Arctic Ocean ice floes. (Photo: NOAA)
Tropical oceans are driving climate change: study
Friday, July 06, 2012, 15:20 (GMT + 9)
Oceans across the globe are increasingly driving tropical warm water towards the poles. This phenomenon brings significant consequences for life on Earth, tells a new study published in the Journal of the Marine Biological Association.
According to scientists at Plymouth University’s Marine Institute and the National Centre for Scientific Research (CNRS), the tropical regions of the Indian, Pacific and Atlantic Oceans appear to be “acting like a heart”: accumulating heat and then pumping warm water in bursts.
When the water hits continental shelves, it is redirected along the shelf-line and towards the poles. Scientists say many of the pulses coincide with El Niño events – and that their heat content is rising.
Lead author of the report Professor Philip Reid, of the Sir Alister Hardy Foundation for Ocean Science (SAHFOS) and the Marine Institute, said the phenomenon explains the timing and connection of a series of observed hydrographic, ecosystem and cryospheric (frozen ice/snow) events.
“We have described for the first time a globally synchronous pattern of pulsed, short-term (one-year) emanations of warm temperatures that pass along continental shelves, from tropical seas to the poles,” he elaborated. “Warm tropical waters appear to be acting like a heart, accumulating heat and energy, and then pumping it in bursts that progressively move toward the poles, a process that seems to be accelerating.”
Reid and research partner Dr Gregory Beaugrand mapped and statistically analysed average temperatures for every two-degree square of latitude and longitude for the whole global ocean, from 1960 until 2008, with a finer single degree resolution along continental shelves.
They found an outstanding degree of symmetry on both sides of the equator and very clear spikes in the temperature followed by a period of cooling.
Beaugrand said they found sudden increases in temperatures in 1976, 1987, 1998 and during 2000-10 that coincided with ecosystem changes, such as the collapse of the cod fishery off Eastern Canada in the late 1980s.
“If this pattern continues, global temperatures may continue to rise in sudden jumps – and the evidence suggests that the rate of rise is accelerating,” Reid concluded.
Meanwhile, researchers believe that plants are evolving rapidly to changing conditions, which could improve their chances of survival. A new study shows that Australian plant leaves of a type of Dodonaea viscosa -- an Australian shrub in the Lychee family -- are shrinking, New Scientist reports.
"We've already seen substantial changes in the Earth's climate and so we should expect that there have been changes to the Earth's plants," said Andrew Lowe, a plant conservation biologist at the University of Adelaide in Australia and a key investigator on the study.
"The study is a new example of significant climate change responses to date," said co-author Greg Guerin, also from the University of Adelaide, BBC reports. "We now know that every degree of warming is ecologically significant and generating ecological disequilibrium.
By Natalia Real
Photo Courtesy of FIS Member National Oceanic and Atmospheric Administration NOAA/NMFS