Examining concerns from the dating anywhere between temperatures, ice frequency, and sea-level over the past fifty mil many years
For the past decade, work in order to imagine temperature and you can sea-level for the past fifty Ma have raised. Into the parallel, operate to help you model ice sheet changes during this time had been constant. I remark had written paleodata and you may acting work to promote insights towards exactly how sea-level reacts to switching heat due to alterations in ice frequency and you may thermal expansion. Up to now, heat to sea level relationship has been explored into the changeover regarding glacial so you can interglacial states. Tries to synthesize the heat so you’re able to sea level dating inside the greater date, whenever temperatures were rather more comfortable than just establish, was in fact tentative. I first comment current temperatures and you can sea-level research and you can model simulations, which have a discussion away from uncertainty into the each of these approaches. I after that synthesize the ocean top and you may heat analysis and you can acting show i have analyzed to check possible versions for the water height in place of heat dating. On this long timescale there aren’t any around the globe associate temperature proxies, thereby i take a look at it matchmaking playing with strong-ocean temperature suggestions and you can epidermis temperatures facts regarding highest and you can reduced latitudes. It is hard to recognize between your additional probable forms of heat so you can sea level relationship because of the wider errors relevant into the proxy prices. We believe having epidermis higher-latitude Southern area Hemisphere temperatures and you may strong-ocean heat, the pace from alter away from sea level so you can heat has not remained constant, we.e., linear, for the past 50 Ma, whilst the matchmaking stays unknown into readily available lower-latitude surface temperatures data. A great nonlinear function between temperatures and you can sea-level are consistent with ice sheet acting studies. This matchmaking will be attributed to (1) different glacial thresholds to own Southern area Hemisphere glaciation than the Northern Hemisphere glaciation and (2) the latest ice-sheet holding potential of Antarctic continent.
step one. 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 ].
For the past fifty million ages, eustatic sea level provides varied between ?one hundred yards above found in the first Eocene (?56–44 Ma), when there is almost no property frost on the planet and you can the sea basin regularity is less than introduce [ Miller mais aussi al., 2005a ; Kominz ainsi que al., 2008 ; Miller ainsi que al., 2009a ], and you may 120–140 meters less than introduce [ Fairbanks, 1989 ; Yokoyama ainsi que al., 2000 ] over the last Glacial Limitation (LGM; 19–23 ka), whenever there have been large ice sheet sets from inside the Antarctica, The united states, Asia, and you will Europe [ Clark mais aussi al., 2009 ]. (Italicized terms and conditions is discussed on the glossary, adopting the fundamental text.) On this timescale, higher (higher than ten meters) eustatic sea level variations were brought about mainly of the changes in the quantity off land frost [ Miller mais aussi al., 2005a ]. Broadly, there have been five ice sheet states, this type of are (1) mainly unglaciated standards, (2) good glaciated Eastern Antarctic, (3) interglacial standards with increased freeze sheet sets on West Antarctic and Greenland (we.elizabeth., present-go out requirements), and you will (4) glacial requirements for the more development of highest frost sheet sets into the the new Northern Hemisphere [ de- Boer ainsi que al., 2012 ]. The fresh new glaciation of the Eastern Antarctic can be then broken down into an chat zozo aanmelden intermediate condition having ephemeral slope freeze limits and you may a completely glaciated condition [ ].