In a perspective on Quaternary climate change with Tom Chalk, published in the Encylopedia of Quaternary Science, we question the conventional wisdom that ice ages result from regular changes in Earth’s orbit or some other purely physical mechanism. We argue instead that the global carbon cycle and greenhouse gasses need to be included as a cause of climate change.
In a new synthesis review with Danny Sigman, published in the Oxford Research Encyclopedia of Climate Science, we entertain the possibility that changes in the ocean’s biological pump and alkalinity were the dominant driver of CO2 and global climate change during Pleistocene ice ages. We show that land-carbon changes effects were canceled by ocean carbonate compensation, and that ice sheet and temperature changes cancel each other. The effect of deep ocean carbon storage, in contrast, is amplified by carbonate compensation, yielding durable CO2 changes.