Rise in Sea Levels Since 1900
CURRENT TOTAL
Live Counter Notable Facts
(Data shows total rise since 1900 and current rates)
Total Rise Since 1900
Current Rate of Rise
Acceleration Factor
Understanding Rise in Sea Levels Since 1900
This counter tracks the cumulative rise in global mean sea level since 1900, one of the most consequential impacts of climate change. Rising seas threaten coastal communities, infrastructure, freshwater supplies, and ecosystems worldwide, with impacts accelerating as warming continues.
Global sea levels have risen 21-24 centimeters (8-9 inches) since 1900, with about half of this increase occurring since 1993. The rate of rise has more than doubled from 1.4 mm/year throughout most of the 20th century to 3.6-4.6 mm/year in recent decades, driven by accelerating ice loss and ocean warming.
Sea level rise results from two primary factors: thermal expansion as ocean waters warm (accounting for about 42% of observed rise) and the addition of water from melting land ice including glaciers, ice caps, and the Greenland and Antarctica ice sheets (accounting for about 50% of rise).
Sea Level Rise Impacts and Projections
- Current sea level rise is already causing significant impacts through increased coastal flooding, erosion, and saltwater intrusion. High-tide flooding in the U.S. has increased 300-900% over the past 50 years, with some coastal areas now experiencing 'sunny day' floods dozens of times annually.
- The rate of rise varies significantly by region due to ocean currents, land subsidence, and gravitational effects from ice sheet loss. The U.S. East and Gulf coasts are experiencing rates 2-3 times the global average, while some areas in Alaska are actually seeing falling relative sea levels due to post-glacial land uplift.
- Future projections show sea levels will rise 28-55 cm by 2100 under low emissions scenarios, or 63-102 cm under high emissions. However, these estimates may be conservative as they don't fully account for potential ice sheet instabilities that could cause much more rapid rise - up to 2 meters or more by 2100.
- Every centimeter of sea level rise displaces approximately one million people from coastal areas globally. With nearly 900 million people currently living in low-lying coastal zones, continued rise poses one of the greatest migration and humanitarian challenges of the 21st century.
Sea Level Terminology
- Global Mean Sea Level (GMSL): Average height of the ocean surface worldwide, excluding local variations
- Relative Sea Level: Local sea level change including land motion, more relevant for coastal impacts
- Thermal Expansion: Increase in ocean volume as water warms, contributing ~42% of current rise
- Sea Level Equivalent: Amount of global sea level rise from completely melting an ice mass
Components of Sea Level Rise (2006-2018)
- Thermal Expansion: 1.4 mm/year (42%)
- Glaciers & Ice Caps: 0.7 mm/year (21%)
- Greenland Ice Sheet: 0.7 mm/year (21%)
- Antarctic Ice Sheet: 0.4 mm/year (12%)
- Land Water Storage: 0.1 mm/year (3%)
Regional Sea Level Trends
- Western Pacific: +5-6 mm/year
- U.S. Gulf Coast: +4-5 mm/year
- U.S. Atlantic Coast: +3-4 mm/year
- Global Average: +3.6 mm/year
- U.S. West Coast: +1-2 mm/year
Future Sea Level Projections
- By 2050: +25-35 cm (10-14 inches)
- By 2100 (low emissions): +43-84 cm
- By 2100 (high emissions): +63-102 cm
- By 2150 (with ice sheet collapse): up to 5 meters
- Long-term (multi-century): +2-7 meters per °C warming
Data Sources and References
Methodology and Data Collection
Sea level measurements combine satellite altimetry data from missions like Jason-3 and Sentinel-6 with tide gauge records from coastal stations worldwide, providing comprehensive global coverage and long-term trend analysis.
The counter tracks cumulative sea level rise since 1900, incorporating both historical tide gauge data and modern satellite measurements to show the accelerating rate of rise driven by climate change.
Frequently Asked QuestionsAbout Rise in Sea Levels Since 1900
Modern satellite altimetry (Jason-3, Sentinel-6) measures sea level to within a few millimeters, verified against tide gauge records from coastal stations worldwide. The 21-24 cm rise since 1900 and current 3.6-4.6 mm/year rate are well-established by multiple independent measurement systems.
Data comes from NASA Sea Level Change Portal, NOAA Tides and Currents, Global Sea Level Observing System (GLOSS), and IPCC Special Report on Ocean and Cryosphere - the authoritative sources for sea level monitoring and projections.
The rate has more than doubled from 1.4 mm/year in the 20th century to 3.6-4.6 mm/year now. This is driven by accelerating ice loss from Greenland and Antarctica (50% of rise) and thermal expansion of warming oceans (42% of rise). Both factors are intensifying.
Projections range from 28-55 cm under low emissions to 63-102 cm under high emissions. However, if ice sheet instabilities trigger, rise could exceed 2 meters by 2100. Every centimeter displaces approximately 1 million people from coastal areas.
Nearly 900 million people live in low-lying coastal zones. The U.S. East and Gulf coasts experience rates 2-3x the global average. High-tide flooding has increased 300-900% over 50 years. Major cities like Miami, New York, Jakarta, and Mumbai face severe threats.