Climate change: sea level rise forecasts surprisingly accurate
Satellites have been measuring sea levels around the world for just over 30 years. A comparison with the forecasts for its rise now shows how good they were.
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Predictions made three decades ago about sea level rise as a result of man-made climate change "were remarkably close to what has happened since". This is the result of an analysis of earth observation data containing information on sea level since the mid-1990s, reports Tulane University in New Orleans. Earth observation satellites have observed a rise in sea level of nine centimetres since 1996; in the second assessment report of the Intergovernmental Panel on Climate Change (IPCC) in that year, eight centimetres was given as the most likely value. At the same time, the contribution of melting ice sheets was underestimated by two centimetres.
Comparison as the "ultimate test" of predictions
As the group led by Torbjörn Törnqvist from the Institute of Earth and Environmental Sciences explains, a new era in the study of sea level began in the early 1990s. Earth observation satellites launched at that time were able to determine it with unprecedented precision and have shown that it has risen by around three millimetres per year worldwide since then. It is also only thanks to these instruments that we know that the rise has recently accelerated. It is only thanks to this measurement data that the ultimate test of predictions on man-made climate change is even possible –, comparing them with what is actually happening. This also helps with adapting to the associated changes.
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"We were quite amazed at how good these predictions were," says Törnqvist now. It should not be forgotten how unsophisticated the climate models of the time were compared to what is available to us today: "For anyone who doubts the role of humans in climate change, this is one of the best proofs that we have understood for decades what is really going on and that we can make credible predictions." His team now also points out that current predictions even raise the – still unlikely – possibility that catastrophic ice sheet collapses are imminent before the end of the century, with consequences for low-lying coastal areas. The research paper itself has now been published in the scientific journal Earth's Future.
(mho)
