We have a whole fleet of submersible thermometers that dive down to 2000 meters. And it's not that hard to tie a thermometer to a lead sinker and take a deep ocean temperature.
We don't even have 20 years' worth of data. As far as historical data, nothing at all.
"In 1999, to combat this lack of data, an innovative step was taken by scientists to greatly improve the collection of observations inside the ocean through increased sampling of old and new quantities and increased coverage in terms of time and area.
"In 1999, to combat this lack of data, an innovative step was taken by scientists to greatly improve the collection of observations inside the ocean through increased sampling of old and new quantities and increased coverage in terms of time and area.
That step was Argo. "