New Paper: Sea Levels Higher 4000 Years Ago With Reefs Adapting. By P Gosselin on 28. October 2020 A new in-press journal pre-proof paper by Hallmann et al examines reef response to sea-level and environmental changes in the Central South Pacific over the past 6000 years. Hat-tip: Reader Mary Brown The paper documents that sea levels globally saw a single short-lived sea-level highstand between 4100 and 3400 yr before present and coral reefs adapt to changes.
A pristine reef in American Samoa, Credits: NOAA/NMFS/PIFSC/CRED, Oceanography Team, public domain Abstract Geological records of coastal system evolution during past higher and/or rising sea levels provide an important baseline for developing projections regarding the response of modern coastal systems to future sea-level rise. This paper documents in unprecedented detail the response of coral reefs and coastal systems to changing accommodation space in relation to mid-late Holocene sea-level changes in French Polynesia. 4 New Papers Suggest Falling Sea Levels More Harmful To Corals Than Rapidly Rising Sea Levels. By Kenneth Richard on 16. March 2017 Are Modern Rates Of Sea Level Rise Too Slow For Optimal Coral Growth? Since the 20th century began, global sea levels have been rising at rates of about 1.7 – 1.8 mm/year, or about 0.17 to 0.18 of a meter (~7 inches) per century.
Zerbini et al., 2017 “Our estimated rates for the northern Mediterranean, a relatively small regional sea, are slightly lower than the global mean rate, + 1.7 ± 0.2 mm/year, recently published in the IPCC AR5 (Intergovernmental Panel on Climate Change 5th Assessment Report) … Our regional results, however, are in close agreement with the global mean rate, + 1.2 mm/year, published by Hay et al. (2015) which is currently being discussed by the oceanographic community.” Svendsen et al., 2016 “From our reconstruction, we found that the Arctic mean sea level trend is around 1.5 mm +/- 0.3 mm/y for the period 1950 to 2010, between 68ºN and 82ºN. Parekh et al., 2017 McAneney et al., 2017 Wenzel and Schröter, 2014 Eghbert et al., 2017. Study: Coral Reef Islands Grow with Rising Sea Level.
Another study confirming that coral reef islands are dynamic, and adjust rapidly to changes in sea level. Coral reef islands can accrete vertically in response to sea level riseGerd Masselink, Eddie Beetham and Paul KenchVol. 6, no. 24, eaay3656DOI: 10.1126/sciadv.aay3656 AbstractIncreased flooding due to sea level rise (SLR) is expected to render reef islands, defined as sandy or gravel islands on top of coral reef platforms, uninhabitable within decades. Such projections generally assume that reef islands are geologically inert landforms unable to adjust morphologically. We present numerical modeling results that show reef islands composed of gravel material are morphodynamically resilient landforms that evolve under SLR by accreting to maintain positive freeboard while retreating lagoonward.
Such island adjustment is driven by wave overtopping processes transferring sediment from the beachface to the island surface. Coral mortality induced by the 2015–2016 El-Niño in Indonesia: the effect of rapid sea level fall. Floating Islands | Watts Up With That? Guest Post by Willis Eschenbach Much has been written of late regarding the impending projected demise of the world’s coral atoll islands due to CO2-caused sea level rise. Micronesia is suing the Czech Government over CO2 emissions that they claim are damaging their coral atolls via sea level rise. Tuvalu and the Maldives are also repeating their claims of damage from CO2. If the sea level rises much, they say they will simply be swept away. Recently, here in the Solomon Islands, the sea level rise has been blamed for salt water intrusion into the subsurface “lens” of fresh water that forms under atolls. Beneath the surface of most atolls, there is a lens shaped body of fresh water.
In this paper, I will discuss the three inter-related claims that people are making as illustrated above. 1. 2. 3. I will look at the real causes of the very real problems faced by atoll dwellers. And before you ask, how do I know this atoll stuff? Claim 1. Short answer, data to date says no. Figure 1. 3. 1. Falling Sea Level: The Critical Factor in 2016 Great Barrier Reef Bleaching! | Watts Up With That? Guest essay by Jim Steele Director emeritus Sierra Nevada Field Campus, San Francisco State University and author of Landscapes & Cycles: An Environmentalist’s Journey to Climate Skepticism It is puzzling why the recent 2017 publication in Nature, Global Warming And Recurrent Mass Bleaching Of Corals by Hughes et al. ignored the most critical factor affecting the 2016 severe bleaching along the northern Great Barrier Reef – the regional fall in sea level amplified by El Niño.
Instead Hughes 2017 suggested the extensive bleaching was due to increased water temperatures induced by CO2 warming. In contrast in Coral Mortality Induced by the 2015–2016 El-Niño in Indonesia: The Effect Of Rapid Sea Level Fall by Ampou 2017, Indonesian biologists had reported that a drop in sea level had bleached the upper 15 cm of the reefs before temperatures had reached NOAA’ Coral Reef Watch’s bleaching thresholds. Hughes reported the various proportions of areal bleaching as degrees of severity. I wept. Rising Sea Levels May Build, Rather Than Destroy, Coral Reef Islands - The Global Warming Policy Forum (GWPF)The Global Warming Policy Forum. Rising global sea levels may actually be beneficial to the long-term future of coral reef islands, such as the Maldives, according to new research published in Geophysical Research Letters.
Rising global sea levels may actually be beneficial to the long-term future of coral reef islands, such as the Maldives, according to new research published in Geophysical Research Letters. Low-lying coral reef islands are typically less than three metres above sea level, making them highly vulnerable to rising sea levels associated with climate change. However, research has found new evidence that the Maldives – the world’s lowest country – formed when sea levels were higher than they are today.
The evidence was discovered by researchers who studied the formation of five islands in the southern Maldives. Using a coring technique, they were able to reconstruct how and when the islands formed. At the time, sea levels were up to 0.5 metres higher than they are today, which gave the waves more energy.