The satellites confirm that the climatic projections of the mid-1990s of sea level elevation were largely accurate, although the melting of ice has been underestimated.
For more than three decades, the satellites followed the world change in sea level, and a recent analysis shows that projections made in the mid -1990s were surprisingly precise. The results, published in The future of the earthA newspaper in free access by the American Geophysical Union, comes from two researchers from the University of Tulane.
“The ultimate test of climatic projections is to compare them with what has happened since they were done, but this requires patience – it takes decades of observations,” said the main author Torbjörn Törnqvist, professor of geology Vokes in the Department of Earth and the Environment.
“We were quite surprised how good these first projections were, especially when you think of the rudeness of the models at the time, compared to what is available now,” said Törnqvist. “For all those who question the role of humans in the change of our climate, here is one of the best evidence that we have understood for decades what is really going on and that we can make credible projections.”
The co-author Sönke Dendorf, David and Jane Flowerree, associate professor in the Department of Science and Engineering of La Rivière-Coastal precision Among these previous models is encouraging, priority today is to refine global data in localized forecasts which can guide planning in vulnerable regions such as southern Louisiana.
Regional variability in sea level elevation
“Sea level does not increase evenly – it varies considerably. Our recent study of this regional variability and processes behind this is strongly based on data from Nasasatellite missions and NoaaOcean monitoring programs, “he said.” The pursuit of these efforts is more important than ever and essential for informed decision -making for the benefit of people living along the coast. “”
A new era of surveillance of the world change in sea level took off when the satellites were launched in the early 1990s to measure the height of the ocean surface. This has shown that the world’s level elevation rate since that time has been on average an eighth thumb per year. It is only more recently, it has become possible to detect that the level of rise in the world’s sea level is accelerating.
When NASA researchers demonstrated in October 2024 that the rate had doubled during this 30 -year period, the time had come to compare this observation with projections that were made in the mid -1990s, regardless of satellite measures.
Comparison of projections and reality
In 1996, the intergovernmental panel on climate change published an evaluation report shortly after the start of sea level measurements based on satellite. He has planned that the most likely quantity of the world’s level of sea level in the next 30 years would be almost 8 cm (three inches), remarkably almost 9 cm which occurred. But that also underestimated the role of the melting of ice caps over 2 cm (about one thumb).
At the time, there was little little to know about the role of warming ocean waters and how it could destabilize the marine sectors of the Antarctic Glass Callow from below. Greenland’s ice cap of the Greenland ice cap in the ocean has also been faster than expected.
The difficulties spent predicting the behavior of glacial caps also contain a message for the future. The current projections of the elevation of the holder level take into account the possibility, although uncertain and of low probability, the collapse of the catastrophic ice foam before the end of this century. Lower coastal regions in the United States would be particularly affected if such collapse occurs in Antarctica.
Reference: “Evaluation of the projections of the IPCC of world change in sea level compared to the pre-satellite era” of Torbjörn E. Törnqvist, Clinton P. Conrad, Sönke Dendendorf and Benjamin D. Hamlington, August 22, 2025, The future of the earth.
DOI: 10.1029 / 2025EF006533
The newspaper was co-written by colleagues from the University of Oslo and NASA jet propulsion laboratory in Caltech.
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