New PNAS Study: Rate Of Sea Level Rise Has Nearly Tripled Since 1990

[hatrack]

Oops.

A new scientific analysis finds that the Earth’s oceans are rising nearly three times as rapidly as they were throughout most of the 20th century, one of the strongest indications yet that a much feared trend of not just sea level rise, but its acceleration, is now underway. “We have a much stronger acceleration in sea level rise than formerly thought,” said Sönke Dangendorf, a researcher with the University of Siegen in Germany who led the study along with scientists at institutions in Spain, France, Norway and the Netherlands.

Their paper, just out in the Proceedings of the National Academy of Sciences, isn’t the first to find that the rate of rising seas is itself increasing — but it finds a bigger rate of increase than in past studies. The new paper concludes that before 1990, oceans were rising at about 1.1 millimeters per year, or just 0.43 inches per decade. From 1993 through 2012, though, it finds that they rose at 3.1 millimeters per year, or 1.22 inches per decade.

The cause, said Dangendorf, is that sea level rise throughout much of the 20th century was driven by the melting of land-based glaciers and the expansion of seawater as it warms, but sea level rise in the 21st century has now, on top of that, added in major contributions from the ice sheets of Greenland and Antarctica. “The sea level rise is now three times as fast as before 1990,” Dangendorf said.

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Kopp added that in the past five years, there is some indication that sea level rise could already be even higher than the 3.1 millimeter annual rate seen from 1993 through 2012. He cautioned, though, that “those higher rates over a short period of time probably include some level of natural variability as well as continued, human-caused acceleration.” Just how much control we are able to exert over the rate of sea level rise will critically depend on how rapidly global greenhouse gas emissions come down in coming years — making the entire outlook closely tied to whether the United States sticks with the rest of the world in honoring the Paris climate agreement.

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https://www.washingtonpost.com/news/energy-environment/wp/2017/05/22/scientists-say-the-rate-of-sea-level-rise-has-nearly-tripled-since-1990/?utm_term=.f38c98490cb8

[OKIsItJustMe]

1. IPCC WGI AR5 Chapters 3, 13; Sections 6.3.1-3, 6.3.5 says not a problem

Last edited Tue May 23, 2017, 12:35 PM - Edit history (1)

http://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_Chapter13_FINAL.pdf

… We have considered the evidence for higher projections and have concluded that there is currently insufficient evidence to evaluate the probability of specific levels above the assessed likely range. Based on current understanding, only the collapse of marine-based sectors of the Antarctic ice sheet, if initiated, could cause global mean sea level to rise substantially above the likely range during the 21st century. This potential additional contribution cannot be precisely quantified but there is medium confidence that it would not exceed several tenths of a meter of sea level rise during the 21st century. {13.5.1, Table 13.5, Figures 13.10, 13.11}

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Since they didn’t know how to calculate it, they just left it out…

[OKIsItJustMe]

2. Reassessment of 20th century global mean sea level rise

http://www.pnas.org/cgi/doi/10.1073/pnas.1616007114