Question: How does the the sea levels in the early Pliocene compare to today?
About the article "Climate change", section "Sea level change".

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The Pannonian Sea was a shallow ancient sea located in the area today known as the Pannonian Plain in Central Europe.
The Pannonian Sea existed during the Miocene and Pliocene epochs, when three to four kilometres of marine sediments were deposited in the Pannonian Basin. 
 Peninsula fossils.
Some 12 to 4 million years ago, during the Late Miocene to Early Pliocene, a highly endemic vertebrate fauna evolved on what was then Gargano Island due to higher sea levels than today.
Several of these animals were subject to island gigantism.
The fossils are found in partially infilled paleokarst fissures across Monte Gargano.
The Gargano Island fauna is known as "Mikrotia" fauna after an endemic rodent genus of the area.
Initially named "Microtia", this had to be corrected, because the genus name "Microtia" was already used for butterflies.
The surface features of the ancient karst developed in Mesozoic limestone.
In these, sediment accumulated together with the remains of the local fauna, forming thick layers of reddish, massive or crudely stratified silty-sandy clays, known as "terrae rossae" ("red soils").
Through the mid-Pliocene, some of these deposits were flooded, probably due to tectonic movement of the Apulian Plate.
Others were overlaid by other sediments of terrestrial or freshwater origin.
In this way a buried, partially reworked paleokarst originated.
Later, as the ice ages cycle got underway, sea levels sank and the former island was continentalized.
In the cool and semiarid conditions of the Early Pleistocene (some 1.8 - 0.8 mya) a second karstic cycle occurred, producing the neokarst which removed part of the paleokarst fill. 
Global sea level change for much of the last century has generally been estimated using tide gauge measurements collated over long periods of time to give a long-term average.
More recently, altimeter measurements — in combination with accurately determined satellite orbits — have provided an improved measurement of global sea level change.
To measure sea levels prior to instrumental measurements, scientists have dated coral reefs that grow near the surface of the ocean, coastal sediments, marine terraces, ooids in limestones, and nearshore archaeological remains.
The predominant dating methods used are uranium series and radiocarbon, with cosmogenic radionuclides being sometimes used to date terraces that have experienced relative sea level fall.
In the early Pliocene, global temperatures were 1–2˚C warmer than the present temperature, yet sea level was 15–25 meters higher than today.
He is well known for originating the four questions he believed should be asked of any animal behaviour, which were:  1.
Causation (Mechanism): what are the stimuli that elicit the response, and how has it been modified by recent learning?
How do behaviour and psyche "function" on the molecular, physiological, neuro-ethological, cognitive and social level, and what do the relations between the levels look like?
(compare: Nicolai Hartmann: "The laws about the levels of complexity")  2.
Development (Ontogeny): how does the behaviour change with age, and what early experiences are necessary for the behaviour to be shown?
Which developmental steps (the ontogenesis follows an "inner plan") "and" which environmental factors play when / which role?
(compare: Recapitulation theory)  3.
Function (Adaptation): how does the behaviour impact on the animal's chances of survival and reproduction?
4.
Evolution (Phylogeny): how does the behaviour compare with similar behaviour in related species, and how might it have arisen through the process of phylogeny?
Why did structural associations (behaviour can be seen as a "time space structure") evolve in this manner and not otherwise?
* In ethology and sociobiology causation and ontogeny are summarized as the "proximate mechanisms" and adaptation and phylogeny as the "ultimate mechanisms".
They are still considered as the cornerstone of modern ethology, sociobiology and transdisciplinarity in Human Sciences. 
The Hazelhurst terrace and shoreline (formerly the Brandywine) was assigned by C. W. Cooke and includes Vernon's Coastwise delta plain andMacNeil's high Pliocene terrace.
Deposits are found between 97 to 65.5 meters (320–215 feet).
During the interstadial period of late Pliocene to early Pleistocene epoch, the Hazelhurst terrace and shoreline was created in many counties east to west.
Gadsden in particular had a very large land mass not only created by rising and lowering sea levels, but from depositions from the Apalachicola River on Gadsden's west side.
Leon County remained completely submerged.