Over the past 10 years, efforts to estimate temperatures and sea level for the past 50 Ma have raised. During the synchronous, services so you can model ice sheet change during this time was indeed ongoing. I opinion had written paleodata and you can modeling work to promote skills toward exactly how sea level reacts in order to switching temperature due to alterations in ice frequency and you will thermal expansion. Thus far, the temperature so you’re able to sea-level matchmaking has been searched with the changeover regarding glacial to interglacial claims. Attempts to synthesize the warmth in order to sea level dating inside greater big date, when heat were significantly hotter than expose, was indeed tentative. I earliest remark the current temperatures and you may sea-level analysis and you may model simulations, that have a dialogue out-of suspicion from inside the every one of these chatspin zoeken steps. I upcoming synthesize the sea peak and you can temperatures analysis and modeling overall performance we have reviewed to check probable models on ocean peak rather than temperatures relationship. About this long timescale there are not any global representative heat proxies, and thus we take a look at the it matchmaking playing with deep-ocean temperature records and you will skin temperature ideas out of high and you will low latitudes. It is hard to identify amongst the additional probable different the warmth to help you sea level relationship given the wider mistakes related toward proxy rates. I argue that to own skin highest-latitude Southern Hemisphere temperature and you will strong-ocean heat, the rate out-of changes from sea level so you’re able to temperatures has not stayed lingering, we.e., linear, for the past 50 Ma, as the matchmaking remains not clear toward offered low-latitude surface heat investigation. An effective nonlinear setting between temperatures and you may sea level is actually in line with ice-sheet modeling knowledge. Which relationships will be associated with (1) various glacial thresholds having South Hemisphere glaciation versus Northern Hemisphere glaciation and you may (2) the new ice-sheet carrying skill of the Antarctic continent.
step 1. Introduction
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 mil years, eustatic sea-level have ranged between ?one hundred m a lot more than within the early Eocene (?56–44 Ma), whenever there’s hardly any home freeze on earth and you can the ocean basin volume try less than establish [ Miller ainsi que al., 2005a ; Kominz et al., 2008 ; Miller et al., 2009a ], and 120–140 yards lower than introduce [ Fairbanks, 1989 ; Yokoyama ainsi que al., 2000 ] over the last Glacial Restrict (LGM; 19–23 ka), whenever there are high freeze sheet sets inside the Antarctica, United states, Asia, and you can European countries [ Clark mais aussi al., 2009 ]. (Italicized conditions try outlined about glossary, after the head text.) On this subject timescale, highest (more than ten yards) eustatic sea-level distinctions have been triggered predominately by alterations in the amount of homes freeze [ Miller mais aussi al., 2005a ]. Broadly, there have been five ice-sheet claims, such becoming (1) mostly unglaciated standards, (2) a great glaciated East Antarctic, (3) interglacial standards with ice sheets from the West Antarctic and Greenland (i.age., present-go out conditions), and you can (4) glacial conditions to the most growth of highest ice sheet sets when you look at the the Northern Hemisphere [ de Boer ainsi que al., 2012 ]. Brand new glaciation of your own East Antarctic is also further broken on to an advanced condition with ephemeral mountain freeze hats and a fully glaciated state [ ].