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Meltwater pulses (MWPs) known as abrupt sea-level rise due to injection of melt water are of particular interests to scientists to investigate the interactions between climatic, oceanic and glacial systems. Eustatic sea-level rise will inevitably affect cities especially those on coastal plains of low elevation like Hong Kong. A recent study published in Quaternary Science Reviews presented evidence of abrupt sea level change between 11,300-11,000 years ago in the Arctic Ocean. The study was conducted by Ms Skye Yunshu Tian, PhD student of School of Biological Sciences and Swire Institute of Marine Science, the University of Hong Kong (HKU) during her undergraduate final year project in the Ecology & Biodiversity Major, solving the puzzle of second largest meltwater pulse (labelled as "MWP-1B" next to the largest and already well understood MWP-1A).
During the last deglaciation, melting of large ice sheets in the Northern hemisphere had contributed to profound global sea level changes. However, even the second largest MWP-1B is not well understood. Its timing and magnitude remain actively debated due to the lack of clear evidence not only from tropical areas recording near-eustatic sea-level change, but also from high-latitude areas where the ice sheets melted.
The research study, led by Ms Tian under the supervision of Dr Moriaki Yasuhara, Associate Professor of School of Biological Sciences, HKU and Dr Yuanyuan Hong, Postdoctoral Fellow of School of Biological Sciences, HKU, and in collaboration with scientists in HKU and UiT The Arctic University of Norway, discovered a robust evidence of formerly elusive abrupt sea-level jump event during the climatic warming from the last ice age to the current climate state. The study presented evidence of abrupt sea level change between 11,300-11,000 years ago of 40m-80m in Svalbard, the Arctic Ocean. High time-resolution fossil records indicate a sudden temperature rise due to the incursion of warm Atlantic waters and consequent melting of the covering ice sheets. Because of the rebound of formerly suppressed lands underneath great ice load, the sedimentary environment changed from a bathyal setting [...] to an upper-middle neritic setting [...] at the study sites. This is the first solid evidence of relative sea-level change of MWP-1B discovered in ice-proximal areas.
Journal Reference:
Skye Yunshu Tian, Moriaki Yasuhara, Yuanyuan Hong, Huai-Hsuan M. Huang, Hokuto Iwatani, Wing-Tung Ruby Chiu, Briony Mamo, Hisayo Okahashi, Tine L. Rasmussen. Deglacial–Holocene Svalbard paleoceanography and evidence of meltwater pulse 1B. Quaternary Science Reviews, 2020; 233: 106237 DOI: 10.1016/j.quascirev.2020.106237
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(Score: 2) by bzipitidoo on Thursday March 12 2020, @11:44PM
The idea that geologic change is always gradual sailed decades ago. The channeled scablands of Washington state ended that notion. However, the geologist who figured it out spent most of his career trying to convince others that it was fast. In his old age, when they were finally convinced, they showered him with awards and praise and such.
The only reasonable explanation that fit all the evidence was that the Columbia river basin was subjected to massive and rapid flooding, many times, from a glacial lake abruptly emptying. The low point in the surrounding mountains is at the northwestern corner, and the southern edge of ice age glaciers kept blocking it. So the lake would grow and grow and grow, until finally it was high enough to float the whole tip of the glacier. Then the flood was released, the tip of the glacier eroded by the rushing water, and the almost the entire lake drained. After the flood, the glacier would push back in and block it again, and the cycle would repeat. If you ever visit Missoula, Montana, look high on the sides of the surrounding mountains, and you can easily make out a bathtub ring from that lake.
I don't know which skeptics TFA is aimed at. Not geologists, no. Sounds like it's a poke at climate change deniers.