Clues to Ocean History: a Brief Overview of Proxies
9
sea floor, and using the transfer approach ofImbrie
and Kipp (1971) (Fig. 3).
More recently, the reliability of transfer functions in providing SST reconstructions has been
questioned, based on [mdings that the tropics should
have been colder during glacials than envisaged by
the CLIMAP group (Rind and Peteet 1985;
Broecker and Denton 1989; Guilderson et a!. 1994;
Stute eta!. 1995; Wolffeta!. 1998). However, other
data seem to support the CLIMAP values, for
example, temperature calculations applying the
o
5
10
alkenone method (e.g. Schneider et al. 1995), and
re-evaluations of foraminifers I statistics (Prell
1985) and foraminifersl8 18 0 values (Stott and Tang
1996). In any case, the geographic patterns are
more complicated than those presented by the
CLIMAP group (Sarnthein et a!. 1998; Gersonde
et al. 1998). Different from CLIMAP, the new
patterns reveal ice-free conditions in the eastern
Nordic Seas during LGM summer and a sea-ice
cover only reaching down to west ofIceland during winter. In the tropical divergence zone the
15
20
25
sea surface temperature eC)
Fig. 3. CLIMAP August sea surface temperatures (SSTs) for the Atlantic Ocean during the Last Glacial Maximum
(LGM). Modified according to CLIMAP (1984; http://ingrid.ldgo.columbia.edu).
9
sea floor, and using the transfer approach ofImbrie
and Kipp (1971) (Fig. 3).
More recently, the reliability of transfer functions in providing SST reconstructions has been
questioned, based on [mdings that the tropics should
have been colder during glacials than envisaged by
the CLIMAP group (Rind and Peteet 1985;
Broecker and Denton 1989; Guilderson et a!. 1994;
Stute eta!. 1995; Wolffeta!. 1998). However, other
data seem to support the CLIMAP values, for
example, temperature calculations applying the
o
5
10
alkenone method (e.g. Schneider et al. 1995), and
re-evaluations of foraminifers I statistics (Prell
1985) and foraminifersl8 18 0 values (Stott and Tang
1996). In any case, the geographic patterns are
more complicated than those presented by the
CLIMAP group (Sarnthein et a!. 1998; Gersonde
et al. 1998). Different from CLIMAP, the new
patterns reveal ice-free conditions in the eastern
Nordic Seas during LGM summer and a sea-ice
cover only reaching down to west ofIceland during winter. In the tropical divergence zone the
15
20
25
sea surface temperature eC)
Fig. 3. CLIMAP August sea surface temperatures (SSTs) for the Atlantic Ocean during the Last Glacial Maximum
(LGM). Modified according to CLIMAP (1984; http://ingrid.ldgo.columbia.edu).