Key to Climate Change are Ocean Temperature Patterns

The role of sensitive triggers built into our climate system that can cause abrupt shifts in global climate has been uncovered by an analysis of past oceanic temperature patterns.

"Evidence is mounting that the Earth's climate system has sensitive triggers that can cause abrupt and dramatic shifts in global climate," said geological oceanographer Matthew Schmidt from Texas A&M University.

He points out that if ocean temperatures were to warm along the west coast of Africa, the monsoon rainfall in that region would be dramatically reduced, affecting millions of people living in sub-Saharan Africa, the journal Proceedings of the National Academy of Sciences reports.

He also adds that the southward flow of ocean heat during cold periods in the North Atlantic also causes the band of rainfall in the tropics known as the Intertropical Convergence Zone (ITCZ) to migrate southward, resulting in much drier conditions in northern South American countries and a wetter South Atlantic.

The ITCZ, known by sailors as the doldrums, is the area encircling the earth near the equator where winds originating in the northern and southern hemispheres come together, according to a Texas statement.

Schmidt and two of his graduate students teamed up with Ping Chang, physical oceanographer and climate modeler, to help uncover an important climate connection between the tropics and North Atlantic.

They used geochemical clues in fossils of tiny sea creatures with a hard shell, collected from a sediment core located off the northern coast of Venezuela to generate a 22,000-year record of past ocean temperature and salinity changes in the upper 1,500 feet of water in the western tropical Atlantic, according to a Texas statement.

"What we found was that subsurface temperatures in the western tropical Atlantic rapidly warmed during cold periods in the Earth's past. When the tropics warmed, it altered climate patterns around the globe," Schmidt explains.

Source: IANS