Sea levels are rising 60 per cent faster than estimated
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Sea levels are rising 60 per cent faster than the UN's climate panel forecast, scientists warn.
Satellite measurements show that sea levels are actually rising at an alarming rate of 3.2 mm a year compared to the estimate of 2 mm a year in the Intergovernmental Panel on Climate Change's fourth assessment report (AR4), researchers said.
The researchers, from the Potsdam Institute for Climate Impact Research, Tempo Analytics and Laboratoire d'Etudes en Geophysique et Oceanographie Spatiales involved an analysis of global temperatures and sea-level data over the past two decades, comparing them both to projections made in the IPCC's third and fourth assessment reports.
Results were obtained by taking averages from the five available global land and ocean temperature series.
After removing the three known phenomena that cause short-term variability in global temperatures - solar variations, volcanic aerosols and El Nino/Southern Oscillation- the researchers found that the overall warming trend at the moment is 0.16 degree Celsius per decade, which closely follows the IPCC's projections.
Satellite measurements of sea levels showed a different picture, however, with current rates of increase being 60 per cent faster than the IPCC's AR4 projections.
Satellites measure sea-level rise by bouncing radar waves back off the sea surface and are much more accurate than tide gauges as they have near-global coverage; tide gauges only sample along the coast.
Tide gauges also include variability that has nothing to do with changes in global sea level, but rather with how the water moves around in the oceans, such as under the influence of wind.
The study also found that it is very unlikely that the increased rate is down to internal variability in our climate system and also shows that non-climatic components of sea-level rise, such as water storage in reservoirs and groundwater extraction, do not have an effect on the comparisons made.