Unfortunately, these records are invariably short, of the order of centuries at best, and can be associated with age uncertainties of 1 or 2 %. (ipcc.ch)
«The reason this study is so exciting is that previous methods of reconstructing ocean heat content have very large age uncertainties, [which] smooths out the more subtle features of the record,» said co-author Sarah Shackleton, a graduate student in the Severinghaus lab at Scripps. (constantinealexander.net)
Up until now, instrumental observations of the oceans have only spanned the last 100 years or so, whilst reconstructions using marine sediment cores come with significant age uncertainties. (sciencedaily.com)