Almost 100% of accelerated sea level rise. which is significantly less than IPCC projected, is not due to climate change or human emissions, but to local events, a new large scientific study shows. IPCC consistently have overestimated their climate change sea level assumptions.
A comprehensive global analysis of sea level changes has found that current IPCC projections consistently overestimate the actual rates of sea level rise observed at tide gauge stations worldwide. The study, A Global Perspective on Local Sea Level Changes, published in the Journal of Marine Science and Engineering, compared decades of observational data with contemporary climate projections to assess their accuracy.
Researchers analyzed two major global datasets: the Permanent Service for Mean Sea Level (PSMSL) with 204 qualifying locations, and the Global Sea Level Observing System (GLOSS) with 39 locations meeting strict criteria requiring at least 60 years of data and 80% data availability. The selection focused on stations with recent data extending to at least 2015.
The observational data revealed modest global sea level rise rates. PSMSL stations showed a mean rate of 1.4 mm per year with a median of 1.5 mm per year, while GLOSS stations recorded slightly higher rates with a mean of 1.7 mm per year and median of 1.9 mm per year. The majority of locations experienced rises of less than 5 mm per year.
Regional patterns emerged clearly from the analysis. Sea levels actually fell in some areas, particularly around the Baltic Sea and Canada’s West Coast. Conversely, high rates reaching up to 10 mm per year were recorded in specific Pacific locations, along the US Gulf Coast, India’s West Coast, Japan, Thailand, and Australia. Notably, high and low rates often occurred in close proximity, indicating strong local influences.
Statistical analysis for acceleration revealed that only 13% of PSMSL locations and 23% of GLOSS locations showed significant acceleration in sea level rise rates, far fewer than climate projections would suggest.
The most significant finding concerned the systematic overestimation by IPCC projections. The majority of locations showed IPCC-projected rates higher than observed rates. The Atlantic Coast of North America displayed the largest discrepancies, with overestimation ranging from 4-5 mm per year. The North Sea and Baltic regions showed IPCC projection overestimation averaging 2 mm per year, while the Pacific Coast of North America and Australia demonstrated better agreement, with overestimation limited to 1 mm per year maximum.
The researchers identified various local factors explaining observed sea level patterns. Glacial Isostatic Adjustment causes land to rise in former ice sheet locations while sinking in surrounding areas, explaining the falling sea levels around the Baltic. Tectonic activity showed clear effects in Japan, including dramatic changes following the 2011 Tohoku earthquake, where one station dropped over 80 cm. Subsidence from soft soils, groundwater extraction, and sediment loading affected multiple coastal areas.
The study employed rigorous methodology, using tidal analysis rather than simple arithmetic means to calculate sea level changes and incorporating multi-year tidal cycles spanning 8.85 and 18.61 years. Statistical testing included F-tests with Bonferroni correction to account for multiple comparisons across the global dataset.
These findings raise important questions about the reliability of current sea level projections used for coastal planning and climate adaptation. The systematic overestimation across most global locations suggests that IPCC projections may need recalibration based on real-world observed trends. The research demonstrates the critical importance of long-term observational data in validating and improving climate models used for future planning and policy decisions.
