Holocene and deglacial ocean temperature variability in the Benguela upwelling region: Implications for low-latitude atmospheric circulation

نویسندگان

  • E. Christa Farmer
  • Peter B. deMenocal
  • Thomas M. Marchitto
چکیده

[1] Mg/Ca analyses of G. bulloides and abundances of N. pachyderma (left coiling) from Ocean Drilling Program (ODP) Leg 175 Hole 1084B in the Benguela coastal upwelling system document lower sea surface temperatures during the Last Glacial Maximum (LGM), Younger Dryas, mid-Holocene, and Little Ice Age in the southeastern Atlantic. Taking into consideration the possible effects of differential carbonate dissolution, the Mg/Ca data indicate Younger Dryas temperatures 2 –3 C cooler than those of the early Holocene and LGM temperatures 4 –5 C cooler than those of the early Holocene. The cool interval during the deglacial period at Hole 1084B matches the timing of Younger Dryas shifts in Cariaco Basin and Greenland Ice Sheet records and that of a nearby alkenone record. Comparison of mid-Holocene cooling at Hole ODP1084B with other highresolution records of Holocene and last deglacial sea surface temperatures from the tropical Atlantic implies consistent basin-wide changes in atmospheric circulation. A brief period of 1.5 –2 C cooling between 17.8 and 17.2 ka, if related to Heinrich event 1, is consistent with a previously hypothesized tropical origin of all Heinrich climate change events.

برای دانلود رایگان متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Opal burial in the equatorial Atlantic Ocean over the last 30 ka: Implications for glacial-interglacial changes in the ocean silicon cycle

[1] The Silicic Acid Leakage Hypothesis (SALH) suggests that, during glacial periods, excess silicic acid was transported from the Southern Ocean to lower latitudes, which favored diatom production over coccolithophorid production and caused a drawdown of atmospheric CO2. Downcore records of Th-normalized opal fluxes and Pa/Th ratios from seven equatorial Atlantic cores were used to reconstruct...

متن کامل

Asynchronous marine-terrestrial signals of the last deglacial warming in East Asia associated with low- and high-latitude climate changes.

A high-resolution multiproxy record, including pollen, foraminifera, and alkenone paleothermometry, obtained from a single core (DG9603) from the Okinawa Trough, East China Sea (ECS), provided unambiguous evidence for asynchronous climate change between the land and ocean over the past 40 ka. On land, the deglacial stage was characterized by rapid warming, as reflected by paleovegetation, and i...

متن کامل

Carbon isotope records reveal precise timing of enhanced Southern Ocean upwelling during the last deglaciation.

The Southern Ocean plays a prominent role in the Earth's climate and carbon cycle. Changes in the Southern Ocean circulation may have regulated the release of CO₂ to the atmosphere from a deep-ocean reservoir during the last deglaciation. However, the path and exact timing of this deglacial CO₂ release are still under debate. Here we present measurements of deglacial surface reservoir ¹⁴C age c...

متن کامل

Impact of abrupt deglacial climate change on tropical Atlantic subsurface temperatures.

Both instrumental data analyses and coupled ocean-atmosphere models indicate that Atlantic meridional overturning circulation (AMOC) variability is tightly linked to abrupt tropical North Atlantic (TNA) climate change through both atmospheric and oceanic processes. Although a slowdown of AMOC results in an atmospheric-induced surface cooling in the entire TNA, the subsurface experiences an even...

متن کامل

Northern High-Latitude Climate Changes During the Holocene as Simulated by Circulation Models

To simulate the evolution of Holocene climate, forcing factors for the northern high-latitude climate are examined using different numerical models. A global coupled atmosphere–ocean circulation model driven by astronomical forcing over the last 7,000 years shows a long-term sea-surface temperature decrease in the Nordic Seas region associated with changes in seasonal insolation. A continuous c...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 2005