The global sea level rose by 5.9 mm in 2024, surpassing NASA’s projected annual increase of 4.3 mm, according to satellite data from the Sentinel-6 Michael Freilich mission1. This acceleration, driven primarily by thermal expansion (66%) rather than ice melt (34%), marks the highest annual rise ever recorded2. The findings challenge previous assumptions about the dominance of glacial meltwater in sea level dynamics.
Key Drivers of the Acceleration
NASA’s Jet Propulsion Laboratory (JPL) identified ocean heat uptake as the primary contributor, accounting for two-thirds of the rise3. Record-breaking global temperatures in 2024 caused oceans to absorb 90% of excess heat, exacerbating thermal expansion. While Greenland and Antarctica continued losing ice mass, their combined contribution was proportionally smaller than in prior years4. El Niño conditions further amplified heat distribution in the Pacific, as noted by DasWetter.at5.
Regional and Long-Term Impacts
Coastal regions like Florida and Bangladesh now face “century floods” every 9–15 years, a frequency projected to increase by 20506. The IPCC warns that even with aggressive emissions cuts, sea levels will continue rising for centuries due to delayed ocean response7. Sentinel-6B, launched in 2025, provides higher-resolution data to refine these forecasts8.
Data and Methodology
NASA’s analysis combined satellite altimetry with in-situ ocean temperature measurements. Key findings include:
- 10 cm total rise since 1993, with rates doubling over the past decade1.
- Thermal expansion anomaly: Reversed the historic meltwater-dominated trend observed in earlier decades4.
Conclusion
The 2024 data underscores the urgency of adapting to near-term coastal threats while planning for multi-century sea level commitments. NASA’s ongoing satellite missions remain critical for monitoring and mitigating these changes.
