Paleoceanographic data suggest rapid perturbations in the mode of ocean thermohaline circulation and temperature distribution, that have occurred during warm and cold climate stages all over the Quaternary. Sudden climate changes will also occur in the future as a function of both natural climate variability and anthropogenic influence. Ocean climate changes exert a strong influence on the atmosphere through the hydrological cycle, by shifts in regional and basin-scale patterns of intimately coupled ocean- atmosphere climate modes, e.g., the ENSO and NAO, the Atlantic and Indian Ocean dipoles, and through impacts on ocean-continent linkages via monsoons and trade wind systems, as well as by shifts in ITCZ and Westerlies. In turn, this change also has a significant impact on continental climates, causing changes in moisture balance, shifts in vegetation and weathering, and variations in glacier extent and river runoff.
Through an international workshop we aim for an improved level of cooperation between climate research teams focusing on climate modeling (meteorology, physical and chemical oceanography, atmosphere-ocean -vegetation coupling) and paleoclimatic reconstructions (paleoceanography, micropaleontology, isotope geo-chemistry).
This workshop will focus on:
- A merging of proxy records of past ocean circulation and atmospheric climates with historical data of the last 200 years;
- A comparison of historical and proxy records with climate regimes provided by Earth system modeling, including potential model extrapolations of the hydrological cycle from the Past into the Future;
- An assessment of the impact of ocean circulation changes at decadal to centennial time scales on continental climate conditions such as droughts, floods, vegetation changes, and weathering; and
- An improved approach for separating natural climate forcings from man-made factors of climate change.
During the workshop we plan:
1. To assess the role of oceanic SST patterns on ocean evaporation in tropical and mid latitudes for recent and past precipitation patterns, e.g., the ITCZ, African, Indian and Asian monsoons as well as snow fall in high latitudes, using instrumental records, proxy-based quantitative reconstructions, and model simulations. For the comparison with high resolution sea-surface temperature records from all ocean basins we particularly aim:
- To summarize past variations in continental precipitation/humidity, both in low and high latitudes by means of proxy-reconstructions such as low sea-surface salinity in marginal seas and river plumes, absolute dated speleothem records, pollen and biomarkers in marine and terrestrial sediments of the last 4 My.
- To search for additional proxies of past precipitation changes on land from marine records.
- To select important past time slices most indicative for the study of (globally and/or regionally) extreme scenarios in continental humidity and aridity.
- To compile measured spatial and temporal changes in ocean sea surface temperatures and evaporation (e.g., shipboard data) over the last 150 years and Holocene (e.g., in coop. with NDC Boulder and Norwich)
2. To assess feedbacks of ocean warming on the hydrological cycle and continental humidity, including hurricane activity, in particular,
- To search for the cutting edge in modeling the hydrological cycle at high spatial resolution at decadal to centennial time scales, comparable to proxy reconstructions.
- To assess potential future changes in the hydrological cycle for the next few hundreds of years
3. To focus on key requirements needed for an international perspective to advance the field.
Financial support
The workshop is financially supported by NSF, PAGES and IMAGES. Each participant (except for PhD students) will be asked for a partial contribution to the workshop expenses (to cover either hotel expenses or travel) from his/her own research funds.
˜ 35 scientists already expressed their strong interest to participate. Some funding for students' participation is still available.
Steering Committee
Gerald Ganssen, President of EGU, Amsterdam,gerald.ganssen@falw.vu.nl
Georg Hoffmann, Saclay / Paris,georg.hoffmann@cea.fr
Mark Maslin, UCL London,mmaslin@geography.ucl.ac.uk
Michael Sarnthein, Univ. of Kiel (chair),ms@gpi.uni-kiel.de
Ralph Schneider, Univ. of Kiel,schneider@gpi.uni-kiel.de
Lowell Stott, USC-LA, Ca,Stott@usc.edu
Robert Thunell, Univ. of South Carolina,thunell@geol.sc.edu