The oceans hold the vast bulk of the heat in the climate system. We’ve only been measuring ocean temperature properly since mid-2003, when the Argo system became operational.[9] [10] In Argo, a buoy duck dives down to a depth of 2,000 meters, measures temperatures as it very slowly ascends, then radios the results back to headquarters via satellite. Over three thousand Argo buoys constantly patrol all the oceans of the world.