Investigating concerns on the matchmaking anywhere between temperature, ice regularity, and you can sea-level for the past 50 billion many years
Over the past years, efforts in order to guess heat and sea level for the past 50 Ma have raised. From inside the synchronous, services so you can design ice-sheet alter during this period had been lingering. I remark wrote paleodata and modeling strive to bring facts into just how sea level responds to help you altering heat using changes in frost regularity and you will thermal expansion. Thus far, the temperature so you’re able to sea level relationship could have been explored towards change of glacial in order to interglacial says. Attempts to synthesize heat to help you sea level relationships in the higher date, whenever temperatures have been notably warmer than simply introduce, were tentative. I earliest comment the current temperatures and you will sea level analysis and you can design simulations, having a dialogue out of suspicion inside the every one of these techniques. We upcoming synthesize the sea height and you can temperatures investigation and modeling show we have examined to check plausible models for the sea peak in place of temperatures relationships. With this very long timescale there are no worldwide associate temperature proxies, and thus i check out the so it relationship having fun with deep-water temperatures information and facial skin temperatures suggestions from higher and you may reduced latitudes. It is difficult to distinguish involving the more possible kinds of the temperature in order to sea level matchmaking considering the wider problems related towards the proxy estimates. We believe to have body high-latitude Southern Hemisphere heat and you will deep-ocean temperatures, the speed from alter away from sea level in order to temperatures have not remained ongoing, i.elizabeth., linear, over the past fifty Ma, even though the dating stays ambiguous for the available reduced-latitude skin temperature data. A nonlinear mode anywhere between temperatures and you may sea-level is in line with ice-sheet acting degree. It matchmaking can be caused by (1) various glacial thresholds to possess Southern Hemisphere glaciation versus North Hemisphere glaciation and you may (2) the newest ice-sheet holding skill of one’s Antarctic region.
1. Inclusion
Understanding and predicting glacier and ice sheet dynamics is notoriously difficult [ Alley et al., 2005 ; Allison et al., 2009 ], and as a result, in their fourth assessment report the Intergovernmental Panel on Climate Change did not provide sea level projections that accounted for rapid dynamical changes in ice flow [ Solomon et al., 2007 ]. The observational record contains worrying examples of nonlinear threshold type responses, such as the collapse of the Larsen B ice shelf and subsequent surging of glaciers [ De Angelis and Skvarca, 2003 ; Rignot et al., 2004 ]. However, the observational record does not help us constrain large changes to the ice sheets. Although there is no known analog to projected future warming in the paleoclimate record [ Crowley, 1990 ; Haywood et al., 2011 ], it does contain examples of large-scale changes to the ice sheets [ a ]. The paleoclimate record can therefore aid understanding of ice sheet behavior and provide insight into the plausibility of large ice sheet changes in a warming world [ Scherer et al., 1998 ; Pollard and ]. By looking to the paleoclimate record we can also attempt to better understand the relationship between different climate parameters, such as temperature, atmospheric CO2, ice volume, 
and sea level [ Rohling et al., 2009 ].
Over the past 50 million many years, eustatic sea-level keeps ranged between ?a hundred meters over within early Eocene (?56–49 Ma), whenever there was little belongings ice in the world and you will the ocean basin regularity try lower than present [ Miller mais aussi al., 2005a ; Kominz mais aussi al., 2008 ; Miller et al., 2009a ], and 120–140 meters lower than present [ Fairbanks, 1989 ; Yokoyama et al., 2000 ] over the last Glacial Limit (LGM; 19–23 ka), when there were higher ice sheets inside the Antarctica, The united states, China, and you will Europe [ Clark ainsi que al., 2009 ]. (Italicized terminology was outlined in the glossary, following the chief text.) About timescale, higher (more than 10 meters) eustatic sea level variations have been caused predominately of the changes in the volume off house freeze [ Miller mais aussi al., 2005a ]. Broadly, there had been four ice sheet says, such being (1) largely unglaciated criteria, (2) good glaciated Eastern Antarctic, (3) interglacial conditions with more ice sheet sets in the Western Antarctic and you may Greenland (we.age., present-go out criteria), and you can (4) glacial requirements on the more growth of higher frost sheets within the the newest Northern Hemisphere [ de Boer et al., 2012 ]. The newest glaciation of your East Antarctic can be subsequent broken on to an intermediate condition having ephemeral slope frost caps and you may a totally glaciated county [ ].