Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2019 Jan 2;116(1):67-72.
doi: 10.1073/pnas.1808103115. Epub 2018 Dec 24.

Precise timing of abrupt increase in dust activity in the Middle East coincident with 4.2 ka social change

Stacy A Carolin  1 , Richard T Walker  2 , Christopher C Day  2 , Vasile Ersek  3 , R Alastair Sloan  4 , Michael W Dee  5 , Morteza Talebian  6 , Gideon M Henderson  2
Affiliations

Precise timing of abrupt increase in dust activity in the Middle East coincident with 4.2 ka social change

Stacy A Carolin et al. Proc Natl Acad Sci U S A. .

Abstract

The extent to which climate change causes significant societal disruption remains controversial. An important example is the decline of the Akkadian Empire in northern Mesopotamia ∼4.2 ka, for which the existence of a coincident climate event is still uncertain. Here we present an Iranian stalagmite record spanning 5.2 ka to 3.7 ka, dated with 25 U/Th ages that provide an average age uncertainty of 31 y (1σ). We find two periods of increased Mg/Ca, beginning abruptly at 4.51 and 4.26 ka, and lasting 110 and 290 y, respectively. Each of these periods coincides with slower vertical stalagmite growth and a gradual increase in stable oxygen isotope ratios. The periods of high Mg/Ca are explained by periods of increased dust flux sourced from the Mesopotamia region, and the abrupt onset of this dustiness indicates threshold behavior in response to aridity. This interpretation is consistent with existing marine and terrestrial records from the broad region, which also suggest that the later, longer event beginning at 4.26 ka is of greater regional extent and/or amplitude. The chronological precision and high resolution of our record indicates that there is no significant difference, at decadal level, between the start date of the second, larger dust event and the timing of North Mesopotamia settlement abandonment, and furthermore reveals striking similarity between the total duration of the second dust event and settlement abandonment. The Iranian record demonstrates this region's threshold behavior in dust production, and its ability to maintain this climate state for multiple centuries naturally.

Keywords: 4.2 ka event; Mesopotamia; drought; dust; stalagmite.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Fig. 1.
Fig. 1.
Correlation maps of archeological site Tell Leilan (black “+”) rainfall with European Centre for Medium-range Weather Forecasts Re-Analysis Interim (ERA-Interim) model forecast total precipitation (resolution ∼80 km) (41). White areas indicate areas where P > 0.10. The ERA-Interim model forecast record at (37°N, 41.5°E) was used to represent Tell Leilan rainfall. (A) Correlation map using annual precipitation records, constructed by calculating the 12-mo average of each year centered on winter, i.e., July 1979 to June 1980, July 1980 to June 1981, etc. (B) Upper uses only winter months October through March, and Lower uses only spring and summer months March through August, to create yearly records highlighting a particular season. A also shows the direction and relative speed in arrow size of 850-mb-level winds from July 5, 2009, 12:00 GMT (41), an example time period of a severe dust event in Tehran, Iran, in which dust was sourced from the Mesopotamia region (25, 28). The locations of paleoclimate records discussed in the text are marked with circles; labels are provided in A. Source area of 92% of contributions of PM10 (fine dust with particles smaller than 10 μm) in Tehran (50 km from location 9; this study) during 2009–2010 dusty episodes are shown by dotted boxed area in A (28).
Fig. 2.
Fig. 2.
Mid-to-late Holocene records of climatology in the Mesopotamia region. (A) Marine records: 1, Red Sea sediment core GeoB 5836-2 shallow dwelling foraminifera Globigerinoides ruber δ18O (5); 2, Gulf of Oman Core M5-422 eolian dolomite concentration (percent weight) (3). Terrestrial records: 3, Buca della Ranella RL4 stalagmite δ18O record (6, 19); 4, Sofular cave So-1 stalagmite δ18O record (42); 5, Jeita J-1 stalagmite δ18O record (43); 6, Soreq cave multiple stalactite and stalagmite δ18O records (8, 44); 7, Qunf cave Q5 stalagmite δ18O record (45); 8, Tonnel’naya cave TON-2 stalagmite δ18O record (46). Locations of the caves are shown in Fig. 1. (B) Local climate proxies, Mg/Ca (millimoles per mole) and δ13C (per mil), measured in the Buca della Ranella RL4 stalagmite (6, 19), are plotted with our high-resolution δ18O (per mil) record (19), all on the updated age model (19). A gray dotted line in both A and B indicates the location of date 4.2 ka before 1950 CE.
Fig. 3.
Fig. 3.
GZ14-1 age v. depth plot with OxCal Poisson process deposition age model 68% (black) and 95% (dark gray) confidence ranges (30, 31). Original individual U-series samples’ ages are plotted as black “x” shapes. Individual samples’ modeled age distributions are shown in dark gray (68%) and light gray (95%). (Inset) GZ14-1’s mean extension rate (micrometers per year), plotted as a 20-y moving average of the annually interpolated OxCal mean extension rate, is included as a subset.
Fig. 4.
Fig. 4.
Timing of environmental changes in Middle East region compared with archeological settlement records. (A) Proxy records of Mesopotamia-sourced dust event activity: i, GZ14-1 Mg/Ca (millimoles per mole) (this study); ii, Gulf of Oman Core M5-422 eolian dolomite concentration (percent weight) (3), plotted on an updated age model (SI Appendix). Time resolution of GZ14-1 is an average of ∼2 y during fast growth and an average of ∼10 y to 15 y during slow growth, with slow growth period found within intervals highlighted in gray (growth rate shown in Fig. 3). In both records, greater Mg/Ca or dolomite % wt indicates more dolomite-containing eolian dust deposits. (B) Proxy records of aridity climate: i, GZ14-1 δ18O (this study), with more positive values interpreted as drier conditions to an unknown magnitude on interannual timescales; ii, Jeita cave stalagmite δ18O record as in Fig. 2A, with more enriched δ18O interpreted as drier conditions (43); iii, Soreq cave multiple stalactite and stalagmite sample δ13C records, with more enriched δ13C interpreted as drier conditions (8, 44); iv, Red Sea sediment core GeoB 5836-2 G. ruber δ18O, as in Fig. 2A, with more enriched δ18O interpreted as greater evaporation and thus drier climate (5). (C) Graphical representation of the evolution of rain-fed agricultural settlements in north Mesopotamia, which became urbanized around 4.5 ka, were imperialized by Akkad around 4.26 ka, and then were suddenly abandoned at 4.19 ± 0.018 (1σ) ka (17), coincident with the decline of the Akkadian empire. Settlements returned at 3.90 ± 0.026 (1σ) ka (17). Modeled U/Th mean ages (blue circles) and 95% confidence ranges are plotted above each record. For the two GZ14-1 records, A, i and B, i, the ages are plotted only above A, i. The two vertical gray bars across all panels begin when Mg/Ca ratio in the GZ14-1 record rises greater than 3σ from the average ratio of the record for >10 y, and end when Mg/Ca returns to background levels (see Event Timing and Errors).
See this image and copyright information in PMC

Comment in

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Höflmayer F. The late third millennium B.C. In the ancient near east and eastern mediterranean: A time of collapse and transformation. In: Höflmayer F, editor. The Late Third Millennium in the Ancient Near East: Chronology, C14, and Climate Change. Univ Chicago; Chicago: 2017.
    1. Gasse F, Van Campo E. Abrupt post-glacial climate events in West Asia and North Africa monsoon domains. Earth Planet Sci Lett. 1994;126:435–456.
    1. Cullen HM, et al. Climate change and the collapse of the Akkadian empire: Evidence from the deep sea. Geology. 2000;28:379–382.
    1. Thompson LG, et al. Kilimanjaro ice core records: Evidence of Holocene climate change in tropical Africa. Science. 2002;298:589–593. - PubMed
    1. Arz HW, Lamy F, Pätzold J. A pronounced dry event recorded around 4.2 ka in brine sediments from the Northern Red Sea. Quat Res. 2006;66:432–441.

Publication types