The slowdown in sea-level rise reported over the past decade is due to natural variability in the climate and is not indicative of a slowdown in the effects of global warming, as reported in a study published online in Nature Climate Change. Correcting for this interannual variability gives a sea-level rise rate of 3.3 ± 0.4 mm per year, which is comparable to the rate observed in the 1990s of about 3.1 mm per year.
To separate natural variability from anthropogenic influences, Anny Cazenave and colleagues analysed time-series data of global mean sea level from five prominent research groups that processed satellite altimeter measurements for the periods 1994-2002 and 2003-2011. The data for 2003-2011 shows an average rise in ocean levels of 2.4 mm per year compared with a rise of 3.5 mm per year for the preceding decade, representing a decrease of about 30%. However, the authors note that the largest cause of interannual sea-level variability is the El Nino-Southern Oscillation, which impacts the global water cycle through changes in land water and atmospheric water vapour content. Removal of the natural variability shows recent sea-level rise has not slowed compared with the earlier satellite period. This highlights the need to quantify and correct records for short-term natural variability to extract the climate change signal.