Global sea-level budget 1993–present

Over the last 50 years more than 90 % of the excess heat excess accumulated in the climate system because of greenhouse gas emissions has been stored in the ocean. The rest has been warming the atmosphere and continents, and melting sea and land ice. Sea level rise is one of the most severe consequences of climate change from human activities, with potential major impacts on coastal societies. Determining the magnitude and importance of each component is crucial, though some are better known and easier to calculate than others. The international community, through the World Climate Research Programme’s Grand Challenge on Regional Sea Level and Coastal Impacts has recently published an extensive study assessing the various datasets used to estimate components of sea-level rise since the start of the altimetry era in 1993. These datasets are based on the combination of a broad range of space-based and in situ observations, model estimates, and algorithms. The altimetry-based global mean sea level rise averages 3.1 (± 0.3 mm) per year, with an acceleration of 0.1 mm per year over the 25-year period, according to the study. It also compared the observed global mean sea level with the sum of components. Ocean thermal expansion, glaciers, Greenland and Antarctica contribute 42 %, 21 %, 15 % and 8 % to the global mean sea level over the 1993–present period. Substantial uncertainty remains for the land water storage component, it said. The study involved scientists from around the world. Sea level rise is one of seven global climate indicators which describe the changing climate. The others are temperature, ocean heat, greenhouse gases, ocean acidity, glaciers and sea ice.