Scientists Warn of Rising Oceans as Antarctic Ice Melts - NYTimes.com
Geege Schuman stashed this in Climate
Two papers scheduled for publication this week, in the journals Science and Geophysical Research Letters, attempt to make sense of an accelerated flow of glaciers seen in parts of West Antarctica in recent decades.
Scientists said the ice sheet was not melting because of warmer air temperatures, but rather because of the relatively warm water, which is naturally occurring, from the ocean depths. That water is being pulled upward and toward the ice sheet by intensification of the winds around Antarctica.
So which is it? Are we all going to die under an Antarctic torrent of floodwaters, or is the Antarctic ice pack enjoying record highs?
We're not going to die in floodwaters in our lifetime.
But the oceans are definitely rising -- the Antarctic ice pack rise is an anomaly that has no logical scientific explanation for now:
The increasing ice is especially perplexing since the water beneath the ice has warmed, not cooled.
“The overwhelming evidence is that the Southern Ocean is warming,” said Jinlun Zhang, a University of Washington scientist, studying Antarctic ice. “Why would sea ice be increasing? Although the rate of increase is small, it is a puzzle to scientists.”
In a new study in the Journal of Climate, Zhang finds both strengthening and converging winds around the South Pole can explain 80 percent of the increase in ice volume which has been observed.
“The polar vortex that swirls around the South Pole is not just stronger than it was when satellite records began in the 1970s, it has more convergence, meaning it shoves the sea ice together to cause ridging,” the study’s press release explains. “Stronger winds also drive ice faster, which leads to still more deformation and ridging. This creates thicker, longer-lasting ice, while exposing surrounding water and thin ice to the blistering cold winds that cause more ice growth.”
But no one seems to have a conclusive answer as to why winds are behaving this way.
“I haven’t seen a clear explanation yet of why the winds have gotten stronger,” Zhang told Michael Lemonick of Climate Central.
Some point to stratospheric ozone depletion, but a new study published in the Journal of Climate notes that computer models simulate declining – not increasing – Antarctic sea ice in recent decades due to this phenomenon (aka the ozone “hole”).
Ultimately, it’s apparent the relationship between ozone depletion, climate warming from greenhouse gases, natural variability, and how Antarctic ice responds is all very complicated. In sharp contrast, in the Arctic, there seems to be a relatively straight forward relationship between temperature and ice extent.
Overall, oceans are rising.
And parts of the Antarctic ice sheet are melting.