Was there ice along the shore of the Sea of Galilee during the last 12,000?—Reply to a comment by Prange et al. (2007) and a comment by Friedman (2007) |
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| Authors: | Doron Nof Ian McKeague Nathan Paldor |
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| Institution: | (1) Department of Oceanography, Florida State University, Tallahassee, FL 32303, USA;(2) Geophysical Fluid Dynamics Institute, Florida State University, Tallahassee, FL 32303, USA;(3) Department of Biostatistics, Columbia University, New York, NY, USA;(4) Department of Atmospheric Science, The Hebrew University of Jerusalem, Jerusalem, Israel |
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| Abstract: | Prange et al. (2007) question our reconstruction of the Sea of Galilee (Lake Kinneret) paleoclimate and argue that a “careful” analysis of the
paleoclimatic analysis leads to much smaller cooling events than we have considered. By and large, their “careful” analysis
is based on correlating the paleotemperatures of the Lake with those of the northern Red-Sea that (geographically) is much
closer to the Lake than the two Mediterranean cores that we used. Ironically, their argument contradicts Friedman’s (2007) statements (the second comment on our original paper), which are based on still-closer cores and support our larger cooling choices. This issue alone would be enough to dismiss the uniqueness of PAL argument but there is another
issue with their work that we wish to comment on. In support of their own small cooling argument, PAL present winter correlation
maps that indeed show a stronger correlation of the northern Red-Sea SST to the lake SST than the correlation of Mediterranean
SST with the lake SST. This seemingly correct correlation argument of PAL is totally false (for both daily and millennial
time scales) because it has no climatological basis. On the daily time scale, all the storms that reach the Lake originate
in the Mediterranean Sea (to the west of the lake), not the Red-Sea (which lies 700 km south of the lake). Also, although
the lake and the Red-Sea are only 700 kilometers apart, their climates are very different because they are subject to two
totally different air masses. While the climate of the Red-Sea region is desert-like, the climate of the region surrounding
the lake is a typical wet Mediterranean climate. Seasonal correlation maps (and even monthly maps) such as those presented
by the authors filter out the storms that control the winter climate in the lake region because these storms occur on a daily scale. With this filtering, all
that one is left with is the low frequency first baroclinic mode, which merely reflects the Rossby radius scale (measured
from the lake). On the millennial time scale, cold events in the lake regions (from an earlier period) have been attributed
to Bond cycles and Heinrich events both of which are global and not local processes. As such, they are probably forced by
variability in the solar radiation rather than a local process implied by PAL. Overall, all that the PAL correlation shows
for both daily and millennial time scales is that changes in the temperature in the Red-Sea occur at the same time as they do in the Lake. But this does not say anything about the dynamics in question and does not imply that it is better
to use records from the Red-Sea (which does not lie within the path of the zonal winds reaching the Lake). Neglecting this
issue (as proposed by PAL) distorts the physics and reminds us of the classical statistical example for the limitations involved
in the interpretation of correlation—the incidence of lung cancer is strongly correlated with the incidence of carrying matches
in ones pocket even though the matches do not cause the cancer and the cancer does not force one to carry matches. |
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| Keywords: | Salt springs Plumes Lake freezing Convection Paleoclimate |
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