Hydrography of the subpolar North Atlantic during the Last Interglacial

Lead Research Organisation: University of East Anglia
Department Name: Environmental Sciences

Abstract

We intend to reconstruct detailed information on the past variability of climate from the subpolar region of the North Atlantic in order to obtain a better understanding of the factors controlling oceanic circulation and the modes of variability that have existed in the recent past. We plan to recover quantitative palaeoclimatic information about sea surface temperatures, the geographical distribution of drift ice and current patterns as well as information about the temperature and ventilation of the deep ocean. The main time period of interest is the last interglacial period, a warm phase some 125,000 years ago when climate was comparable to the present day but global average temperatures and sea levels were slightly elevated with respect to modern values. Our overall aim is to produce new palaeoclimatic data at four key North Atlantic localities which will characterize the temporal and spatial evolution of the surface and deep ocean circulation from the end of the extremely cold conditions of the penultimate glacial period, through full interglacial conditions, to the inception of glaciation and the re-expansion of terrestrial ice sheets. This corresponds to the time interval between 135,000 and 100,000 years ago. This investigation intends to address deficiencies in our knowledge by focusing on high resolution analyses of palaeoceanographic and palaeoclimatic parameters using deep-sea sediment core material collected from high accumulation rate sites that offers the possibility of reconstructing North Atlantic surface and deep hydrography on centennial timescales. The climatic information we recover will inform us, not only about the way climate has varied in the past and the relative influence of the various climatic mechanisms, but also give us important clues about possible future changes.
 
Description The climatic conditions of the last interglacial period (125,000 years ago) are the subject of much interest as the higher sea levels and smaller polar ice sheets may be analogues for future changes in climate. The principal focus of the project is to reconstruct the past variations in the strength of the subpolar gyre, which is an essential component of the mid- to high- latitude North Atlantic circulation, that until now has not been studied in detail.
In this work we show that the mean state of the subpolar gyre circulation was significantly different from the present configuration. Our finding of greater warmth in the surface ocean allied to higher sea levels is in keeping with modelling experiments. Our principal finding is that a circulation pattern similar to the negative phase of the North Atlantic Oscillation was the norm during the warm phase of the last interglacial and that this would have inhibited deep convection in the Labrador Sea.
This research provides the clearest evidence to date that the subpolar North Atlantic surface circulation can operate in quite different modes during interglacial times. Future climate warming is expected to continue to freshen the North Atlantic and hence our results are relevant to any consideration of the sensitivity and potential stability/instability of the climate system in the future.
Exploitation Route These findings can be used to ground truth different climate models and provide new insight into the sensitivity and potential stability/instability of the climate system in the future.
Sectors Education,Environment,Other

 
Description In this work we show that the mean state of the subpolar gyre circulation was significantly different from the present configuration. Our finding of greater warmth in the surface ocean provides the clearest evidence to date that the subpolar North Atlantic surface circulation can operate in quite different modes during interglacial times. Future climate warming is expected to continue to freshen the North Atlantic and hence our results are relevant to any consideration of the sensitivity and potential stability/instability of the climate system in the future.
First Year Of Impact 2014
Sector Environment,Other
Impact Types Societal,Economic

 
Description QRA conference
Amount £500 (GBP)
Organisation Quaternary Research Association 
Sector Academic/University
Country United Kingdom
Start 01/2014 
End 12/2014
 
Description Arranged and convened a one-day meeting at the Geological Society, Burlington House, London (15/5/14) - Chronology and Climate of the Last Interglacial 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Type Of Presentation keynote/invited speaker
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact The last interglacial period is of great interest as it appears to have experienced elevated temperatures and sea levels relative to the Holocene and had ocean circulation patterns that were significantly different from the present. This one-day workshop aimed to bring together a broad community of researchers interested in the climate, timing and duration of the last interglacial period. The main aim was to engage with diverse professional groups within the Geological Society, Natural England, and the British Geological Survey.
Speakers were invited from the UK, USA, and Norway and we had ~80 participants attending from the UK and around Europe.
An open discussion with all speakers marked the end of the event.

Discussions of uncertainties identified mixed messages provided to the public/in scientific literature and the problem that this poses for synthesising available data.
Year(s) Of Engagement Activity 2014
URL https://www.uea.ac.uk/environmental-sciences/news-and-events/conferences/chronology-and-climate