The role of the Poles in the global climate system: a new discovery published in Nature
A two-speed “communication” system between the Earth’s North and South Poles may explain the abrupt climate change events that have occurred throughout the planet’s history. This complex mechanism has been described in a study recently published in the journal Nature, led by Christo Buizert, Oregon State University, and which also involved Mirko Severi, University of Florence, and Barbara Stenni, Ca’ Foscari University of Venice.
Roughly 25 sudden climate change events happened on our planet in the period between 100,000 and 20,000 years ago, with abrupt temperature variations. To better understand these phenomena, the researchers analyzed ice cores from five different sites in Antarctica, comparing them with those previously extracted in Greenland.
The results showed that the abrupt climate change events occurred in that period were caused by the oceanic current that warms Greenland and Europe, by bringing warm water northwards via the Gulf Stream. When the Gulf Stream reaches its full strength, the researchers say, Greenland can warm as much as 10-15°C within a decade.
“As the heat is transferred to the north by the Gulf Stream, the rest of the oceans start to cool down”, explained Mirko Severi, University of Florence. “The phenomenon of ocean cooling affects the Antarctic continent only after 200 years. This new study shows that the climate change events taking place in the North Atlantic affect the Antarctic, on the opposite side of the Earth, via two different modes. The first one, the atmospheric mode, has a lower impact and causes the first changes in Antarctica in a few years, whereas the second one, the oceanic mode, does not manifest itself until two centuries later but has a much bigger impact”, concluded Severi.
“Observations and models suggest that today we may witness a weakening of the Gulf Stream due to climate change”, said Barbara Stenni, Department of Environmental Sciences, Informatics and Statistics at Ca’ Foscari University of Venice. “This study presents evidence of what happened in the past, which can help us understand future scenarios”.
According to the scientists, if what happened in the past were to happen again, the weakening of the Gulf Stream may decrease the strength of Asian monsoons, putting the lives of millions of people at risk. In addition, variations in the wind patterns in the southern hemisphere would reduce the ocean’s ability to absorb carbon dioxide, thus strengthening the greenhouse effect.
This study was made possible thanks to the National Antarctic Research Programme (PNRA) funded by the Ministry of Education, University and Research (MIUR), and Italy’s involvement in the two European projects European Project for Ice Coring in Antarctica (EPICA) and TALos Dome Ice CorE (TALDICE).