How does rising atmospheric CO2 affect marine organisms?

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Antarctic Icebergs
Long, D.G., Ballantyne, J. and Bertoia, C.  2002.  Is the number of Antarctic icebergs really increasing?  EOS, Transactions, American Geophysical Union 83: 469, 474.

According to Bindschadler and Rignot (2002), the production of icebergs in the vicinity of Antarctica "appears to be on the rise in recent years, increasing concern that this phenomenon portends some recent climatic trend."  This perception is also supported by data from the National Ice Center (NIC), as noted by Long et al. (2002).

What was done
The authors used recently developed techniques that employ enhanced radar scatterometer data to address the question of whether the increasing number of icebergs reported by the NIC reflects a climate trend or changes in observation tools.

What was learned
The authors conclude that "technological advances in iceberg observation and tracking techniques explain much of the NIC's increasing iceberg count through 1999," while noting that the rest of the increase is "clearly linked to episodic calving events," which they describe as "an expected phenomenon," since "major calvings occur every 50-100 years as an ice sheet advances into the ocean (Jacobs et al., 1986)."  In this regard, for example, they note that "the recent 10 May 2002 calving of C19 along the edge of the Ross Ice Shelf was expected and probably finishes the Ross Ice Shelf reduction initiated by the 1998 and 2000 calvings," with respect to which they report that "a relationship between the formation of large, tabular icebergs and climate trends has not been established (Lazzara et al., 1999)."

What it means
Nothing unusual has been happening with respect to iceberg formation around Antarctica over the past quarter century.  Indeed, the authors specifically and emphatically state "we cannot conclude that the apparent increase in the number of icebergs represents a climate trend."

What it means
Bindschadler, R.A. and Rignot, E.  2001.  "Crack!"  in the polar night.  EOS, Transactions, American Geophysical Union 82:497-498,505.

Jacobs, S.S., MacAyeal, D.R. and Ardai Jr., J.L.  1986.  The recent advance of the Ross Ice Shelf.  Journal of Glaciology 32: 464-474.

Lazzara, M.A., Jezek, K.C., Scambos, T.A., MacAyeal, D.R. and van der Veen, C.J.  1999.  On the recent calving of icebergs from the Ross Ice Shelf.  Polar Geography 23: 201-212.

Reviewed 8 January 2003