Reversed flow of Atlantic deep water during the Last Glacial Maximum.
The meridional overturning circulation (MOC) of the Atlantic Ocean is considered to be one of the most important components of the climate system. This is because its warm surface currents, such as the Gulf Stream, redistribute huge amounts of energy from tropical to high latitudes and influence reg...
| Main Authors: | , , , , , , , |
|---|---|
| Format: | Journal article |
| Language: | English |
| Published: |
2010
|
| _version_ | 1797077157518770176 |
|---|---|
| author | Negre, C Zahn, R Thomas, A Masqué, P Henderson, G Martínez-Méndez, G Hall, I Mas, J |
| author_facet | Negre, C Zahn, R Thomas, A Masqué, P Henderson, G Martínez-Méndez, G Hall, I Mas, J |
| author_sort | Negre, C |
| collection | OXFORD |
| description | The meridional overturning circulation (MOC) of the Atlantic Ocean is considered to be one of the most important components of the climate system. This is because its warm surface currents, such as the Gulf Stream, redistribute huge amounts of energy from tropical to high latitudes and influence regional weather and climate patterns, whereas its lower limb ventilates the deep ocean and affects the storage of carbon in the abyss, away from the atmosphere. Despite its significance for future climate, the operation of the MOC under contrasting climates of the past remains controversial. Nutrient-based proxies and recent model simulations indicate that during the Last Glacial Maximum the convective activity in the North Atlantic Ocean was much weaker than at present. In contrast, rate-sensitive radiogenic (231)Pa/(230)Th isotope ratios from the North Atlantic have been interpreted to indicate only minor changes in MOC strength. Here we show that the basin-scale abyssal circulation of the Atlantic Ocean was probably reversed during the Last Glacial Maximum and was dominated by northward water flow from the Southern Ocean. These conclusions are based on new high-resolution data from the South Atlantic Ocean that establish the basin-scale north to south gradient in (231)Pa/(230)Th, and thus the direction of the deep ocean circulation. Our findings are consistent with nutrient-based proxies and argue that further analysis of (231)Pa/(230)Th outside the North Atlantic basin will enhance our understanding of past ocean circulation, provided that spatial gradients are carefully considered. This broader perspective suggests that the modern pattern of the Atlantic MOC-with a prominent southerly flow of deep waters originating in the North Atlantic-arose only during the Holocene epoch. |
| first_indexed | 2024-03-07T00:13:50Z |
| format | Journal article |
| id | oxford-uuid:7a29a9a5-3b58-4dc9-9593-03c6aa86f852 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T00:13:50Z |
| publishDate | 2010 |
| record_format | dspace |
| spelling | oxford-uuid:7a29a9a5-3b58-4dc9-9593-03c6aa86f8522022-03-26T20:42:07ZReversed flow of Atlantic deep water during the Last Glacial Maximum.Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:7a29a9a5-3b58-4dc9-9593-03c6aa86f852EnglishSymplectic Elements at Oxford2010Negre, CZahn, RThomas, AMasqué, PHenderson, GMartínez-Méndez, GHall, IMas, JThe meridional overturning circulation (MOC) of the Atlantic Ocean is considered to be one of the most important components of the climate system. This is because its warm surface currents, such as the Gulf Stream, redistribute huge amounts of energy from tropical to high latitudes and influence regional weather and climate patterns, whereas its lower limb ventilates the deep ocean and affects the storage of carbon in the abyss, away from the atmosphere. Despite its significance for future climate, the operation of the MOC under contrasting climates of the past remains controversial. Nutrient-based proxies and recent model simulations indicate that during the Last Glacial Maximum the convective activity in the North Atlantic Ocean was much weaker than at present. In contrast, rate-sensitive radiogenic (231)Pa/(230)Th isotope ratios from the North Atlantic have been interpreted to indicate only minor changes in MOC strength. Here we show that the basin-scale abyssal circulation of the Atlantic Ocean was probably reversed during the Last Glacial Maximum and was dominated by northward water flow from the Southern Ocean. These conclusions are based on new high-resolution data from the South Atlantic Ocean that establish the basin-scale north to south gradient in (231)Pa/(230)Th, and thus the direction of the deep ocean circulation. Our findings are consistent with nutrient-based proxies and argue that further analysis of (231)Pa/(230)Th outside the North Atlantic basin will enhance our understanding of past ocean circulation, provided that spatial gradients are carefully considered. This broader perspective suggests that the modern pattern of the Atlantic MOC-with a prominent southerly flow of deep waters originating in the North Atlantic-arose only during the Holocene epoch. |
| spellingShingle | Negre, C Zahn, R Thomas, A Masqué, P Henderson, G Martínez-Méndez, G Hall, I Mas, J Reversed flow of Atlantic deep water during the Last Glacial Maximum. |
| title | Reversed flow of Atlantic deep water during the Last Glacial Maximum. |
| title_full | Reversed flow of Atlantic deep water during the Last Glacial Maximum. |
| title_fullStr | Reversed flow of Atlantic deep water during the Last Glacial Maximum. |
| title_full_unstemmed | Reversed flow of Atlantic deep water during the Last Glacial Maximum. |
| title_short | Reversed flow of Atlantic deep water during the Last Glacial Maximum. |
| title_sort | reversed flow of atlantic deep water during the last glacial maximum |
| work_keys_str_mv | AT negrec reversedflowofatlanticdeepwaterduringthelastglacialmaximum AT zahnr reversedflowofatlanticdeepwaterduringthelastglacialmaximum AT thomasa reversedflowofatlanticdeepwaterduringthelastglacialmaximum AT masquep reversedflowofatlanticdeepwaterduringthelastglacialmaximum AT hendersong reversedflowofatlanticdeepwaterduringthelastglacialmaximum AT martinezmendezg reversedflowofatlanticdeepwaterduringthelastglacialmaximum AT halli reversedflowofatlanticdeepwaterduringthelastglacialmaximum AT masj reversedflowofatlanticdeepwaterduringthelastglacialmaximum |