A new study reminds us that, 8200 years ago, near-global sea levels rose 6.5 meters in a span of just 140 years. This is 470 centimeters per century, 4.7 centimeters per year, during a period when CO2 levels were alleged to be a “safe” and stagnant 260 ppm.
Image Source: Nunn et al., 2024
To put this change rate in perspective, global sea levels rose at a rate of 1.56 millimeters per year from 1900 to 2018, including 1.5 mm per year rate during the more recent period from 1958-2014 (Frederikse et al., 2020, Frederikse et al., 2018). This is just under 16 centimeters per century or sixteen tenths of a centimeter (0.16 cm) per year.
Image Source: Frederikse et al., 2020 and Frederikse et al., 2018
The net melt of the Greenland ice sheet (GIS) is thought to have been the largest contributor to sea level rise in recent decades. But, to put the GIS change in context, the entire ice sheet melt contribution to sea level rise was just 1.2 total centimeters from 1992-2020 (Simonsen et al., 2021).
Image Source: Simonsen et al., 2021
The Earth’s natural range of sea level rise rates, periodically reaching 4.7 cm per year, is thus 30 times greater in magnitude than the modern period’s (1900-2018) “anthropogenic” rate, which is 0.156 cm per year.
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