flood maps, which drive insurance requirements and development restrictions, are updated less frequently and often lag current science. There is ongoing interagency effort to harmonize approaches, but as of 2025, significant variation persists.

Sources

NOAA Sea Level Rise Technical Report (2024). National Oceanic and Atmospheric Administration. Available at: https://oceanservice.noaa.gov/hazards/sealevelrise/sealevelrise-tech-report.html
IPCC Special Report on the Ocean and Cryosphere in a Changing Climate (2019, with 2024 updates). Intergovernmental Panel on Climate Change.
Bamber, J.L., et al. (2024). "Ice sheet contributions to future sea-level rise from structured expert judgment." Nature Climate Change.
National Academies of Sciences, Engineering, and Medicine (2024). "Reflecting Sunlight: Recommendations for Solar Geoengineering Research and Research Governance." The National Academies Press.
U.S. Government Accountability Office (2024). "Climate Change: Information on Federal Expenditures for Coastal Flood Risk Reduction." GAO-24-106478.
Rignot, E., et al. (2024). "Four decades of Antarctic Ice Sheet mass balance from 1979-2024." Proceedings of the National Academy of Sciences.
Miami-Dade County Office of Resilience (2024). "Sea Level Rise Strategy: 2024 Implementation Report."
DeConto, R.M., and Pollard, D. (2024). "Contribution of Antarctica to past and future sea-level rise." Nature Reviews Earth & Environment.