INVESTIGADORES
MILANA Juan Pablo
congresos y reuniones científicas
Título:
Global warming and South American climate: are we approaching a threshold?
Autor/es:
MILANA, J. P
Lugar:
Oslo
Reunión:
Congreso; International Geological Congress; 2008
Institución organizadora:
IUGS
Resumen:
A recent hypothesis showed that there is a strong dynamic connection between south-central Andean precipitations and circumantarctic sea surface temperature anomalies (SSTA) and sea ice concentration (SIC). It is worth to emphasize that the referred region of the Andes is among those that are undergoing the most impressive drying trend in the last century in Earth. The region seems also to be connected to an unique place in Earth that shows cooling throughout the last century, the Bellinghausen sea, while the entire planet shows significant warming. Detailed SIC measurements show that wihle the arctic SIC decreased about 11% during the last 20 years, the Antarctic SIC has been quite stable. It is hypothesized here that this southern stability on SIC that is forcing a climate imbalance between hemispheres is achieved due to the fact some places of the circumantarctic sea are being cooled more than others, fueled by an accelerated ice-mass wasting of the shelves which is probably a not sustainable process. This large-scale cooling occurring in front to large ice shelves as in the Ross Sea, due to the fact large amounts of ice can be delivered to the sea and act cooling surface waters and produce recognizable SSTAs. These anomalies are then transported around the Antarctic continent by the circumantarctic ocean current, and were already recognized as SSTA “waves”, although linked to another origin. If this hypothesis is correct, he recognized global warming that is clearly today centered at the northern hemisphere will progressively force a disequilibrium with the southern hemisphere. This large scale energy imbalance seems to be maintained by a high rate of ablation at the Antarctic areas and therefore, a main research concern should not be directed to global warming itself but to know, how much thermal imbalance can exist between both hemispheres, as this would clearly affect global climate significantly, even changing some global circulation patterns and thus affecting climate on large regions of the world in a way we have not seen. It seems that the natural reaction of the ice-sea system would to increase ice delivery to the sea due to increased warming until a point this supply could not alleviate the excessive warming. On that point, the central-southern Andean drying trend will probably be reverted as SIC will decrease counteracting the present day process that affects this region in the way of limiting precipitations. Perhaps, the last decade has seen the beginning of this process, due to a slight increase of Andean precipitations within a neutral ENSO scenario. From a point of view of these regions, starting a reversion of the SIC trend observed on the SSTA at some circumantarctic areas is desirable, but how this process will interact with other subtropical or equatorial processes should be a matter of public concern.