The Intergovernmental Panel on Climate Change (IPCC) projected an annual sea level rise last year in 2011 of 2 millimeters per year. According to new satellite data, there appears to be a stark difference between their projections and reality.
Sea-levels are rising 60 percent faster than predicted, at a rate of 3.2 millimeters per year. Global temperatures, on the other hand, are continuing to rise at the consistent pace which IPCC predicted. The study shows that the increased rate in sea-level rise is not significantly affected by internal variability in Earth's climate system, but is rather reflective of a general trend.
The research was published in the Institute of Physics' journal, Environmental Research Letters, and conducted by researchers from the Potsdam Institute for Climate Impact Research, Tempo Analytics, and Labatoire d'Etudes en Geophysique et Oceanographie Spatiales. They believe that their findings will shed a light on the importance of tracking past predictions, especially since these IPCC predictions are frequently used by decision makers.
Satellite data from the last 20 years on global temperatures and sea-levels were analyzed and compared with the IPCC prediction. The general warming trend of 0.16 degrees C per decade was in line with the IPCC projection. This was even after short-term phenomena were excluded, such as solar variations, volcanic eruptions, and El Nino/Southern Oscillation.
To measure sea-level, satellites bounced radar off the water surface. This is a much more accurate method than tide gauges because the satellites have near-global coverage, and the tide gauges are only along the coast. The tide gauges are also influenced by non-climate factors like ocean currents and wind.
The result of their analysis was a sea-level rise rate that is 60 percent faster than previously predicted.
According to lead author of the study, Stefan Rahmstorf, "This study shows once again that the IPCC is far from alarmist, but in fact has under-estimated the problem of climate change. That applies not just for sea-level rise, but also to extreme events and the Arctic sea-ice loss."
The article was published in the journal, Environmental Research Letters