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)

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.     

Reply to comment by J. Trampert

Books Reviewed in this Article:
Seismic tomography and mantle circulation Eds O'Nions, R. K. & Parsons, B., Royal Society of London Special Publication , 1989, ISBN 0854 033823.     

Exhumed hydrocarbon traps in East Greenland: A comment on Andrews et al. (2020)

In a recent study, Andrews et al. (2020) describe “exhumed hydrocarbon traps” in North-East Greenland. The basic premise for their interpretation is that dark-coloured, pyrobitumen-bearing sandstones represent the remnants of once buried petroleum reservoirs. We do not see the necessary field or analytical evidence to support a model that has strong implications for resource evaluations. Andrews et al. (2020) have not considered previous published information on diagenetic and thermal maturity history of the area. A more probable model would include the intrusion of dykes and sills into a sedimentary succession with immature petroleum source rocks and reservoir-quality sandstones. The heating caused rapid generation of petroleum components and local hydrothermal circulation systems in adjacent porous sandstones. Any petroleum was rapidly destroyed leaving essentially only black grain-coatings and minor particles of pyrobitumen—essentially in one short-lived continuous process. The existence of new plays in the North Atlantic as proposed by Andrews et al. (2020) is in our opinion not substantiated as this requires analytical data from unaltered oils from the less mature parts of the sedimentary succession and considerations of thermal maturity and basin evolution. To draw conclusions that have a serious impact on resource evaluations based on the dark colouration of sandstones without comprehensive analytical data is, in our opinion, ill advised.