کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
6429748 1634768 2014 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Ocean-atmosphere climate shift during the mid-to-late Holocene transition
ترجمه فارسی عنوان
تغییر آب و هوای اقیانوس آرام در طی گذر از نیمه هولزن
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات علوم زمین و سیاره ای (عمومی)
چکیده انگلیسی


- The mid-to-late Holocene transition: Dynamic response to gradual insolation forcing.
- Central Water circulation amplifies climate sensitivity to small insolation forcing.
- Focus on modern NAO-AMO circulation modes, oversimplifies past climate dynamics.
- 1930s regime shift: A possible analogue for climate dynamics during the HTM.

Climate records of the mid-to-late Holocene transition, between 3-4 thousand years before present (ka), often exhibit a rapid change in response to the gradual change in orbital insolation. Here we investigate North Atlantic Central Water circulation as a possible mechanism regulating the latitudinal temperature gradient (LTG), which, in turn, amplifies climate sensitivity to small changes in solar irradiance. Through this mechanism, sharp climate events and transitions are the result of a positive feedback process that propagates and amplifies climate events in the North Atlantic region. We explore these linkages using an intermediate water temperature record reconstructed from Mg/Ca measurements of benthic foraminifera (Hyalinea balthica) from a sediment core off NW Africa (889 m depth) between 0 to 5.5 ka. Our results show that Eastern North Atlantic Central Waters (ENACW) cooled by ∼1°±0.7 °C and densities decreased by σθ=0.4±0.2 between 3.3 and 2.6 ka. This shift in ENACW hydrography illustrates a transition towards enhanced mid-latitude atmospheric circulation after 2.7 ka in particular during cold events of the late-Holocene. The presented records demonstrate the important role of ENACW circulation in propagating the climate signatures of the LTG by reducing the meridional heat transfer from high to low latitudes during the transition from the Holocene Thermal Maximum to the late-Holocene. In addition, the dynamic response of ENACW circulation to the gradual climate forcing of LTGs provides a prime example of an amplifying climate feedback mechanism.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Earth and Planetary Science Letters - Volume 388, 15 February 2014, Pages 18-26
نویسندگان
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