What may have caused global sea levels to rise from the Early to Late Jurassic?

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Jurassic paleogeography — Jurassic Period Distribution of landmasses, mountainous regions, shallow seas, and deep ocean basins during the late Jurassic Period. Included in the paleogeographic reconstruction are the locations of the interval's subduction zones.

Some geologists have proposed that global sea levels increased from the Early to Late Jurassic. Because there is no evidence of major glaciations during this period, any rise in global sea level is attributed to two primary factors:1

Thermal expansion: As global temperatures were generally warm throughout the Jurassic, the thermal expansion of seawater likely contributed to higher sea levels.12
Plate tectonic activity: Increased activity at spreading centres and oceanic ridges, which produced new seafloor, may have displaced water and raised sea levels.13

While records of sea level changes exist on every continent, it remains difficult to correlate local changes to global trends due to the significant tectonic activity occurring during this time.1