Scientists revealed that the ocean surface changes passed by the sudden heat of the nearly forty years, but they do not know exactly why.
The scientists noted that the surface layers of the waters of the northern hemisphere has seen a drop in temperature was about one-third degree Celsius, while there was water in the oceans south of the earth rise almost equally.
The scientific research team whose research published in the journal Nature (Nature) scientific, that air pollution can not be the cause of those changes, and that there had occurred in the cooler mid-twentieth century, according to the stated location, "the BBC".
The scientists admitted they do not know the reason behind those changes, it is also known that this was connected to all the oceans.
Those changes have been recorded, which is called the great salt changes during the past few decades in the northern part of the Atlantic Ocean, and one of them appeared in the seventies.
The records showed the heat in the Earth during the seventies that there is a period where the cold surface of the earth in the northern part, whereas the southern part of the hottest relative.
Scientists say that the difference in temperature was probably due to the release larger quantities of products "aerosol", the dusts and particles, industrial, ultra-slim, in the northern hemisphere, where most industrial production in the world.
The "aerosol" reduce the temperature of the Earth's surface otherwise the solar radiation back into space instead of Earth, but the sudden changes, recorded by scientific research, which was supervised by Dave Thompson of the University of Colorado in Fort Collins, the U.S., indicating that the interpretation of the phenomenon may be found elsewhere, on the grounds that the effect of "aerosols" and its effectiveness to occur on a more gradual and not sudden.
Professor Thompson told the BBC: "We can not exclude other reasons, those reasons may be of critical importance and essential, it is difficult to accept the idea that these sudden changes can be done from the aerosol, which has different capabilities."
The sweet water entered through the seventies to the northern part of the Atlantic Ocean, leading to reduced salinity of the water in that region. With the entry of large amounts of fresh water into the ocean can slow down the share of the Atlantic in what is known to contribute to the phenomenon of thermal recycling.