During 1872 and 1876,
Challenger expedition started the modern marine survey and marked the foundation of
oceanography. Since then, scientific exploration of the oceans have made many discoveries. At the end of the 19th century, America built the to carry out ocean surveys. In 1893, Norwegian scientist
Fridtjof Nansen fixed his
Fram in the Arctic ice-cap for three years to undertake long-term observations of oceanographic, meteorological and astronomical data. One of the first acoustic measurements of the ocean floor was in 1919. From 1925 to 1927, the
Meteor expedition used echo sounders to measure 70000 ocean depth measurements and explore the
Mid-Atlantic Ridge. In 1953,
Maurice Ewing and
Bruce Heezen discovered the global ridge system extending along the Mid Atlantic Ridge. In 1960,
Harry Hammond Hess developed the seafloor spreading theory by ocean exploration.
Deep Sea Drilling Project started in 1968. In the recent years, oceanographic investigation has revealed that ocean environment is changing, like
Ocean acidification, water temperature,
Carbon cycle,
Sea level rise. Oceanographers are trying to find solutions to these changes by ocean exploration. However, it is hard to understand the whole system in one single subject because the ocean environment is balanced by both its physical conditions and chemical conditions, which is an essential factor for the diversities of marine biology. For example, if the temperature in the ocean surface rises, it would affect the
Nutrients distributions,
Mixed layer depth,
Ocean current,
pH conditions,
Salinity distributions and so on. Those series of ocean environment changes could even cause dramatic decrease of some
Species and effect on the entire
Food web in the ocean. Scientists have many assumptions and predictions about the consequences of climate changes in ocean but only by long-term ocean exploration can testify these assumptions. On the other hand, the ocean is large, which accounts for about 97.2% of the Earth's water resources and covers more than 70% of the Earth's surface (
Water distribution on Earth), and connected with each other. If one of the oceans changes, the others would also be influenced. Thus it is necessary to use global ocean data to measure how one change can have influence on the others. However, ocean exploration is costly and no one single country can afford continuous yearly global ocean cruises themselves. Therefore, GO-SHIP as one of global ocean observation and exploration programs was launched. Except for GO-SHIP, there are other programs such as
World Ocean Circulation Experiment,
Tropical Ocean Global Atmosphere program,
Argo (oceanography), NPOCE,
Global Ocean Observing System and
International Ocean Discovery Program. ==Contributions and discoveries==