These early Permian summer water temperatures, and hence seasonal ranges, are on the high end of or exceed those Pertussis Toxin at similar latitudes (north or south) today (World Ocean Atlas 2009; Locarnini et al., 2010). More than likely, increased freshwater runoff during the summers at the lower latitudes is magnifying the apparent summer temperatures and seasonal temperature range inferred from carbonate δ18O values. Nevertheless, summers warmer than might be expected in SE Gondwana, given the presence of a waning ice sheet on the continent, could result from the influence of a large land mass in the Southern Hemisphere at this time (Crowley et al., 1986), so long as portions of the continent were ice-free and so had lower albedo. Glossopterid-dominated cold-temperate floras in SE Gondwana (Rees et al., 2002) and our observation of large fossil trees in the South Syndey Basin nearshore marine section suggests this to be the case. Coastal temperatures such as those reported here would be more subject to seasonal continental albedo effects than open ocean temperatures. The degree to which 18O-depleted freshwater runoff is augmenting calculated summer temperatures is not possible to constrain at this time.
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