Global mean sea level has risen approximately 20 centimeters since 1900, and the rate is accelerating. Sea level rise projections from the IPCC Sixth Assessment Report (AR6) show that by 2050, the world can expect between 0.18 and 0.23 meters of additional rise depending on the emissions pathway, widening to 0.38 to 0.77 meters by 2100. For coastal cities, infrastructure, and supply chains, these numbers translate directly into flood risk, insurance costs, and relocation decisions.
Understanding sea level rise projections is essential for any organization with coastal exposure. The data drives regulatory disclosure under TCFD, informs real estate valuations, and shapes long-term infrastructure planning.
What Is Sea Level Rise?
Sea level rise is the long-term increase in the average level of the world’s oceans. Two primary mechanisms drive it: thermal expansion (ocean water expands as it warms) and ice sheet and glacier melt (adding new water volume to the ocean). Both are accelerating under current warming trends.
Unlike other climate hazards that fluctuate year to year, sea level rise is cumulative and essentially irreversible on human timescales. Water added to the ocean from melting ice sheets does not return within centuries. Sea level rise projections therefore represent a floor, not a ceiling: the rise already locked in will continue regardless of future emissions reductions.
Current observations show global mean sea level rising at approximately 3.7 millimeters per year, up from 1.4 mm/year in the early 20th century. The acceleration itself is accelerating, driven primarily by increasing ice sheet contributions from Greenland and Antarctica.
The rate of rise tells the acceleration story. All scenarios start near today’s rate of approximately 4 mm per year, but diverge sharply after 2050.
| Scenario | 2020 | 2050 | 2100 | Change |
|---|---|---|---|---|
| SSP1-1.9 | 4.1 mm/yr | 4.1 mm/yr | 4.1 mm/yr | Flat |
| SSP1-2.6 | 4.1 mm/yr | 4.8 mm/yr | 5.1 mm/yr | +24% |
| SSP2-4.5 | 4.1 mm/yr | 5.8 mm/yr | 7.8 mm/yr | +90% |
| SSP3-7.0 | 4.1 mm/yr | 6.4 mm/yr | 10.9 mm/yr | +166% |
| SSP5-8.5 | 4.4 mm/yr | 7.2 mm/yr | 12.6 mm/yr | +186% |
Median rate of global mean sea level rise. Source: IPCC AR6 WG1.
IPCC AR6 Sea Level Rise Projections
The most authoritative sea level rise projections come from IPCC AR6 Working Group 1, published in 2021. These projections use Shared Socioeconomic Pathways (SSPs) to model different emission futures. The table below shows median sea level rise projections relative to the 1995-2014 baseline.
| Scenario | Description | 2050 Median | 2050 Likely Range | 2100 Median | 2100 Likely Range |
|---|---|---|---|---|---|
| SSP1-1.9 | Net-zero by 2050 | 0.18 m | 0.15 – 0.23 m | 0.38 m | 0.28 – 0.55 m |
| SSP1-2.6 | Sustainability | 0.19 m | 0.16 – 0.25 m | 0.44 m | 0.32 – 0.61 m |
| SSP2-4.5 | Middle of the road | 0.20 m | 0.17 – 0.26 m | 0.56 m | 0.43 – 0.76 m |
| SSP3-7.0 | Regional rivalry | 0.21 m | 0.18 – 0.27 m | 0.68 m | 0.55 – 0.90 m |
| SSP5-8.5 | Fossil-fueled | 0.23 m | 0.20 – 0.29 m | 0.77 m | 0.63 – 1.01 m |
Relative to 1995-2014 baseline. Likely range = 17th-83rd percentile. Source: IPCC AR6 WG1, Table 9.9.
A critical observation: through 2050, all five scenarios remain within a narrow 5 cm band, from 0.18 to 0.23 meters. The ocean responds slowly to emissions changes, so near-term rise is already committed from past warming. The scenarios diverge sharply after 2050 as emission pathways produce different warming trajectories.
By 2100, the gap becomes dramatic: SSP5-8.5 projects 0.77 m versus 0.44 m under SSP1-2.6, a 76% difference. Under a low-confidence scenario that accounts for possible ice sheet instability, the median rises to 0.88 m with a likely range of 0.63 to 1.60 m.
By 2150, projections diverge further: 0.57 m under SSP1-1.9 to 1.32 m under SSP5-8.5, with the low-confidence scenario reaching nearly 2 m.
SSP Scenarios and Sea Level Rise
The SSP scenarios used in sea level rise projections represent different assumptions about global development, energy systems, and emissions policy. Each pathway produces a different warming trajectory that feeds into ocean thermal expansion and ice melt calculations.
SSP1-2.6 (Sustainability) assumes rapid decarbonization, reaching net-zero emissions around 2070. Global warming stays below 2 degrees Celsius. Sea level rise projections under this pathway show 0.19 meters by 2050 and 0.44 m by 2100 due to committed warming.
SSP2-4.5 (Middle of the Road) assumes moderate climate action with emissions peaking around 2040 and declining slowly. Warming reaches approximately 2.7 degrees Celsius by 2100. Most organizations use this scenario as their central planning case for sea level rise projections.
SSP5-8.5 (Fossil-Fueled Development) assumes continued reliance on fossil fuels with high economic growth. Warming reaches 4.4 degrees Celsius by 2100. Sea level rise projections under this scenario are the highest and serve as the stress test for coastal assets. For deeper context on emission pathways, see our guides to SSP scenarios and RCP scenarios.
The components driving sea level rise vary by scenario. Thermal expansion accounts for the largest single share across all pathways. Antarctica contributes roughly the same amount (~0.11 m) regardless of emissions, because its response is locked in for decades.
| Source | SSP1-2.6 | SSP2-4.5 | SSP5-8.5 |
|---|---|---|---|
| Thermal Expansion | 0.14 m (33%) | 0.20 m (35%) | 0.30 m (39%) |
| Glaciers | 0.09 m (20%) | 0.12 m (22%) | 0.18 m (23%) |
| Antarctica (AIS) | 0.11 m (25%) | 0.11 m (20%) | 0.12 m (15%) |
| Greenland (GIS) | 0.06 m (13%) | 0.08 m (15%) | 0.13 m (17%) |
| Land Water Storage | 0.03 m (7%) | 0.03 m (5%) | 0.03 m (4%) |
Median contributions at 2100. Source: IPCC AR6 WG1. Percentages are share of total rise.
How Sea Level Rise Risk Is Assessed
Translating sea level rise projections into location-specific risk requires combining the global projections with local elevation data and tidal conditions. The key metric is freeboard: the vertical distance between a location’s ground elevation and the projected water level.
The freeboard calculation is straightforward:
Freeboard = Elevation – (SLR Projection + Tidal Buffer)
The tidal buffer of 1.5 meters is a standard engineering allowance that accounts for spring high tides (0.5 to 1.0 meters above mean sea level) and storm surge during extreme weather events (0.5 to 1.5 meters). Combined with the sea level rise projection, this gives the effective water level a location must withstand.
| Risk Rating | Freeboard | Interpretation |
|---|---|---|
| Extreme | Less than 0.5 m | Regular inundation likely during high tides and storms |
| Severe | 0.5 to 1.5 m | Inundation during major storm events |
| High | 1.5 to 3.0 m | Vulnerable to extreme storm surge combinations |
| Moderate | 3.0 to 5.0 m | Marginal buffer, risk increases over time |
| Low | Greater than 5.0 m | Sufficient elevation to absorb projected rise plus surge |
Locations more than 50 kilometers from the coast are typically excluded from sea level rise assessments entirely, as they face no direct coastal inundation risk regardless of projections.
Which Areas Are Most at Risk
Sea level rise projections affect coastal regions worldwide, but the impact is not evenly distributed. Low-lying deltaic regions, small island nations, and densely populated coastal cities face the most severe exposure.
In South and Southeast Asia, cities like Mumbai, Dhaka, Jakarta, and Ho Chi Minh City sit on low-elevation coastal plains where even 0.30 meters of rise affects millions of people and billions in assets. India’s coastline is particularly exposed: Mumbai’s western shoreline, the Sundarbans delta, and Chennai’s coast all fall within high-risk zones under current sea level rise projections.
In the United States, Miami, New Orleans, and parts of New York face significant exposure. NOAA data shows that high-tide flooding events along the US coast have already more than doubled since 2000 due to sea level rise that has already occurred.
For organizations with physical climate risk exposure, sea level rise creates compounding effects: it amplifies storm surge heights, increases groundwater salinity, and accelerates coastal erosion, all of which worsen other hazard categories simultaneously.
Sea Level Rise and Business Risk
Sea level rise projections carry direct financial implications across multiple sectors. Real estate valuations in coastal zones are beginning to incorporate sea level rise data, with properties below the 3-meter freeboard threshold seeing measurable price discounts in flood-aware markets.
Insurance is becoming more expensive or unavailable in high-risk coastal areas. Several major insurers have withdrawn coverage from parts of Florida and Louisiana, and similar patterns are emerging in coastal regions globally.
Infrastructure assets like ports, power plants, data centers, and manufacturing facilities built in coastal zones face increasing operational disruption. A flood risk assessment that includes sea level rise scenarios helps organizations quantify this exposure and plan adaptation or relocation strategies before damage occurs.
For organizations reporting under TCFD, sea level rise is a core physical risk that must be assessed under multiple scenarios. The projection data in this article maps directly to the scenario analysis requirements in TCFD recommendations.
Frequently Asked Questions
How high will sea level rise by 2050?
IPCC AR6 projects median global sea level rise of 0.18 meters under SSP1-1.9 (net-zero), 0.19 meters under SSP1-2.6 (sustainability), 0.20 meters under SSP2-4.5 (moderate emissions), and 0.23 meters under SSP5-8.5 (high emissions) by 2050, relative to the 1995-2014 baseline. The likely range spans 0.15 to 0.29 meters across all scenarios.
How much will the sea rise by 2030?
By 2030, global mean sea level is projected to rise approximately 0.09 to 0.10 meters across all emission scenarios. The small range reflects that near-term sea level rise is already committed from past emissions and does not vary significantly between pathways until after 2050.
What is the projection of sea level rise in India?
India’s coastline faces the same global median projections (0.18 to 0.23 meters by 2050, 0.38 to 0.77 meters by 2100) plus regional factors. Mumbai, Chennai, and the Sundarbans delta are among the most exposed areas. Local subsidence in some Indian coastal cities can add 5 to 10 millimeters per year on top of global sea level rise.
What is the difference between SSP scenarios for sea level rise?
SSP scenarios represent different emission pathways. SSP1-1.9 assumes net-zero by 2050 with 0.18 m rise by 2050 and 0.38 m by 2100. SSP2-4.5 assumes moderate action with 0.20 m by 2050 and 0.56 m by 2100. SSP5-8.5 assumes continued fossil fuel use with 0.23 m by 2050 and 0.77 m by 2100. Scenarios converge in the near term but diverge significantly after 2050.
How is sea level rise risk assessed for buildings?
Sea level rise risk for buildings is assessed using freeboard: the vertical distance between ground elevation and projected sea level plus a 1.5-meter tidal buffer. Buildings with freeboard below 0.5 meters face extreme risk, while those above 5.0 meters are rated low risk. Elevation data from NASA SRTM and IPCC projections are the primary inputs.
How much will sea level rise by 2100?
IPCC AR6 projects 0.38 m under SSP1-1.9 (net-zero), 0.56 m under SSP2-4.5 (middle of the road), and 0.77 m under SSP5-8.5 (high emissions) by 2100. The likely ranges are wider: 0.28 to 0.55 m at the low end and 0.63 to 1.01 m at the high end. Under a low-confidence ice sheet instability scenario, rise could reach 1.60 m.
What causes sea level rise?
Three mechanisms drive sea level rise: thermal expansion (ocean water expands as it warms, ~35% of projected 2100 rise under SSP2-4.5), glacier melt (~22%), and ice sheet loss from Greenland and Antarctica (~35% combined). Land water storage changes account for the remaining ~5%. Thermal expansion is the single largest contributor, contrary to the common assumption that ice melt dominates.
How fast is sea level rising?
Global sea level is currently rising at approximately 4.1 mm per year. Under SSP1-1.9 (net-zero), the rate stays flat through 2100. Under SSP5-8.5 (high emissions), it triples to 12.6 mm per year by 2100. The rate has already more than doubled from 1.4 mm per year in the early 20th century to over 4 mm per year today.
Conclusion
Sea level rise projections from IPCC AR6 provide the definitive data for assessing coastal exposure. With 0.18 to 0.23 meters of rise projected by 2050, widening to 0.38 to 0.77 meters by 2100, organizations with coastal assets need to incorporate these projections into risk assessments, disclosure, and long-term planning now. The rise already committed cannot be reversed, making early assessment and adaptation the only practical response.
