By Kenneth Richard on 11. January 2021
A new analysis of global sea level rise rates concludes the rising trend was 1.56 mm/yr−¹ from 1900-2018. This is the same rate as for 1958-2014 (1.5 mm/yr−¹), indicating there has not been a long-term distinctive change in sea level rise rates in the last 120 years.
In 2018, Frederikse et al. assessed the contributing factors to long-term sea level rise from 1958 to 2014. They determined ice melt and thermal expansion combined to add 1.3 mm/yr−¹ to sea levels during this period, and the overall rate of sea level rise was 1.5 mm/yr−¹.
Image Source: Frederikse et al., 2018
Then, in a study published last August, Frederikse et al. (2020) assessed global sea level rise rates and its sum of contributors since 1900. Interestingly, they found the rates of sea level rise were effectively the same for the entire 1900 to 2018 period (1.56 mm/yr−¹) as they were from 1958-2014 (1.5 mm/yr−¹).
The overall long-term trend in sea level rise has undergone an oscillation: high rates in the 1930s and 1940s, a slowdown during the 1960s and 1970s, and then a return to high rates in recent decades.
It’s interesting to note that the ice melt contribution to sea level rise – including the ice melt contribution from the Greenland ice sheet – was higher in the 1930s and 1940s than it has been during the last few decades. In fact, the contribution from total ice mass loss from glaciers was higher for the entire 1900-2018 period (0.70 mm/yr−¹) than it has been since 1957 (0.52 mm/yr−¹), suggesting a relative slowdown.
Neither of these trends – the multi-decadal oscillation in rates or higher ice mass contribution prior to 1950 – would appear to correlate well with the linearly accelerated rise in CO2 emissions since the 1940s.