Indian winter and summer monsoon strength over the 4.2 ka BP event in foraminifer isotope records from the Indus River delta in the Arabian Sea
<p>The plains of northwest South Asia receive rainfall during both the Indian summer (June–September) and winter (December–March) monsoon. Researchers have long attempted to deconstruct the influence of these precipitation regimes in paleoclimate records, in order to better understand regional...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2019-01-01
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| Series: | Climate of the Past |
| Online Access: | https://www.clim-past.net/15/73/2019/cp-15-73-2019.pdf |
| _version_ | 1818138014660952064 |
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| author | A. Giesche M. Staubwasser C. A. Petrie D. A. Hodell |
| author_facet | A. Giesche M. Staubwasser C. A. Petrie D. A. Hodell |
| author_sort | A. Giesche |
| collection | DOAJ |
| description | <p>The plains of northwest South Asia receive rainfall during both the Indian
summer (June–September) and winter (December–March) monsoon. Researchers
have long attempted to deconstruct the influence of these precipitation
regimes in paleoclimate records, in order to better understand regional
climatic drivers and their potential impact on human populations. The
mid–late Holocene transition between 5.3 and 3.3 ka is of particular
interest in this region because it spans the period of the Indus Civilization
from its early development, through its urbanization, and onto eventual
transformation into a rural society. An oxygen isotope record of the
surface-dwelling planktonic foraminifer <i>Globigerinoides ruber</i> from
the northeast Arabian Sea provided evidence for an abrupt decrease in
rainfall and reduction in Indus River discharge at 4.2 ka, which the authors
linked to the decline in the urban phase of the Indus Civilization
(Staubwasser et al., 2003). Given the importance of this study, we used the
same core (63KA) to measure the oxygen isotope profiles of two other
foraminifer species at decadal resolution over the interval from 5.4 to
3.0 ka and to replicate a larger size fraction of <i>G. ruber</i> than
measured previously. By selecting both thermocline-dwelling
(<i>Neogloboquadrina dutertrei</i>) and shallow-dwelling
(<i>Globigerinoides sacculifer</i>) species, we provide enhanced detail of
the climatic changes that occurred over this crucial time interval. We found
evidence for a period of increased surface water mixing, which we suggest was
related to a strengthened winter monsoon with a peak intensity over 200 years
from 4.5 to 4.3 ka. The time of greatest change occurred at 4.1 ka when
both the summer and winter monsoon weakened, resulting in a reduction in
rainfall in the Indus region. The earliest phase of the urban Mature Harappan
period coincided with the period of inferred stronger winter monsoon between
4.5 and 4.3 ka, whereas the end of the urbanized phase occurred some time
after the decrease in both the summer and winter monsoon strength by 4.1 ka.
Our findings provide evidence that the initial growth of large Indus urban
centers coincided with increased winter rainfall, whereas the contraction of
urbanism and change in subsistence strategies followed a reduction in
rainfall of both seasons.</p> |
| first_indexed | 2024-12-11T10:05:28Z |
| format | Article |
| id | doaj.art-d8a5ffe46a5f434d8a55b52cdc878485 |
| institution | Directory Open Access Journal |
| issn | 1814-9324 1814-9332 |
| language | English |
| last_indexed | 2024-12-11T10:05:28Z |
| publishDate | 2019-01-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Climate of the Past |
| spelling | doaj.art-d8a5ffe46a5f434d8a55b52cdc8784852022-12-22T01:11:57ZengCopernicus PublicationsClimate of the Past1814-93241814-93322019-01-0115739010.5194/cp-15-73-2019Indian winter and summer monsoon strength over the 4.2 ka BP event in foraminifer isotope records from the Indus River delta in the Arabian SeaA. Giesche0M. Staubwasser1C. A. Petrie2D. A. Hodell3Godwin Laboratory for Palaeoclimate Research, Department of Earth Sciences, University of Cambridge, Cambridge, CB2 3EQ, UKInstitute for Geology and Mineralogy, University of Cologne, Zülpicher Str. 49a, 50674 Cologne, GermanyDepartment of Archaeology, University of Cambridge, Cambridge, CB2 3DZ, UKGodwin Laboratory for Palaeoclimate Research, Department of Earth Sciences, University of Cambridge, Cambridge, CB2 3EQ, UK<p>The plains of northwest South Asia receive rainfall during both the Indian summer (June–September) and winter (December–March) monsoon. Researchers have long attempted to deconstruct the influence of these precipitation regimes in paleoclimate records, in order to better understand regional climatic drivers and their potential impact on human populations. The mid–late Holocene transition between 5.3 and 3.3 ka is of particular interest in this region because it spans the period of the Indus Civilization from its early development, through its urbanization, and onto eventual transformation into a rural society. An oxygen isotope record of the surface-dwelling planktonic foraminifer <i>Globigerinoides ruber</i> from the northeast Arabian Sea provided evidence for an abrupt decrease in rainfall and reduction in Indus River discharge at 4.2 ka, which the authors linked to the decline in the urban phase of the Indus Civilization (Staubwasser et al., 2003). Given the importance of this study, we used the same core (63KA) to measure the oxygen isotope profiles of two other foraminifer species at decadal resolution over the interval from 5.4 to 3.0 ka and to replicate a larger size fraction of <i>G. ruber</i> than measured previously. By selecting both thermocline-dwelling (<i>Neogloboquadrina dutertrei</i>) and shallow-dwelling (<i>Globigerinoides sacculifer</i>) species, we provide enhanced detail of the climatic changes that occurred over this crucial time interval. We found evidence for a period of increased surface water mixing, which we suggest was related to a strengthened winter monsoon with a peak intensity over 200 years from 4.5 to 4.3 ka. The time of greatest change occurred at 4.1 ka when both the summer and winter monsoon weakened, resulting in a reduction in rainfall in the Indus region. The earliest phase of the urban Mature Harappan period coincided with the period of inferred stronger winter monsoon between 4.5 and 4.3 ka, whereas the end of the urbanized phase occurred some time after the decrease in both the summer and winter monsoon strength by 4.1 ka. Our findings provide evidence that the initial growth of large Indus urban centers coincided with increased winter rainfall, whereas the contraction of urbanism and change in subsistence strategies followed a reduction in rainfall of both seasons.</p>https://www.clim-past.net/15/73/2019/cp-15-73-2019.pdf |
| spellingShingle | A. Giesche M. Staubwasser C. A. Petrie D. A. Hodell Indian winter and summer monsoon strength over the 4.2 ka BP event in foraminifer isotope records from the Indus River delta in the Arabian Sea Climate of the Past |
| title | Indian winter and summer monsoon strength over the 4.2 ka BP event in foraminifer isotope records from the Indus River delta in the Arabian Sea |
| title_full | Indian winter and summer monsoon strength over the 4.2 ka BP event in foraminifer isotope records from the Indus River delta in the Arabian Sea |
| title_fullStr | Indian winter and summer monsoon strength over the 4.2 ka BP event in foraminifer isotope records from the Indus River delta in the Arabian Sea |
| title_full_unstemmed | Indian winter and summer monsoon strength over the 4.2 ka BP event in foraminifer isotope records from the Indus River delta in the Arabian Sea |
| title_short | Indian winter and summer monsoon strength over the 4.2 ka BP event in foraminifer isotope records from the Indus River delta in the Arabian Sea |
| title_sort | indian winter and summer monsoon strength over the 4 2 thinsp ka thinsp bp event in foraminifer isotope records from the indus river delta in the arabian sea |
| url | https://www.clim-past.net/15/73/2019/cp-15-73-2019.pdf |
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