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Climate changes and solar cycles recorded at the Holocene Paraná Delta, and their impact on human population.

Milana JP, Kröhling D - Sci Rep (2015)

Bottom Line: The evolution of this 17,400 km(2) delta enclosed in Plata estuary, can be tracked by a series of 343 successive coastal-ridges showing a c.11 years period, in coincidence with sunspot cycle, also found in some North Hemisphere coastal-ridge successions.Results suggest that aside the solar forcing, both short and medium term climate changes controlled delta evolution.An important learning is that a slight cooling would turn the highly productive pampas, into that unproductive desert and, given the lack of artificial irrigation systems, changing present-day warmhouse into a cooling cycle might be economically catastrophic for the region.

View Article: PubMed Central - PubMed

Affiliation: CONICET - Universidad Nacional de San Juan, InGeo, (5401) San Juan, Argentina.

ABSTRACT
The Paraná delta, growing at a rate of c. 2 km(2) yr(-1) since 6,000 yrs, is one of the most complete records of the Late Holocene in southern South America. The evolution of this 17,400 km(2) delta enclosed in Plata estuary, can be tracked by a series of 343 successive coastal-ridges showing a c.11 years period, in coincidence with sunspot cycle, also found in some North Hemisphere coastal-ridge successions. The Paraná delta shifted from fluvial, to wave-dominated, and back to the present fluvial-dominated delta, in response to climate changes associated with wind activity correlating with South American glacial cycles. The wave-dominated windy period coincides with the activation of the Pampean Sand Sea, suggesting desert conditions prevailed on the Pampas between 5,300 and 1,700 yrs, in coincidence with scarce or absent pre-historic aborigine remains ("archeological silence"). Further warmer and less windy conditions allowed human repopulation. Results suggest that aside the solar forcing, both short and medium term climate changes controlled delta evolution. An important learning is that a slight cooling would turn the highly productive pampas, into that unproductive desert and, given the lack of artificial irrigation systems, changing present-day warmhouse into a cooling cycle might be economically catastrophic for the region.

No MeSH data available.


Related in: MedlinePlus

Estimated times of habitation of aborigine cultures in different regions around the Paraná Delta according to various authors202627.Approximate location of culture regions are shown in the inset map. The scene, near Pehaujó town portrays today productive croplands over large draas (6km wavelength), reactivated during the mid-Holocene. Pehuajó is at 35°49’S, 61°54’W at the core Buenos Aires, the wealthiest state of Argentina.
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f4: Estimated times of habitation of aborigine cultures in different regions around the Paraná Delta according to various authors202627.Approximate location of culture regions are shown in the inset map. The scene, near Pehaujó town portrays today productive croplands over large draas (6km wavelength), reactivated during the mid-Holocene. Pehuajó is at 35°49’S, 61°54’W at the core Buenos Aires, the wealthiest state of Argentina.

Mentions: Delta major structural changes indicate a period of increased wind energy lasting from c. 5,300 to 1,720 yrs BP. Due to this delta is enclosed within the Plata estuary and a northeastward sand-drift was needed to shape these ridges (Fig. 1), waves must be generated within the estuary by N to NE directed winds, perhaps like the “Pampero” windstorms. We believe that climate changes recorded here are not merely a local or regional phenomenon. There is significant evidence of a major reactivation of the Pampean Sand Sea during the mid-Holocene, and several authors extracted a regional sand wind-drift from today stabilized dunes related to N-NE directed winds, while this dry, windy period was centered around 3,500 years BP, with the last dunes active until about 2,000 years BP121314151617. While there is not a complete agreement on the exact timing of this dry, sand-sea active period18, the few available dates show strong coincidences with our windy delta period. Anybody can see today these dormant large dunes and draas below the rich cropland of the Pampas (Fig. 4), just like the Damocles sword.


Climate changes and solar cycles recorded at the Holocene Paraná Delta, and their impact on human population.

Milana JP, Kröhling D - Sci Rep (2015)

Estimated times of habitation of aborigine cultures in different regions around the Paraná Delta according to various authors202627.Approximate location of culture regions are shown in the inset map. The scene, near Pehaujó town portrays today productive croplands over large draas (6km wavelength), reactivated during the mid-Holocene. Pehuajó is at 35°49’S, 61°54’W at the core Buenos Aires, the wealthiest state of Argentina.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4526942&req=5

f4: Estimated times of habitation of aborigine cultures in different regions around the Paraná Delta according to various authors202627.Approximate location of culture regions are shown in the inset map. The scene, near Pehaujó town portrays today productive croplands over large draas (6km wavelength), reactivated during the mid-Holocene. Pehuajó is at 35°49’S, 61°54’W at the core Buenos Aires, the wealthiest state of Argentina.
Mentions: Delta major structural changes indicate a period of increased wind energy lasting from c. 5,300 to 1,720 yrs BP. Due to this delta is enclosed within the Plata estuary and a northeastward sand-drift was needed to shape these ridges (Fig. 1), waves must be generated within the estuary by N to NE directed winds, perhaps like the “Pampero” windstorms. We believe that climate changes recorded here are not merely a local or regional phenomenon. There is significant evidence of a major reactivation of the Pampean Sand Sea during the mid-Holocene, and several authors extracted a regional sand wind-drift from today stabilized dunes related to N-NE directed winds, while this dry, windy period was centered around 3,500 years BP, with the last dunes active until about 2,000 years BP121314151617. While there is not a complete agreement on the exact timing of this dry, sand-sea active period18, the few available dates show strong coincidences with our windy delta period. Anybody can see today these dormant large dunes and draas below the rich cropland of the Pampas (Fig. 4), just like the Damocles sword.

Bottom Line: The evolution of this 17,400 km(2) delta enclosed in Plata estuary, can be tracked by a series of 343 successive coastal-ridges showing a c.11 years period, in coincidence with sunspot cycle, also found in some North Hemisphere coastal-ridge successions.Results suggest that aside the solar forcing, both short and medium term climate changes controlled delta evolution.An important learning is that a slight cooling would turn the highly productive pampas, into that unproductive desert and, given the lack of artificial irrigation systems, changing present-day warmhouse into a cooling cycle might be economically catastrophic for the region.

View Article: PubMed Central - PubMed

Affiliation: CONICET - Universidad Nacional de San Juan, InGeo, (5401) San Juan, Argentina.

ABSTRACT
The Paraná delta, growing at a rate of c. 2 km(2) yr(-1) since 6,000 yrs, is one of the most complete records of the Late Holocene in southern South America. The evolution of this 17,400 km(2) delta enclosed in Plata estuary, can be tracked by a series of 343 successive coastal-ridges showing a c.11 years period, in coincidence with sunspot cycle, also found in some North Hemisphere coastal-ridge successions. The Paraná delta shifted from fluvial, to wave-dominated, and back to the present fluvial-dominated delta, in response to climate changes associated with wind activity correlating with South American glacial cycles. The wave-dominated windy period coincides with the activation of the Pampean Sand Sea, suggesting desert conditions prevailed on the Pampas between 5,300 and 1,700 yrs, in coincidence with scarce or absent pre-historic aborigine remains ("archeological silence"). Further warmer and less windy conditions allowed human repopulation. Results suggest that aside the solar forcing, both short and medium term climate changes controlled delta evolution. An important learning is that a slight cooling would turn the highly productive pampas, into that unproductive desert and, given the lack of artificial irrigation systems, changing present-day warmhouse into a cooling cycle might be economically catastrophic for the region.

No MeSH data available.


Related in: MedlinePlus