英文摘要: | Internal climate variability across a range of scales is known to contribute to regional sea-level trends1, 2, 3, 4, 5, 6, 7, which can be much larger than the global mean sea-level trend in many parts of the globe. Over decadal timescales, this internal variability obscures the long-term sea-level change3, 6, 8, making it difficult to assess the effect of anthropogenic warming on sea level. Here, an attempt is made to uncover the sea-level rise pattern in the tropical Pacific Ocean associated with anthropogenic warming. More specifically, the sea-level variability associated with the Pacific Decadal Oscillation is estimated and removed from the regional sea-level trends computed from satellite altimetry measurements over the past two decades. The resulting pattern of regional sea-level rise uncovered in the tropical Pacific Ocean is explained in part by warming in the tropical Indian Ocean, which has been attributed to anthropogenic warming9. This study represents one of the first attempts at linking the sea-level trend pattern observed by satellite altimetry to anthropogenic forcing.
Addressing and mitigating the effects of changes in sea level involves accurately determining the contributing factors and associated impacts to past, present and future sea-level rise and variability. Providing such a regional assessment is a challenging task that requires expertise across a wide range of disciplines and a variety of data sources. On the basis of satellite altimetry measurements over the past two decades, regional sea-level trends can be as much as four times the rate of global mean sea level (GMSL; Fig. 1a, note the GMSL trend of ~3 mm yr−1 is removed from the figure). This severely limits the utility of any global sea-level metric for planning and adaptation purposes at the regional level. In some regions, internal climate variability on decadal timescales can lead to apparent trends that are significantly larger than the long-term trend. Identifying and explaining signals contributing to regional and global sea-level variability and trends have been frequently studied problems in recent years (for example, refs 1, 2, 3, 4, 5, 6, 7). Removing trends associated with known climate variability may allow for identification of the underlying warming trend associated with anthropogenic forcing (for example, refs 3, 6, 7, 8).
| http://www.nature.com/nclimate/journal/v4/n9/full/nclimate2307.html
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