Even without satellite data Climate forecasts over 30 years old are astonishing
Early forecasts of global sea level rise from the 1990s are proving to be astonishingly accurate. New satellite data, however, show that The rise is accelerating.
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- Early predictions of sea level rise have proven astonishingly accurate more than 30 years later.
- In 1996, an IPCC forecast stated that global sea level rise would be around 8 centimeters over the next 30 years - very close to the 9 centimeters that actually occurred.
- Satellite data now show that sea level rise has accelerated in recent times.
- Current projections of future sea level rise take into account the possibility of a catastrophic collapse of the ice sheets before the end of this century, although this is uncertain and unlikely.
Long-term climate forecasts from the early 1990s were labeled as scaremongering by lobbyists, oil companies and, in some cases, politicians.
Reality now shows that the predictions of global sea level rise have proven to be astonishingly accurate. This is despite the fact that researchers did not yet have access to today's advanced satellite measurements. This is the conclusion of a new study that has now been published in the scientific journal Earth's Future.
Forecasts about the CO2 content in the atmosphere or the development of the global average temperature, for example, had already proven to be relatively accurate.
"We understand what is really going on"
"The ultimate test for climate forecasts is to compare them with actual developments since they were made, but that requires patience. It takes decades of observation," says lead author Torbjörn Törnqvist, Professor of Geology at the Department of Earth and Environmental Sciences at Tulane University in New Orleans, according to a statement from the university.
The researcher himself is also astounded by the results: "We were quite amazed at how good these early predictions were, especially when you consider how rough the models were back then compared to today". For anyone questioning the role of humans in climate change, this is one of the best proofs that we have understood what is really going on for decades and that we can make credible predictions."
The rise is accelerating
A new era of monitoring global sea level rise began in the early 1990s when satellites were launched to measure sea surface height. These measurements later showed that global sea level rise has averaged around 3.2 millimetres per year since then. Only recently has it become possible to determine that global sea level rise is accelerating.
When NASA researchers proved in October 2024 that the rate had doubled over this 30-year period, it was the right time for the research team to compare this finding with the forecasts that had been made in the mid-1990s independently of the satellite measurements.
Forecast underestimated role of melting ice sheets
In 1996, shortly after the start of satellite-based sea level measurements, the Intergovernmental Panel on Climate Change (IPCC) published an assessment report. It predicted that global sea level rise over the next 30 years would most likely be almost 8 centimetres, which is remarkably close to the 9 centimetres that have actually occurred. However, the report also underestimated the role of melting ice sheets by more than 2 centimeters.
At that time, however, little was known about the role of warming ocean waters and how this could destabilize the marine areas of the Antarctic ice sheet from below. The outflow of ice from the Greenland ice sheet into the ocean was also faster than predicted.
The previous difficulties in predicting the behavior of ice sheets also contain a message for the future. Current projections of future sea level rise take into account the possibility of a catastrophic collapse of ice sheets before the end of this century, although this is uncertain and unlikely. Low-lying coastal regions in the United States would be particularly affected if such a collapse were to occur in Antarctica.
