Sea surface temperature (SST) proxies suggest that during the Eocene, the high latitudes were significantly warmer than present, approaching or even exceeding temperatures seen in the modern tropics [ Bijl et al., dos009 ; Hollis et al., 2009 ; Liu et al., 2009 ; Bijl et al., 2010 ]. , 2006 ; Lear et al., 2008 ; Keating-Bitonti et al., 2011 ], suggesting that there was a much reduced latitudinal temperature gradient [ Huber, 2008 ; Bijl et al., 2009 ]. During glacial conditions, the surface high latitudes show cooling [ Jouzel et al., 2007 ], with this cooling also extending to low latitudes, suggesting that there were additional feedbacks on the climate system, such as CO₂ feedbacks, in addition to orbital driven forcing [ Herbert et al., 2010 ; Rohling et al., 2012 ].

Over the past 50 Ma here have also been significant tectonic alter, for instance the uplift of your own Himalayas adopting the collision off Asia that have Asia, the opening of your Drake and you may Tasman verses, additionally the closure of one’s Panama seaway, with most of the had an influence on the fresh new environment system [ Zachos ainsi que al., 2001 ].

1.1. Temperatures to Sea-level Relationships

Surface temperature is associated with sea level and their handle for the the level of frost stored towards house and you can as a result of thermal extension. Sea level a reaction to temperature pushing for the past 0.5 Ma could have been read playing with proxy data from ice cores, water sediments, and fossil corals [ Rohling ainsi que al., 2009 ; Siddall et al., 2010a , 2010b ]. Although not, for extended episodes (10 6 –ten seven years), merely modeled quotes have been had written, albeit constrained of the data [ de- Boer ainsi que al., 2010 ]. Right here i play with existing proxy records throughout the past fifty Ma to research the relationship and concerns ranging from temperature and you can sea level inside the transition to a keen “ice house” business. There are not any all over the world associate temperature proxies on this subject timescale; rather, we browse the the relationship having fun with DST and you will facial skin temperatures of large and lowest latitudes.

When examining so it lifetime period, the brand new proxy listing out of body climate is restricted in both cycle and you may spatial coverage, although facts are boosting with the proceeded development of brand new and you can present proxies [ Lear et al., 2008 ; Liu et al., 2009 ]. A limitation of utilizing isolated facial skin temperatures proxies is that indeed there was intrinsic uncertainties about if or not local and you can/or regular heat movement are increasingly being registered [ Lear mais aussi al., 2000 ]. These types of potential biases is actually reduced in brand new DST list, while the DST checklist enjoys other high constraints [ Lear ainsi que al., 2000 ; Billups and Schrag, 2003 ]. DST are coupled so you’re able to SST at regions of deep-liquid creation, hence into contemporary was mainly, not exclusively [ Gebbie and you can Huybers, 2011 ], brand new high latitudes [ Zachos mais aussi al., 2001 ]. For this reason, DST proxies really should not be named an eye on previous all over the world temperatures however, is to instead be considered due to the fact analogous to early in the day high-latitude surface temperatures [ Zachos mais aussi al., 2001 ]. Brand new DST number is right when exploring the ocean height in order to temperature dating, because it’s better paired with the body at the areas of frost formation.

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step 1.2. Feedback Description

Most that it review means the DST so you can sea level dating for the past fifty Ma, as DST list is much more complete compared to skin temperature list. At the same time, i have a look at the surface temperature to sea-level relationships more than a great secret interval to have sea-level change, the fresh new Eocene-Oligocene change (EOT). The newest lead interpretation between your DST in order to sea-level relationship to the surface heat so you can sea level matchmaking is dependent on the life out of a steady strong-water to help you surface temperature gradient as a consequence of day. I is a dialogue of how deep-water so you can skin heat gradient may have altered along the multimillion seasons timescale of investigation due to alterations in ocean flow and you can switching resources of deep-drinking water formation [ Cramer ainsi que al., 2009 ; Katz et al., 2011 ].