Examining the Complexity of Environmental and Biotic Change during the Late Paleozoic and Early Mesozoic

The late Paleozoic and early Mesozoic was a time of tremendous upheaval on Earth with severe climatic change and biotic crises. The late Paleozoic Ice Age (LPIA) is arguably one of the most important events of the Phanerozoic as it is the most widespread and longest-lived glaciation. Two extinction events at the end of the Permian together comprise the largest mass extinction of the Phanerozoic.

Atmospheric CO₂ was a driver for late Paleozoic fluctuations in ice volume and ultimate deglaciation, the late Paleozoic mass extinctions, and the prolonged early Mesozoic environmental perturbations. Evidence shows a strong link between pCO₂, glacial/non-glacial periods, the final deglaciation phase, and ecological changes among the terrestrial and marine biota of the LPIA. Atmospheric CO₂ levels rose during the Late Permian into the Early Mesozoic and facilitated global warming, development of a vertically stratified ocean, and short-term and long-term ecological changes during the Middle Permian to Early Triassic. Thus, although these events are often considered as separate entities, we propose that these changes are part of an environmental continuum of products resulting from a common driving mechanism.

One major question in future climate change studies concerns thresholds: Will Pleistocene-like environmental cyclicity continue, or will a tipping point be exceeded thereby resulting in environmental upheaval and disruption of the biosphere? Because the LPIA marks the only complete icehouse to greenhouse cycle on a vegetated Earth, studies of LPIA strata and biota provide a deep time perspective on the potential conditions and driving mechanisms of current climatic perturbations. Field work focused on the LPIA record of the western and eastern margins of Gondwana may reveal the mechanisms driving cyclic environmental behavior during the LPIA versus those that caused post-glacial and abrupt end-Permian environmental turmoil, which terminated previously established patterns.