Causal mechanism of ocean deoxygenation, mass extinction, and climate change

A recent work of Pohl et al. (2021) 

"........seafloor anoxia occurred during the latest Ordovician glacial maximum, coincident with the second pulse of the Late Ordovician mass extinction. However, expanded anoxia in a glacial climate strikingly contrasts with the warming-associated Mesozoic anoxic events and raises questions as to both the causal mechanism of ocean deoxygenation and its relationship with extinction."

I believe that the rate of change of the sea surface temperature is more critical in determining the expansion of bottom ocean deoxygenation, and it should also affect the ocean circulation patterns. Under two different rates of sea surface temperature changes, the emerging ocean circulation patterns and expansion of bottom ocean deoxygenation should be different. Thus, there won't be a simple relationship between Earth's climate and mass extinctions. In a nutshell, how fast the sea surface temperature changes occur can generate entirely different ocean circulation patterns, coevolving deoxygenation and mass extinctions.
 

Further reading:
 

Harper, D.A.T., 2021. Late Ordovician Extinctions, in: Encyclopedia of Geology. Elsevier, pp. 617–627. https://doi.org/10.1016/B978-0-12-409548-9.12530-8

Luo, G., Algeo, T.J., Zhan, R., Yan, D., Huang, J., Liu, J., Xie, S., 2016. Perturbation of the marine nitrogen cycle during the Late Ordovician glaciation and mass extinction. Palaeogeography, Palaeoclimatology, Palaeoecology 448, 339–348. https://doi.org/10.1016/j.palaeo.2015.07.018

Pohl, A., Donnadieu, Y., Le Hir, G., Ferreira, D., 2017. The climatic significance of Late Ordovician-early Silurian black shales: ORDOVICIAN CLIMATE AND BLACK SHALES. Paleoceanography 32, 397–423. https://doi.org/10.1002/2016PA003064

Pohl, A., Lu, Z., Lu, W., Stockey, R.G., Elrick, M., Li, M., Desrochers, A., Shen, Y., He, R., Finnegan, S., Ridgwell, A., 2021. Vertical decoupling in Late Ordovician anoxia due to reorganization of ocean circulation. Nat. Geosci. 14, 868–873. https://doi.org/10.1038/s41561-021-00843-9

Yang, X., Yan, D., Li, T., Zhang, L., Zhang, B., He, J., Fan, H., Shangguan, Y., 2020. Oceanic environment changes caused the Late Ordovician extinction: evidence from geochemical and Nd isotopic composition in the Yangtze area, South China. Geol. Mag. 157, 651–665. https://doi.org/10.1017/S0016756819001237