How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic

Breakup of Small Antarctic Ice Shelves Is Not Evidence of Anthropogenic Climate Change
Pudsey, C.J. and Evans, J.  2001.  First survey of Antarctic sub-ice shelf sediments reveals mid-Holocene ice shelf retreat.  Geology 29: 787-790.

Five small Antarctic Peninsula ice shelves have been retreating during the period of historical observations, i.e., since about 1843.  This retreat intensified in the late 1980s, and was followed by the breakout of two of them (Larsen-A and Prince Gustav Channel) in 1995.  The current study was conducted in an attempt to determine the uniqueness of these phenomena.

What was done
The authors studied ice-rafted debris obtained from four cores in Prince Gustav Channel, which was formally (until 1995) covered by floating ice shelves.

What was learned
It was determined that the Prince Gustav Channel ice shelf also retreated in mid-Holocene time, but that, in the words of the authors, "colder conditions after about 1.9 ka allowed the ice shelf to reform."

What it means
Although the authors conclude that the ice shelves in question are sensitive indicators of regional climate change, they are careful to point out that "we should not view the recent decay as an unequivocal indicator of anthropogenic climate change."  The disappearance of the ice shelves is not unique; it's happened before without our help, and it could well have happened again on its own.  In fact, the breakup of the Prince Gustav Channel ice shelf could be nothing more than the natural culmination of one aspect of the Antarctic Peninsula's recovery from Little Ice Age-like conditions, as similar phenomena have been observed in many places throughout the Northern Hemisphere and other parts of the Southern Hemisphere as well (see Little Ice Age in our Subject Index).