The Deep Sea Drilling Project (DSDP; 1966–1983) and the Ocean Drilling Program (ODP; 1983–2003) have supplied an amazing amount of information used in reconstruction of past climates, and the present Integrated Ocean Drilling Program (IODP) continues to do so. Here we compare current thinking on early Cenozoic climate (“The Greenhouse World,” ~ 65.5–33.5 million years ago [Ma]) (Figure 1) with those published 25 years ago, to highlight what we have learned in the last 25 years of drilling the ocean floor and where we face continuing challenges.

Thomas, E., H. Brinkhuis, M. Huber, and U. Röhl. 2006. An ocean view of the early Cenozoic Greenhouse World. Oceanography 19(4):94–103, https://doi.org/10.5670/oceanog.2006.08.

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