14 DAY TRIAL // The movement of the Earth's molten interior could play a very important role in sea level change in the past 2 to 20 million years, according to an Australian scientist.
Geophysicist Professor Dietmar Müller from University of Sydney says that sea levels vary depending on Earth's natural processes that can take up to hundreds of millions of years, and that in the past, sea level was over 120 meters higher than nowadays.
“The reality is we live on a dynamic planet - even in the absence of human-induced warming, sea levels would still change dramatically because it's been doing it for a very long time,” Müller said in the article published in the journal Science today.
“This paper points this out, controlling and taming the planet is to some extent a futile exercise [and] if you want to develop intelligent responses [to climate change] we need to identify our own contributions to sea level change from natural fluctuations.”
He adds that even though the very short and long term causes of the sea level changes are understood, there might be cycles of change between 2 and 20 million years whose causes are yet unknown.
Nevertheless, Müller and his colleagues found that these cycles are too slow to be caused by melting ice and too fast for the progressive growth and the destruction of volcanic ridges in the middle of ocean basins, ABC Science reports.
The explanation for these new discovered cycles was found by Dr Kenni Petersen from Aarhus University, Denmark who's published research concludes that sea levels change at a regional scale because of the heat that comes from below the Earth's crust and forces sea floor to rise.
The International Drilling Program, that has already drilled a line of cores into sea floor off the coasts of New Jersey and the South Island of New Zealand, could establish if the sea level change is global or local as Petersen suggests, but there is not enough information for now.
Professor Kurt Lambeck, a geophysicist at the Australian National University in Canberra, appreciates Petersen's work on the matter and says that it could turn out to be “an important part of our understanding of long-term sea level change.”
He adds though that these changes have “no consequence on the human timescale” and that “what's important is the rate of change, which is now several millimeters per year, several orders of magnitude more than in has been in the past.”