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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

General Map of the Paraná Delta showing major delta growth stages and the continuous coastal ridges succession preserved.Boxes labeled 2A–D ar shown in detail in Fig. 2; small boxes labeled 3A-D give location of images of Fig. 3. The upper right corner box shows the real part of the continuous Morlet wavelet spectra of the Paraná river (courtesy of A. Pasquini21), with dark grays corresponding to high values of the transform coefficients (power), showing a strong decadal periodicity. Map elaborated by the authors using CONAE imagery and graphical software CorelDraw 12.0 TM.
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f1: General Map of the Paraná Delta showing major delta growth stages and the continuous coastal ridges succession preserved.Boxes labeled 2A–D ar shown in detail in Fig. 2; small boxes labeled 3A-D give location of images of Fig. 3. The upper right corner box shows the real part of the continuous Morlet wavelet spectra of the Paraná river (courtesy of A. Pasquini21), with dark grays corresponding to high values of the transform coefficients (power), showing a strong decadal periodicity. Map elaborated by the authors using CONAE imagery and graphical software CorelDraw 12.0 TM.

Mentions: Deltas are excellent environmental archives, as they are the main sink of river sediments. The Paraná-Plata drainage basin (Fig. 1) is the second largest in South America and the third worldwide, while average discharge rates sixth in the world. About 160 million tons of sediment are delivered annually by the Paraná to the Plata estuary, creating a subaerial delta plain that only in the previous 106 years grew 196 km2 [Ref. 1] creating land at a rate of 2.49 km2/yr [Ref. 2]. This delta is especially suitable as an archive of the evolution of a large area as it is protected from marine erosion by the Plata estuary which also restricts the delta-lobe shifting process. In spite of this protection, large environmental changes of continental scale3 reshaped the entire delta, as we will demonstrate. The importance of this geoarchive is crucial to understand prehistorical populations, but as it is located within the most industrialized and developed region of South America, is fundamental to build environmental models of the region to forecast possible crisis related to climate changes.


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

Milana JP, Kröhling D - Sci Rep (2015)

General Map of the Paraná Delta showing major delta growth stages and the continuous coastal ridges succession preserved.Boxes labeled 2A–D ar shown in detail in Fig. 2; small boxes labeled 3A-D give location of images of Fig. 3. The upper right corner box shows the real part of the continuous Morlet wavelet spectra of the Paraná river (courtesy of A. Pasquini21), with dark grays corresponding to high values of the transform coefficients (power), showing a strong decadal periodicity. Map elaborated by the authors using CONAE imagery and graphical software CorelDraw 12.0 TM.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f1: General Map of the Paraná Delta showing major delta growth stages and the continuous coastal ridges succession preserved.Boxes labeled 2A–D ar shown in detail in Fig. 2; small boxes labeled 3A-D give location of images of Fig. 3. The upper right corner box shows the real part of the continuous Morlet wavelet spectra of the Paraná river (courtesy of A. Pasquini21), with dark grays corresponding to high values of the transform coefficients (power), showing a strong decadal periodicity. Map elaborated by the authors using CONAE imagery and graphical software CorelDraw 12.0 TM.
Mentions: Deltas are excellent environmental archives, as they are the main sink of river sediments. The Paraná-Plata drainage basin (Fig. 1) is the second largest in South America and the third worldwide, while average discharge rates sixth in the world. About 160 million tons of sediment are delivered annually by the Paraná to the Plata estuary, creating a subaerial delta plain that only in the previous 106 years grew 196 km2 [Ref. 1] creating land at a rate of 2.49 km2/yr [Ref. 2]. This delta is especially suitable as an archive of the evolution of a large area as it is protected from marine erosion by the Plata estuary which also restricts the delta-lobe shifting process. In spite of this protection, large environmental changes of continental scale3 reshaped the entire delta, as we will demonstrate. The importance of this geoarchive is crucial to understand prehistorical populations, but as it is located within the most industrialized and developed region of South America, is fundamental to build environmental models of the region to forecast possible crisis related to climate changes.

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