Washington: A team of physicists at the University of Rochester, US, has found evidence that in the last 50 years, the net flow of heat into and out of the oceans has changed direction three times, which correlate well with past climate anomalies.
According to the researchers, these shifts in the balance of heat absorbed from the sun and radiated from the oceans correlate well with past anomalies that have been associated with abrupt shifts in the earth’s climate.
These anomalies include changes in normal storm intensities, unusual land temperatures, and a large drop in salmon populations along the western United States.
The physicists also said that these changes in ocean heat-flow direction should be taken into account when predicting global climate because the oceans represent 90 percent of the total heat in the earth’s climate system.
The study differs from most previous studies in two ways.
First, the physicists look at the overall heat content of the Earth’s climate system, measuring the net balance of radiation from both the sun and Earth.
And second, it analyses more completely the data sets the researchers believe are of the highest quality, and not those that are less robust.
“These shifts happened relatively abruptly,” said David Douglass, professor of physics at the University of Rochester.
“One, for example, happened between 1976 and 1977, right when a number of other climate-related phenomenon were happening, such as significant changes in US precipitation,” he added.
Douglass said the last oceanic shift occurred about 10 years ago, and that the oceans are currently emitting slightly more radiation than they are receiving.
The members of the team believe that these heat-flux shifts had previously gone unnoticed because no one had analysed the data as thoroughly as the Rochester team has.
The team believes that the oceans may change how much they absorb and radiate depending on factors such as shifts in ocean currents that might change how the deep water and surface waters exchange heat.
In addition to the correlation with strange global effects that some scientists suspect were caused by climate shifts, the team said that their data shows the oceans are not continuously warming—a conclusion not consistent with the idea that the oceans may be harbouring “warming in the pipeline.”
Douglass further noted that the team found no correlation between the shifts and atmospheric carbon dioxide concentration.
ANI
