| 英文摘要: | Over short periods of time, it can be difficult to isolate sea-level increase in observations as it is hidden by natural shifts in rainfall quantities over ocean and land, which cause temporary drops in the global sea-level curve. Now research shows how to detect the signal, even in short records, by estimating these variations. Over the past 20 years, satellite observations show that global sea level has been steadily increasing at a rate of 3.3 mm yr−1 (ref. 1). A continuing rise threatens to impact coastal communities through shoreline erosion, saltwater intrusion on freshwater supplies and a general increased risk of flooding2. To determine the rate of rise over short periods of time, such as the past five to ten years, we must take into account natural fluctuations such as increased rainfall over land compared with the ocean, which causes global sea level to temporarily go down3. Nevertheless, as the rain water returns to the ocean through rivers and runoff, the rate of sea-level rise will soon bounce back. As they report in Nature Climate Change, Anny Cazenave and colleagues have detected this variability by employing hydrological models that can simulate land water storage and thereby can remove this variable from the sea-level curve4.
MARK A. JOHNSON / ALAMY
The accumulation of water associated with massive floods in Australia during 2010–2011 contributed significantly to the simultaneous global mean sea-level drop.
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Affiliations
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Carmen Boening is at the Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91104, USA
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