[{"command":"openDialog","selector":"#drupal-modal","settings":null,"data":"\u003Cdiv id=\u0022republish_modal_form\u0022\u003E\u003Cform class=\u0022modal-form-example-modal-form ecl-form\u0022 data-drupal-selector=\u0022modal-form-example-modal-form\u0022 action=\u0022\/en\/article\/modal\/7405\u0022 method=\u0022post\u0022 id=\u0022modal-form-example-modal-form\u0022 accept-charset=\u0022UTF-8\u0022\u003E\u003Cp\u003EHorizon articles can be republished for free under the Creative Commons Attribution 4.0 International (CC BY 4.0) licence.\u003C\/p\u003E\n \u003Cp\u003EYou must give appropriate credit. We ask you to do this by:\u003Cbr \/\u003E\n 1) Using the original journalist\u0027s byline\u003Cbr \/\u003E\n 2) Linking back to our original story\u003Cbr \/\u003E\n 3) Using the following text in the footer: This article was originally published in \u003Ca href=\u0027#\u0027\u003EHorizon, the EU Research and Innovation magazine\u003C\/a\u003E\u003C\/p\u003E\n \u003Cp\u003ESee our full republication guidelines \u003Ca href=\u0027\/horizon-magazine\/republish-our-stories\u0027\u003Ehere\u003C\/a\u003E\u003C\/p\u003E\n \u003Cp\u003EHTML for this article, including the attribution and page view counter, is below:\u003C\/p\u003E\u003Cdiv class=\u0022js-form-item form-item js-form-type-textarea form-item-body-content js-form-item-body-content ecl-form-group ecl-form-group--text-area form-no-label ecl-u-mv-m\u0022\u003E\n \n\u003Cdiv\u003E\n \u003Ctextarea data-drupal-selector=\u0022edit-body-content\u0022 aria-describedby=\u0022edit-body-content--description\u0022 id=\u0022edit-body-content\u0022 name=\u0022body_content\u0022 rows=\u00225\u0022 cols=\u002260\u0022 class=\u0022form-textarea ecl-text-area\u0022\u003E\u003Ch2\u003E\u2018Impossible to adapt\u2019: Surprisingly fast ice-melts in past raise fears about sea level rise\u003C\/h2\u003E\u003Cp\u003EAt one point in a comparable period they were rising at three metres per century, or 30mm a year, according to Dr Fiona Hibbert, a geologist at York University in the UK. The current rate of rise is \u003Ca href=\u0022https:\/\/oceanservice.noaa.gov\/facts\/sealevel.html\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003E3.2mm\u003C\/a\u003E per year.\u003C\/p\u003E\u003Cp\u003EDr Hibbert is working on a project called \u003Ca href=\u0022https:\/\/cordis.europa.eu\/project\/id\/838841\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003EExTaSea\u003C\/a\u003E, which predicts worst-case scenarios for sea level rise around the globe. The goal is to help policymakers take long-term decisions, for example about the siting of enduring infrastructure such as nuclear power stations.\u003C\/p\u003E\u003Cp\u003EDevising models that can make such predictions is notoriously difficult, she says.\u003C\/p\u003E\u003Cp\u003E\u2018We\u2019re not entirely sure of all the processes involved. When you melt an ice sheet sometimes it\u2019s really long-time scales that they operate over, which is quite difficult to put into a model.\u2019\u003C\/p\u003E\u003Cp\u003EAnd melting itself alters the system \u2013 for example, by lightening the load on the Earth\u2019s crust which then undergoes a slow-motion rebound over thousands of years.\u003C\/p\u003E\u003Cp\u003EA further issue is that data on recent sea levels dates back only 150 years \u2013 for tide gauges \u2013 and just 20-25 years for satellite measurements.\u0026nbsp;\u003C\/p\u003E\u003Cp\u003EBecause of this, geologists such as Dr Hibbert, and Professor Alessio Rovere, a geoscientist at the University of Bremen in Germany, are looking back to see what happened during the last interglacial period.\u003C\/p\u003E\u003Cp\u003E\u2018The geological record is great because it includes all the processes,\u2019 said Dr Hibbert.\u003C\/p\u003E\u003Cp\u003E\u003Cblockquote class=\u0022tw-text-center tw-text-blue tw-font-bold tw-text-2xl lg:tw-w-1\/2 tw-border-2 tw-border-blue tw-p-12 tw-my-8 lg:tw-m-12 lg:tw--ml-16 tw-float-left\u0022\u003E\n \u003Cspan class=\u0022tw-text-5xl tw-rotate-180\u0022\u003E\u201c\u003C\/span\u003E\n \u003Cp class=\u0022tw-font-serif tw-italic\u0022\u003E\u2018When you melt an ice sheet sometimes it\u2019s really long-time scales that they operate over, which is quite difficult to put into a model.\u2019\u003C\/p\u003E\n \u003Cfooter\u003E\n \u003Ccite class=\u0022tw-not-italic tw-font-normal tw-text-sm tw-text-black\u0022\u003EDr Fiona Hibbert, York University, UK\u003C\/cite\u003E\n \u003C\/footer\u003E\n\u003C\/blockquote\u003E\n\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EInterglacial\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003EWe live in an interglacial period known as the Holocene. \u2018For the last 6,000 years, humans have enjoyed rather stable climate and sea level conditions, and prospered thanks to this,\u2019 said Prof. Rovere.\u003C\/p\u003E\u003Cp\u003EThe closest analogue to the Holocene in the geological past is the last interglacial, which occurred between 125,000 and 118,000 years ago. During this time, the global temperature was about one to two degrees higher than the baseline pre-industrial temperatures used to measure climate change today, due to slight differences in the Earth\u2019s tilt and orbit.\u0026nbsp;\u003C\/p\u003E\u003Cp\u003EGeologists can find clues to the sea level at this time from fossilised coral reefs that were stranded as cliff layers when seas subsided, as well as the chemical composition of tiny, marine organisms known as foraminifera, which give an idea of the reach of the sea in the past, says Dr Hibbert.\u003C\/p\u003E\u003Cp\u003EAnd Prof. Rovere, who runs a project called \u003Ca href=\u0022https:\/\/cordis.europa.eu\/project\/id\/802414\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003EWARMCOASTS\u003C\/a\u003E, also considers what ancient beaches \u2013 which also became layers in the cliffs \u2013 can tell us.\u003C\/p\u003E\u003Cp\u003E\u2018A beach today has sands forming along the shoreline \u2026 imagine that all of this \u2026 can be frozen in time because it becomes rock. So we can go back, and look at rocks that were former beaches,\u2019 he said. From their characteristics and the shells preserved inside them, \u2018we can make connections to the changing sea level\u2019, he said.\u003C\/p\u003E\u003Cp\u003ETeasing out the right message from stranded reefs and beaches is tricky, however. A receding sea might leave remnants of its presence in one place, only for them to be uplifted \u2013 or dropped \u2013 by subsequent geological activity.\u003C\/p\u003E\u003Cp\u003EProf. Rovere experienced these problems when trying to solve the enduring puzzle of mysterious, huge boulders which lie atop 15-metre cliffs on the island of Eleuthera in The Bahamas. While some in the field believe they were flung there by super-storms, others, including him, think a combination of higher sea levels plus lesser storms were responsible.\u003C\/p\u003E\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u003Cem\u003E\u003Cstrong\u003EListen: Prof. Rovere describes how boulders may have ended up on top of cliffs in The Bahamas.\u003C\/strong\u003E\u003C\/em\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003E\u0026nbsp;\u003Caudio src=\u0022\/sites\/default\/files\/hm\/IMCEUpload\/sea-level-rovere_0.mp3\u0022 controls=\u0022controls\u0022\u003E\u003C\/audio\u003E\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003ETen times higher\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003EDespite these challenges, Dr Hibbert amalgamated ancient coral reef analyses done by scientists around the globe and concluded that sea levels rose at \u2018really high\u2019 rates \u2013 of \u003Ca href=\u0022https:\/\/www.nature.com\/articles\/s41467-019-12874-3\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003Eup to three metres per century\u003C\/a\u003E, \u2018which is about ten times higher than current rates.\u2019\u003C\/p\u003E\u003Cp\u003EProf. Rovere is gathering data on geological features such as ancient corals and beaches to create a database that will help give a nuanced story of how sea levels changed in different places and the strength of the waves during the last interglacial.\u003C\/p\u003E\u003Cp\u003EIt\u2019s hard interpreting geological data, so Prof. Rovere is also drawing on models more commonly used by engineers to understand the impact of waves and currents on harbours \u2013 they can help him understand how sand was deposited along interglacial shores.\u003C\/p\u003E\u003Cp\u003E\u2018By combining these two different disciplines \u2026 we can say much more about the past than we can do with just the geological interpretation of the rocks,\u2019 he said.\u003C\/p\u003E\u003Cp\u003EHis work is producing slightly different figures.\u003C\/p\u003E\u003Cp\u003E\u2018In some rock records \u2013 there are some characteristics that make us think that at some point during this warm period the sea level jumped, from three metres to six metres,\u2019 he said. This equates to about 10 mm a year. The jump occurred in a relatively short time, he says.\u003C\/p\u003E\u003Cp\u003E\u2018This is really interesting because today we are in a warm period \u2013 naturally as well as because of climate change \u2013 and in the last interglacial, even without us giving warmth to the system, some data suggest that there was this jump.\u003C\/p\u003E\u003Cp\u003E\u2018Now this is a very debated idea but what if it is true? It means there is this possibility of rapid melting of ice, on top of what we do as humans.\u2019\u003C\/p\u003E\u003Cp\u003EProf. Rovere says that a 10mm a year sea level rise would be \u2018almost impossible\u2019 to adapt to with sufficient speed. \u2018It means we just have to abandon our cities,\u2019 he added.\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EAcceleration\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003EThe prospect of a sudden acceleration in ice melting is further supported by work done by Dr Yucheng Lin, a student of Dr Hibbert\u2019s as part of the ExTaSea project.\u003C\/p\u003E\u003Cp\u003EThis time the reference period is 24,000 to 11,000 years ago, Earth\u2019s most recent deglaciation, which preceded the Holocene.\u003C\/p\u003E\u003Cp\u003EThis period was substantially different from today which makes it \u2018not so great for looking at the future,\u2019 said Dr Hibbert. For example, there were huge ice sheets over North America and Europe.\u003C\/p\u003E\u003Cp\u003EBut they found that, at the peak of the ice-melt, seas rose at \u003Ca href=\u0022https:\/\/www.nature.com\/articles\/s41467-021-21990-y\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003E3.6 metres per century\u003C\/a\u003E.\u003C\/p\u003E\u003Cp\u003E\u2018Again, these are really high numbers, so ice sheets can lose mass really quite quickly,\u2019 said Dr Hibbert.\u003C\/p\u003E\u003Cp\u003EShe is now considering how such a rapid melting would play out this century on different coasts.\u003C\/p\u003E\u003Cp\u003E\u003Cem\u003E\u003Cstrong\u003EJust how are our seas changing and rising with climate change and the melting of Earth\u2019s ice caps? In this three-part series, we look at\u0026nbsp;the past, present and future of extreme sea level rise. Coming next, in part two we will look at rise of atmospheric \u2018meteotsunamis\u2019.\u003C\/strong\u003E\u003C\/em\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cem\u003EThe research in this article was funded by the EU. 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