© Jeremy ShakunThis graph shows Antarctica warming up slightly before atmospheric carbon dioxide rose and well before global temperatures warmed. In a new study, researchers explain that a change in the Earth's orbit resulted in a change in ocean circulation that prompted the Antarctic to warm before the rest of the planet.
The circumstances that ended the last ice age, somewhere between 19,000 and 10,000 years ago, have been unclear. In particular, scientists aren't sure how carbon dioxide, a greenhouse gas, played into the giant melt.
New research indicates it did in fact help drive this prehistoric episode of global warming, even though it did not kick it off. A
change in the Earth's orbit likely started of the melt, setting off a chain of events, according to the researchers.
The ambiguity about the end of the ice age originates in the Antarctic. Ice cores from the continent reveal a problematic time lag: Temperatures appeared to begin warming before atmospheric carbon dioxide increased. This has led scientists to question how increasing carbon dioxide -
a frequently cited cause for global warming now and in the distant past - factored into the end of the last ice age. Global warming skeptics have also cited this as evidence carbon dioxide produced by humans is not responsible for modern global warming.
But the data from Antarctica alone offer too narrow a perspective to represent what was happening on a global scale, according to lead study researcher Jeremy Shakun of Harvard University.
"These ice cores only tell you about the temperatures in Antarctica where they are from, and if you think about today the same way, you don't want to look at one thermometer record from London or New York to prove or disprove global warming," Shakun said during a press conference on Tuesday (April 3).
Comment: Interesting that the main stream media is slowly letting the news out. Quite a number of real scientists are in agreement that the earth has actually been cooling and that we are due for another ice age in the very near future (among other things!):
Ice Ages Start and End So Suddenly, "It's Like a Button Was Pressed," Say Scientists
Reflections on the Coming Ice Age
'Forget global warming, prepare for Ice Age'
Scientist predicts 'mini Ice Age'