A four-year oceanographic survey, carried out 140 years ago by HMS Challenger, takes 263 serial water temperature observations – using then current technology. Now, using data from 3,500 free-drifting profiling Argo floats, employing current technology, a temperature differential of 1.1°F (0.59°C) since the 1870s is calculated.
However, this is climate science, so no awkward questions are permitted. We are not allowed to know whether instrument and procedural errors are comparable and have been adequately compensated for. Nor do we entertain any possibility that temperature variations over term may include cyclical variations, and comparisons are being made between different points in a cycle
Instead, we get a report in Science Daily, which is copied out verbatim in the Daily Wail - whole passages copied out word for word (see above). That passes for journalism. And if one wants to check the details, it will cost you $18 from Nature - but you'll be none the wiser. More to the point, those that have decided to believe will continue to believe regardless.
For the rest, I suspect that no one is going to get particularly worked up about an annual increase of 0.0042°C in ocean temperature, even if it is real. For Mr Average, this is a non-event.