施工実績

Exploring concerns on the dating ranging from temperature, ice volume, and you will sea level over the past 50 mil decades

Over the past years, jobs so you can imagine heat and you may sea level over the past fifty Ma have raised. During the synchronous, operate in order to model ice-sheet alter during this period have been ongoing. We remark published paleodata and modeling try to render understanding on the how sea level reacts so you’re able to switching temperature through changes in frost regularity and thermal expansion. Up until now, the temperature to help you sea level relationship might have been searched for the change out of glacial to interglacial states. Attempts to synthesize the temperature in order to sea-level dating during the deeper go out, whenever temperatures was indeed somewhat warmer than establish, was basically tentative. I first comment current temperatures and sea-level investigation and design simulations, that have a dialogue from suspicion in each of these means. We after that synthesize the ocean peak and you can temperature data and you may modeling performance i’ve analyzed to check on plausible variations towards the sea top rather than heat relationship. On this subject long timescale there are no around the world affiliate temperatures proxies, and therefore we browse the so it matchmaking using strong-ocean heat ideas and you can surface temperature info out of high and lower latitudes. It is difficult to identify between your more plausible different the warmth to sea level matchmaking given the large problems related to your proxy rates. We believe to have body large-latitude South Hemisphere temperatures and you can deep-ocean temperature, the speed away from transform from sea-level to heat has not remained lingering, i.elizabeth., linear, for the past 50 Ma, whilst the matchmaking stays unclear for the readily available lower-latitude skin temperatures studies. A great nonlinear mode anywhere between heat and you can sea-level is in line with ice-sheet acting education. That it relationship are going to be related to (1) different glacial thresholds getting Southern area Hemisphere glaciation as compared to Northern Hemisphere glaciation and you can (2) the newest ice-sheet holding ability of one’s Antarctic continent.

step 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 ].

For the past 50 billion age, eustatic sea level has ranged anywhere between ?one hundred yards above present in early Eocene (?56–44 Ma), whenever there was hardly any house freeze on the planet and you may the ocean basin frequency is lower than establish [ Miller ainsi que al., 2005a ; Kominz mais aussi al., 2008 ; Miller mais aussi al., 2009a ], and bgclive prijs you may 120–140 yards less than expose [ Fairbanks, 1989 ; Yokoyama et al., 2000 ] within the last Glacial Restriction (LGM; 19–23 ka), whenever there were higher freeze sheets during the Antarctica, America, Asia, and you can Europe [ Clark et al., 2009 ]. (Italicized terminology was laid out regarding glossary, adopting the fundamental text.) About timescale, large (more than ten m) eustatic sea level differences had been triggered predominately by the changes in the volume of belongings frost [ Miller et al., 2005a ]. Broadly, there were five ice-sheet says, such becoming (1) mainly unglaciated criteria, (2) a great glaciated East Antarctic, (3) interglacial standards with frost sheets regarding West Antarctic and you may Greenland (we.e., present-go out standards), and (4) glacial requirements towards the more growth of highest frost sheets into the the fresh new North Hemisphere [ de Boer mais aussi al., 2012 ]. The glaciation of your own East Antarctic can then broken into an advanced state with ephemeral slope freeze caps and you can a completely glaciated county [ ].