Sea Level

Number of papers: 8

Reconciling past changes in Earth’s rotation with 20th century global sea-level rise: Resolving Munk’s enigma — Science Advances, 2015; Mitrovica et al.

Changes to the earth’s rotation speed by tiny amounts explains observed sea-level rise and allows more accurate projections for the future. Nothing to do with CO2.

Late Quaternary meltwater pulses and sea level change — Journal of Quaternary Science, 2018; Harrison et al.

This paper surveys a number of sites around the world that serve as proxies for sea-level. It is, in effect, a meta-analysis of other studies and data. They document the sea-level rise since the last glacial maximum 20k years ago. We know from tide-gauge data for the past 200 years, sea-level has been rising at a fairly steady rate of 1mm/year. In their analysis, they find some melt-water events in the last 20k years that forced sea-level rise of greater than 45 mm per year. They show three periods of rapid sea-level rise: 1) 19.5–18.8k years ago produced a 10mm rise annually, 2) 14.8–13k years ago produced a rise of 20mm per year and may have reached 40mm per year at times, and 3) 11.5–11.1k years ago produced rises of more than 40mm per year. They calculate that meltwater pulses account for 35–52 m of total sea-level rise. Therefore, natural meltwater pulses can force sea level to rise very quickly. The authors add “The scientific consensus view by IPCC (Church et al., 2013) is that AGW and increasing GMSL rise could increase the rate of ice recession from Greenland and Antarctica, but it is highly unlikely that MWPs on the scale of those that occurred after the LGM would occur in the foreseeable future. Even if they did their impact on the long-term sea level rise it would probably be modest.”

Redating the earliest evidence of the mid-Holocene relative sea-level highstand in Australia and implications for global sea-level rise — Plos One, 2019; Dougherty et al.

“In northeast Australia (Queensland) it is currently accepted that a highstand of 1 to 1.5 m above present mean sea level was reached around 7,000 years ago. Conversely, in southeast Australia, early research suggested that sea-level reached present-day elevations 7,000 years ago and maintained PMSL through the mid- to late- Holocene. Subsequent work from Bulli Beach, a site ~80 km south of Sydney, however, has provided evidence for an early Holocene sea-level highstand of +1.84 m possibly dating back as early as 8,000 years ago.” The authors revisited the Bulli beach data, took new measurements, and conclude that the highstand probably occurred about 1,000 years later than originally thought. This confirms that sea levels were naturally at least 1 meter higher than today making the word “unprecedented” inaccurate in IPCC literature.

A 180-Million-Year Record of Sea Level and Ice Volume Variations from Continental Margin and Deep-Sea Isotopic Records — Oceanography, 2011; Miller et al.

“A global sea level rise of 120 m followed the last glacial maximum, with rates that exceeded 10 times the modern rate of rise (> 40 mm yr-1 versus ~ 3 mm yr-1).”

The causes of sea-level rise since 1900 — Nature, 2020; Frederickse et al.

The authors conclude “Our results reconcile the magnitude of observed global-mean sea-level rise since 1900 with estimates based on the underlying processes, implying that no additional processes are required to explain the observed changes in sea level since 1900.” In other words, there is no “hand of man” signature anywhere in the sea-level record.

Global-scale changes in the area of atoll islands during the 21st century — Anthropocene, 2021; Holdaway et al.

This paper starts with the obligatory “The long-term persistence of atoll islands is under threat due to continued sea level rise driven by anthropogenic climate change.” and a few sentences later: “Results show that, between 2000 and 2017, the total land area on these atolls has increased by 61.74 km2 (6.1 %) from 1007.60 km2 to 1069.35 km2. Since 2000, the Maldives have added 37.50 km2 of land …” They continue: “Despite the widely circulated assertion that atoll islands are actively eroding, however, little scientific evidence exists to support such blanket claims. Records do not exist of widespread, chronic erosion of atoll islands under current rates of sea level rise (Duvat, 2019). Rather, studies have shown that islands have persisted, and in many cases increased in size, since the mid-20th century (Kench et al., 2018; Duvat, 2019).”

Patterns of island change and persistence offer alternate adaptation pathways for atoll nations — Nature Communications, 2018; Kench et al.

“Using remotely sensed data, change is analysed over the past four decades, a period when local sea level has risen at twice the global average (~3.90 ± 0.4 mm.yr−1). Results highlight a net increase in land area in Tuvalu of 73.5 ha (2.9%), despite sea-level rise, and land area increase in eight of nine atolls. Island change has lacked uniformity with 74% increasing and 27% decreasing in size. Results challenge perceptions of island loss, showing islands are dynamic features that will persist as sites for habitation over the next century …”

A revised acceleration rate from the altimetry-derived global mean sea level record — Nature Scientific Reports, 2019; Kleinherenbrink et al.

A few data scientists finally show that the “dramatic acceleration in sea-level rise” they had been feeding the media is actually just multi-satellite instrument calibration error, as many of us have known for years. From the abstract: “We provide a new and more accurate estimate of the intra-mission bias, which leads to a much reduced GMSL acceleration over the whole record.”