科学前沿

According to the recent global mean surface temperature curve [1], the temperature continued to rise over a period of 45 million years at the end of the Paleozoic. The global mean temperature increased from 11.7 C at 295 Ma at the beginning of the Permian to 32.7 C at 250 Ma at the beginning of the Triassic, a warming of 21 C, one of the most dramatic warmings in the Phanerozoic (Fig. 1a), which is referred to in this paper as the end-Paleozoic great warming (EPGW). Another significant warming event occurred in the mid-Cretaceous, when the global average temperature rose by 8.8 C in 8 million years, reaching 28.2 C. The other two warming events of similar magnitude occurred after cooling events such as the Hirnantian Ice Age and the Cretaceous-Paleogene impact winter. Although the warming magnitudes were large, they mainly started from low points and did not exceed 25 C after the warming events (Fig. 1a). Other warming events with much smaller magnitudes include the early Cambrian, early Silurian, mid-late Silurian, Emsian, mid-Devonian, Frasnian, Devonian-Carboniferous, early Pennsylvanian, Carnian, Norian, end-Triassic, Toarcian, Oxfordian, early Cretaceous, Albian, earliest Paleocene, Paleocene-Eocene, and Oligocene (Fig. 1b). In addition to the great warming events, there have been several great cooling events, namely the early Paleozoic, late Paleozoic, and Cenozoic great cooling events. The duration of these major cooling events ranged from 36 to 78 million years, with global mean temperature decreases of 11.2–16.5 C (Table 1). These three major