In 1873, the British warship HMS Challenger, refitted by the Royal Society of London and the Royal Navy as an oceanographic laboratory, set sail on a 4-year voyage of discovery. She sailed to the oceans in every part of the world, taking depth soundings, profiling the ocean floor, and collecting over 4,000 species and sediment samples. Challenger scientists also took seawater temperatures in 273 locations.
In April, 2012, a study by the Scripps Institution of Oceanography at UC San Diego compared the ocean temperatures taken by HMS Challenger 130 years before with those recorded in the same locations by ARGO, a network of 3,500 free-floating robotic buoys spotted around the world, during the 7-year period 2004-2010.
At the surface, down to 2,300 ft (700m), the average temperature increase was 1.1°F (0.59°C). The difference diminished with depth, disappearing altogether at 5000 ft (1500m). While the surface increase may not seem large, it is scientifically significant, contributing to the volume expansion of ocean water, and the rise in sea levels around the world. Along with the 1.5°F (0.8°C) rise in global air temperature during approximately the same period of time, the warmer ocean temperatures have speeded up the melting of polar ice sheets and glaciers, and boosted the rate of seawater evaporation and cloud formation, making storms such as hurricanes and tornadoes bigger and stronger, and therefore much more deadly.
Computer models project a continuing steady increase in both air and ocean temperatures for the remainder of the 21st Century. The U.S. space shuttle Challenger was named in honor of the famous British ship.