Does the Atlantic Hold the Answer to the Temperature Hiatus?

Tuesday 26th Aug 2014 by theWeather Club
Image: A jellyfish floats just above the seafloor of the deep Atlantic Ocean (Source: NOAA/OAR/OER via Wikimedia Commons)

 

Despite continued increasing levels of atmospheric CO2 and the confirmed link with increasing global temperatures, the rate of global warming has slowed recently, commonly referred to as the ‘temperature hiatus’. Researchers have been searching for the underlying cause of this slowdown, with suggestions of incomplete measurements, natural cycles such as La Niña, weaker solar irradiance, trade winds and Pacific ocean sinks all providing possible explanations (A recent Nature Geoscience letter can be found here). However, a recent study may hold the key.

Scientists in China and the US may have found where the extra heat is going: the bottom of the Atlantic and Southern Oceans. The paper, published in the journal Science, analysed millions of ocean measurements of temperature and salinity since 1970 and tracked the heat pathways since the early 21st Century. They argue that a sudden shift in ocean salinity could have triggered the transfer of heat to very deep waters, since this corresponds with the slowdown in increasing global temperatures. Since water with a higher salinity is more dense, it sinks faster thereby taking heat with it as is falls to a lower depth. The work also suggests that the ‘cooling period’ associated with this heat-sequestration mechanism could last 20-35 years.

Oceans cover 70% of the planet and are capable of storing 90% of the planets heat and it has long been known that heat cycles naturally within the ocean, eventually rising back to the surface. The novelty with this piece of research is that the Pacific Ocean was originally thought to be the main ‘hiding place’ for heat - the role of the Atlantic and Southern Oceans were not previously the main suspects. Of course, as for all scientific research, more analyses and studies will be required before it is fully accepted, but it certainly adds more evidence for the role of ocean circulation in global climate.

The full journal article can be found here >> http://www.sciencemag.org/content/345/6199/897