A coherent response of Southern Indian Ocean to the Antarctic climate: Implications to the lead, lags of atmospheric CO
- PDF / 1,122,696 Bytes
- 8 Pages / 595.276 x 790.866 pts Page_size
- 53 Downloads / 177 Views
Ó Indian Academy of Sciences (0123456789().,-volV)(0123456 789().,-volV)
A coherent response of Southern Indian Ocean to the Antarctic climate: Implications to the lead, lags of atmospheric CO2 during deglaciation A C NARAYANA1,*, P DIVAKAR NAIDU2, P G BHAVANI1 and MASOOD AHMAD3 1 Centre for Earth, Ocean and Atmospheric 2 CSIR-National Institute of Oceanography, 3
Sciences, University of Hyderabad, Hyderabad 500 046, India. Dona Paula, Goa 403 002, India. Formerly CSIR-National Geophysical Research Institute, Hyderabad 500 007, India. *Corresponding author. e-mail: [email protected] MS received 28 December 2019; revised 14 July 2020; accepted 21 July 2020
A record of d18Oc from the Indian sector of Southern Ocean and atmospheric CO2, and d18O of European Project for Ice Coring in Antarctica (EPICA) and Greenland Ice Sheet Project 2 (GISP2) reveals that a coherent response between d18O record of Antarctic ice core and the d18Oc record from Southern Indian Ocean during the deglaciation with initial warming starting around 18 kyr BP which is in agreement with the raise of atmospheric CO2 during same time. A distinct asynchrony between the records of d18Oc from the Southern Indian Ocean and d18O of GISP2 during the last deglaciation is noticed. We report that Southern Ocean degassing played an important role in raising atmospheric CO2 through Atlantic Meridional Overturning Circulation (AMOC), which has an implication in triggering abrupt climate events through coupling of ocean and atmospheric processes. Keywords. Southern Ocean; Antarctic climate; atmospheric CO2; d18O records; deglaciation.
1. Introduction The causes for Pleistocene ice ages are usually attributed to the astronomical forcing (Hays et al. 1976), which has been debated extensively. Antarctic ice cores have revealed low and high concentration of greenhouse gases during glacial and interglacial periods, respectively (Petit et al. 1999), which suggests that they too may be part of the cause. However, there is no general agreement among various records on the phase relationship between d18O of planktic foraminifera and CO2 from the northern and southern hemispheres, especially during the deglaciation (Shakun et al. 2012). Hence, the CO2 role in driving the glacial and interglacial cycles has not been understood clearly. For example, based on proxy data, it is
suggested that CO2 is the main driver of the ice ages (Luthi et al. 2008) on the one hand; on the other hand, interpretations such as (i) CO2 being a feedback from warming (Alley and Clark 1999), and (ii) CO2 is a consequence and may not be the cause of past climate change (Weaver et al. 1998), have also been made. More recently, the new concept has been added to address the triggering force of deglaciation that the CO2 initiates the rise in temperatures (Shakun et al. 2012). The period from 11 to 19 kyr include the climate transition from the last glacial to the Holocene. The documentation from ice cores of polar region and other climate archives suggest that the climate variation patterns d
Data Loading...
