It looks like there’s a mistake in the measure of sea level rise. Getting good data is difficult; especially, when looking for data sets covering hundreds of years. Because the longest data sets are from the shores of the North Atlantic, much of the research has relied on them and applied the results around the world. Recent analyses show that the data has underpredicted the actual rise by about 10%. The oceans are rising 10% faster than we realized: adding 0.2 mm/yr to the previous 1.7 mm/yr. As arctic ice melts, it changes the local gravitational effects, and takes time to redistribute itself. That melting biased the data higher for a while, masking a steeper, more global trend. Our measurement methods continue to improve, which means the story may shift too. The concern is that the urgency may be greater than we realize.
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