At present, these feedbacks are not tightly constrained by available observations. (ipcc.ch)
Also included were other peer - reviewed assessments and research, as well as government statistics, publicly available observations, and advice from expert reviewers. (pnnl.gov)
However, our understanding of how the ocean impacts the global mean surface temperature is strongly limited by available observations, which historically have consisted primarily of sea surface temperature (SST) measurements. (pnas.org)