The PETM was a period of geologically-rapid global warming that punctuated a warming Eocene climate 55.8 Ma ago (Charles et al., 2011), and saw sea surface temperatures rise by 5–8 °C from background levels (Zachos et al., 2005; Sluijs et al., 2007). It was associated with a substantial injection of δ13C-depleted carbon into the ocean-atmosphere system (see Pagani et al., 2006a) over <20 ka (Cui et al., 2011), causing a negative carbon isotope excursion (CIE) between −2 and −7‰ in marine and terrestrial sediments (see overview in Schouten et al., 2007) lasting 170 ka (Röhl et al., 2007), and a prominent dissolution horizon in the deep sea signifying deep ocean acidification (Kennett and Stott 1991; Zachos et al., 2005). The source and rate of released carbon are still under debate (Pagani et al., 2006a; Zeebe et al., 2009; Cui et al., 2011), but may have been linked to the dissociation of marine hydrates containing biogenic methane (δ13C of<−60‰) (Dickens et al., 1995), thermogenic methane from marine sediments around the Norwegian Sea (Svensen et al., 2004), or dissolved methane from a silled Kilda Basin between Greenland and Norway (Nisbet et al., 2009).
PETM
55.8 Ma
Ma
sea surface temperatures
rise
5–8 °C
°C
δ13C-depleted carbon
substantial injection
over <20 ka
ka
marine and terrestrial sediments
negative carbon isotope
between −2 and −7‰
‰
negative carbon isotope excursion (CIE)
lasting
170 ka
ka
marine hydrates containing biogenic methane
δ13C
<−60‰
‰